WO1999067798A2

WO1999067798A2 - Method and apparatus for switching electrical power at high voltages, high currents and high temperatures with rapid turn-on and turn-off at high repetition rates

Info

Publication number: WO1999067798A2
Application number: PCT/US1999/008548
Authority: WO
Inventors: Rahul R. Prasad; Mahadevan Krishnan; Niansheng Qi; Steven W. Gensler; John A. Edighoffer
Original assignee: Alameda Applied Sciences Corporation
Priority date: 1998-06-05
Filing date: 1999-04-19
Publication date: 1999-12-29
Also published as: WO1999067798A3

Abstract

Methods and apparatus for high voltage, high current, fast acting, high temperature, high repetition rate synthetic diamond electrical switch and an improved particle and radiation detector are disclosed. Energy absorbed from incident electrons, ultraviolet photons or other radiation sources including soft and hard x-rays, gamma rays, alpha particles, other types of ions, neutrons or other sub-atomic particles is used to decrease the resistance of a synthetic (CVD) diamond membrane from its normal, high resistance 'off' state to a temporary, low resistance 'on' state. The controlled variation of the resistance of the diamond allows the membrane, when connected to an external circuit, to act as a repetitively pulsed electrical switch. Without the particle or radiation energy input, the membrane exhibits its normal very high resistance (for example, greater than 1012 Φ) and is in the 'off' state with negligible current. With particle or radiation energy input, the resistance plunges to low values (for example, much less than 1 Φ) and the current increases. The superior electrical field strength and thermal conductivity of both natural and synthetic diamond relative to doped silicon semi-conductors allow diamond membranes to hold off higher voltage and operate at higher temperatures than silicon semi-conductor junctions of comparable size. Practical limits to silicon or silicon carbide semi-conductor switches are less than 6 kV voltage hold-off in a single switch that can switch current densities of about 100 A/cm2 with approximately 1 νs turn-on and turn-off times. Silicon switches are unidirectional and limited to less than 400 °K operation (with respect to operating temperature).

Description

METHOD AND APPARATUS FOR SWITCHING ELECTRICAL POWER AT

HIGH VOLTAGES, HIGH CURRENTS AND HIGH TEMPERATURES WITH

RAPID TURN-ON AND TURN-OFF AT HIGH REPETITION RATES

John A. Edighoffer, Pleasanton, CA

RELATED APPLICATIONS

This is a non-provisional utility application based upon provisional application Serial No. 60/088,166 filed on June 5, 1998, the priority for which is herein claimed under 35 U.S.C. § 119(e), the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention generally relates to methods and apparatus for providing solid-state, synthetic diamond switches and improved particle or radiation detectors. In particular, the present invention relates to bi-directional diamond switches capable of higher voltage operation at higher current densities and higher temperatures, with faster turn-on and turn-off than any existing silicon semi-conductor switch, and which allows repetitively pulsed operation at repetition rates that are as high as 10 GHz. Additionally, the present invention relates to methods and apparatus for measuring the flux or dose delivered to the diamond by an external trigger source (particles or radiation).

2. DESCRIPTIONOFTHERELATEDART

Pressurized spark gap switches, ignitrons and thyratrons have been used for many pulsed power capacitor discharge applications because no other switching devices have been developed that can both hold off the 10's of kilovolt charging levels and conduct 10' s of kilo-amperes of current when switched.

One drawback of spark gap switches that are used in pulsed power applications is the switch jitter and variability of the switch inductance. This is caused by an arc which forms between the two electrodes to force the switch into the conduction mode, i.e., when the switch closes. This arc causes the metal of the electrodes to ablate which results in limited life. The long period of time for the arc recovery in the spark gap switch is the primary reason for their limited repetition rate capability.

The irreproducibility in the number of arc "streamers" formed causes the switch to have an inductance that changes from shot to shot. This is of particular concern in fast rise time, high current pulsed power applications since they add the current pulses from several capacitor banks in parallel. The series inductance of the switch is relatively high because of the localized nature of the switch arc and the modest voltage hold off capability of the switch gas, both of which prevent the current return path from being placed very near the switch arc. For this reason, these switches are bulky. Moreover, switch jitter causes an asynchronous addition of the current pulses, elongating the rise time of the combined current pulse.

Semiconductor based solid state switches have limited operability in high voltage applications because of .the low electrical breakdown strength of most semiconductor materials. Low thermal conductivity limits the current handling capabilities of these switches. Fast recovery times, however, allow the switches to operate at very high repetition rate.

Switches used in the ground penetrating radar application must have opening and closing times of less than 10 ns to allow the generation of broadband pulses with central frequencies of approximately 100 MHz, and pulse repetition rates of approximately 1 kHz.

Conduction currents of approximately 1 kA at blocking voltages of around 100 kV are required. The switch must survive several million pulses. The state-of-the-art in semiconductor switches are optically triggered GaAs switches which meet some of these criteria but fall orders of magnitude short on several others including lifetime requirements. Further detail on optically triggered GaAs switches can be found in, for example, F.J. Zutavern et al, High Power Optically Activated Solid-State Switches, p.245, Artech House, Boston (1994).

Two practical examples of devices whose present gas and/or solid-state switches may be improved by replacement with the diamond switch in accordance with the present invention are excimer lasers and inverters for rail motors. Excimer lasers produce ultraviolet laser radiation using a discharge in an excimer gas medium, as further discussed in U.K. Sengupta, Krypton Fluoride Excimer Laser for Advanced Microlithography, Opt. Engg. 32 (10), 2410 (1993). Generally, a power supply is used to generate the discharge in the gas. This power supply typically includes a dc power supply that charges a capacitor bank that is discharged using a switch and one or more pulse compression and voltage amplification stages into the gas load. In order to produce UV radiation, the energy from the power supply must be deposited in the gas in a short duration - typically at around 50 ns. Since the conversion efficiency from electrical power to UV radiation is only about 1 %, even a medium powered laser emitting 100 mJ/pulse requires the power supply to deliver 10 J into the excimer gas. This leads to high peak currents that must be switched extremely rapidly. Because available switches (thyratrons and SCRs) are relatively slow, secondary pulse compression is necessary to further compress the power pulse. Low power excimer lasers such as those used for sub-micron lithography use SCRs and several magnetic pulse compression/voltage amplification stages as further discussed in, for example, W. Partlo et al., A Low Cost of Ownership KrF Excimer Laser Using a Novel Pulse Power and Chamber Configuration, SPIE Vol. 2440, 90 (1995). Because of the low power, SCRs used in these lasers can operate at repetition rates of approximately 1000 Hz. However, the use of SCRs limits the voltage switched to around 1 kV necessitating several magnetic pulse compression stages. This in turn leads to complexity and the potential for component failure.

Higher power excimer lasers used in industrial applications use thyratrons because of the higher voltage requirement. This reduces the complexity of the circuit since thyratrons can handle switching at up to 20 kV. However, a capacitive pulse compression circuit must still be employed to sharpen the pulse rise time to the required level. Because they are gas switches, thyratrons are limited to low repetition rates of approximately 100 Hz making the duty factors low. This is a disadvantage for several applications. In particular, switches used in excimer laser power supplies must also withstand high reverse voltages due to a large amount of reflected energy from the gas discharge. In order to use solid-state switches such as SCRs with very low reverse voltage hold-off, elaborate snubber circuits are necessary to limit the reverse voltage at the switch. This adds to the complexity of these circuits and increases the potential for component failure.

The slow turn-on and turn-off of existing solid state switches and thyratrons result in large heat dissipation in the switch, since most of the dissipation occurs during the rising and falling portions of the current when the on-state voltage is still high. This heat must be dissipated, limiting the repetition rate of the power supplies.

Most railway engines either directly use electrical power to run motors that power the wheels or convert diesel or other fuel power into electrical power to run motors. Rather than use a fixed line frequency of 50-60 Hz for these motors it is desirable to use variable frequencies to optimize the operational efficiency of such motors. The variable frequencies are synthesized from standard line transmission by the use of silicon, solid- state inverters. These inverters require switches capable of holding off 6-10 kV, conducting approximately 10 kA for >1 μs at repetition rates of approximately 1 kHz. At present, most inverters use silicon gate turn-off thyristors (GTOs) made by manufacturers such as ABB of Switzerland. Some applications require the use of more than one GTO in series to provide the required voltage hold-off. That GTOs are unipolar devices requires the use of pairs of GTOs to switch both polarities in each cycle of line power. This increases complexity and reduces switch reliability.

The power distribution industry has pursued advanced silicon thyristor designs to meet the demands of high voltage, high power switching systems. Typical of the state of the art devices are high power GTOs (gate turn-off thyristors) and LTTs (light triggered thyristors). Single devices have voltage and current ratings of ~5 kV and 1-2 kA respectively. The die area is typically 20-50 cm² that results in a current density of about

50A/cm². The problem with the use of silicon junction devices is that they do not operate well above approximately 200 °C. In order to utilize silicon devices in high voltage power transmission systems, 10 to 25 devices need to be connected in series.

The motivation to develop light triggered devices arose in large part due to the complexity of the triggering schemes required for simultaneously triggering the devices coupled in series electrically. Fewer units would be required in series arrangements with consequently less complex triggering and cooling arrangements. To this end, thyristors are used to build 10 kV devices. In particular, one known approach involves using liquid nitrogen cooling of the device which would allow the use of a thicker piece of silicon with its additional voltage hold-off capability while still maintaining adequate cooling.

Another technique seeks to improve on the quality control of the silicon by reducing the thickness of the die to achieve reliable operation at 70-90% of the bulk material breakdown strength of silicon. These approaches are expected to yield continuing incremental improvements to silicon based devices. Silicon Carbide (SiC) is a semiconductor material being explored as an alternative to Silicon. Because of its wide bandgap (-3.0 eV) it can withstand higher operating temperatures than silicon. A number of small area prototype SiC devices have been reported in recent years. Though many of the devices reported in the literature exhibit very promising area-normalized electrical performance (i.e. A/cm , W/mm etc.) micropipe defects present in the SiC wafers have prevented small area prototype power devices from being scaled up to useful large area (i.e., greater than 1 mm²) multi-amp power devices. However, the highest known power SiC devices demonstrated switching of 4.2 kW (6 A at 700 V blocking) with a forward voltage drop of 3.9 V. An ideal solid state switch is capable of operating at voltages of approximately 1-

100 kV and is able to switch approximately 1-100 kA at repetition rates from single pulse to around 10^ Hertz. Such solid state switches would have a low switch inductance and low inductance variation from shot to shot. It would also have very low jitter that would allow efficient addition of current from several parallel capacitor banks without degradation of the inherent rise time of the current from each of the individual banks.

A synthetic diamond switch in accordance with the present invention provides performance close to the desired ideal conditions. Unlike junction semi-conductor switches, the synthetic diamond membrane does not exhibit avalanche breakdown, in which an initial seed charge injection from a trigger or "gate" pulse results in exponentially increasing charge injection from the cathode terminal of the external circuit.

Such avalanche breakdown sustains current conduction in junction semi-conductor switches even after the trigger or gate pulse has been turned off. This makes controlled turn-off of such switches difficult. By contrast, in the synthetic diamond switch in accordance with the present invention, when the trigger source (particles or radiation) is turned off, the charge carriers produced by this trigger source recombine almost instantly

(in less than 1 ns) and the specific resistance of the membrane increases rapidly from its low "on state" value to its high "off state" value.

Moreover, in contrast to a junction semi-conductor switch which has a preferred direction for conduction of current, the synthetic diamond switch in accordance with the present invention allows current from the external circuit to flow equally well in either direction, with the same "on state" specific resistance. The superior electrical and thermal properties of synthetic diamond membranes relative to silicon junction semi-conductors makes the subject of this invention a high voltage, bi-directional switch with rapid turn-on and turn-off at repetition rates approaching 1-10 GHz and capable of operation at elevated temperatures up to 700 °K or more, without degradation in on-state specific resistance.

Diamond's superior thermal properties and fast turn-on/turn-off make it well suited to high repetition rate, high power applications. The switch conducts when energy from electrons, ultraviolet photons or other radiation sources including soft and hard x-rays, gamma rays, alpha particles, other types of ions, neutrons or other sub-atomic particles hereafter referred to as particles or radiation, is absorbed within the diamond. Accordingly, in accordance with one embodiment of the present invention, there is provided a triggered diamond switch that approaches the afore-mentioned properties. Diamond has unique properties that make it an ideal material for use in a high power, high repetition rate switch, particularly for high temperature applications. Diamond has an extremely high electrical breakdown strength (-10 MV/cm) which allows for high voltage switches in compact packages. Diamond is a very wide bandgap (5.5 eV) material. The wide bandgap not only reduces the leakage current but allows the fabrication of devices that are not semiconductor, junction type devices. Because diamond is not doped to act like a semiconductor, it switches from its normal insulator state to conducting state. This in turn permits bipolar conduction in diamond devices which provides a further advantage over junction switches.

In addition, diamond's superior thermal properties and fast turn-on/turn-off make it well suited to high repetition rate, high power applications. The switch conducts when energy from particles or radiation is absorbed within the diamond. Conduction ceases upon the cessation of the incident particles or radiation. No avalanche effects have been observed. This makes the switch a potentially superior candidate for high repetition rate applications. Accordingly, the present invention is directed to two improvements over existing particle or radiation detectors. Just as the diamond, by rapid changes in resistance, allows control of the power flowing in an external circuit, the same resistance changes may also be used in an electrical circuit to measure the flux or dose delivered to the diamond by the incident particles or radiation. Presently known approaches include the use of graphite layers as disclosed in U.S. Patent Nos. 4,465,932 and 5,097,133 ('"133 patent"), gold beads under compression as disclosed in the '133 patent, or adhesive silver epoxy as disclosed in U.S. Patent No. 4,833,328, or silver paint as disclosed in the '133 patent to connect two opposite faces of the diamond to the terminals of an external circuit. In contrast, in accordance with the present invention, there is provided a new technique for making such electrical contacts.

SUMMARY OF THE INVENTION

In view of the foregoing, a switch member in accordance with one embodiment of the present invention includes a diamond membrane having first and second surfaces; a first metallic film having a first predetermined thickness deposited on each of said first and second surfaces of said diamond membrane; a second metallic film having a second predetermined thickness deposited on said first metallic film on said first and second diamond membrane surfaces; and a third metallic film deposited on said second metallic film on said first and second diamond membrane surfaces, said third metallic film deposited on said first and second surfaces being different in thickness. A switch member in accordance with another embodiment of the present invention includes a conducting substrate; a diamond membrane having a surface, said diamond membrane conformally grown on said conducting substrate configured to electrically conduct with said substrate; a first metallic film having a first predetermined thickness deposited on said diamond membrane surface; a second metallic film having a second predetermined thickness deposited on said first metallic film on said diamond membrane surface; and a third metallic film deposited on said second metallic film on said diamond membrane surface. A switch member in accordance with yet another embodiment of the present invention includes a hybrid substrate having a conducting portion; a diamond membrane a surface, said diamond membrane conformally grown on said hybrid substrate configured to electrically conduct with said conducting portion of said substrate; a first metallic film having a first predetermined thickness deposited on said diamond membrane surface; a second metallic film having a second predetermined thickness deposited on said first metallic film; and a third metallic film deposited on said second metallic film.

Moreover, an apparatus for switching electrical signals in accordance with one embodiment of the present invention includes a housing including a chamber; a diamond membrane having first and second surfaces coated with a plurality of conductive elements, said membrane positioned in said chamber; a plurality of terminals coupled to said first and second surfaces of said membrane, respectively; a positioning member configured to position said membrane in said chamber, said positioning member further configured to accommodate physical displacement of said membrane; a trigger member provided at a distal position from said diamond membrane first surface configured to provide trigger source to said first surface; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further, wherein said first and second surfaces of said diamond membrane selectively provides electrical conduction to said plurality of terminals in accordance with the trigger source. An apparatus for switching electrical signals in accordance with another embodiment of the present invention includes a housing including a chamber; a conducting substrate positioned in said chamber; a diamond membrane having a surface coated with a plurality of conductive elements, said membrane conformally grown on said conducting substrate wherein said membrane is configured to electrically conduct with said substrate; a plurality of terminals coupled to said diamond membrane surface and said conducting substrate, respectively; a positioning member configured to position said membrane and said substrate in said chamber, said positioning member further configured to accommodate physical displacement of said membrane; a trigger member provided at a distal position from said diamond membrane surface configured to provide trigger source to said surface; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further, wherein said diamond membrane surface and said conducting substrate selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source. An apparatus for switching electrical signals in accordance with yet another embodiment of the present invention includes a housing including a chamber; a hybrid substrate having a conducting portion positioned in said chamber; a diamond membrane having a surface coated with a plurality of conductive elements, said membrane conformally grown on said hybrid substrate wherein said membrane is configured to electrically conduct with said hybrid substrate conducting portion; a plurality of terminals coupled to said diamond membrane surface and said hybrid substrate conducting portion, respectively; a positioning member configured to position said membrane and said substrate in said chamber, said positioning member further configured to accommodate physical displacement of said membrane; a trigger member provided at a distal position from said diamond membrane surface configured to provide trigger source to said surface; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further, wherein said diamond membrane surface and said hybrid substrate conducting portion selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source. An apparatus for switching electrical signals in accordance with yet another embodiment of the present invention includes a housing including a chamber; a first diamond membrane having first and second surfaces coated with a plurality of conductive elements, said first membrane positioned in said chamber; a second diamond membrane having first and second surfaces coated with a plurality of conductive elements, said second membrane positioned in said chamber; a plurality of terminals coupled to said first and second surfaces of said first and second membranes, respectively; a plurality of grading members respectively coupled to said first and second membranes configured to provide substantially uniform electrical field across said first and second diamond membranes; a positioning member configured to position said first and second membranes in said chamber, said positioning member further configured to accommodate displacement of said membranes; a trigger portion provided at a distal position from said first surfaces of said first and second diamond membranes configured to provide a trigger source to said first surfaces; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further, wherein said first and second surfaces of said first and second membranes are configured to selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source. An apparatus for switching electrical signals in accordance with a further embodiment of the present invention includes a housing including a chamber; a first conducting substrate positioned in said chamber; a first diamond membrane having a surface coated with a plurality of conductive elements, said first membrane conformally grown on said first conducting substrate wherein said first membrane is configured to electrically conduct with said first substrate; a second conducting substrate positioned in said chamber; a second diamond membrane having a surface coated with a plurality of conductive elements, said second membrane conformally grown on said second conducting substrate wherein said second membrane is configured to electrically conduct with said second substrate; a plurality of terminals coupled to said first and second membrane surfaces and said first and second substrates; a plurality of grading members respectively coupled to said first and second membranes configured to provide substantially uniform electrical field across said first and second membranes; a positioning member configured to position said first and second membranes in said chamber, said positioning member further configured to accommodate displacement of said membranes; a trigger portion provided at a distal position from said surfaces of said first and second diamond membranes configured to provide a trigger source to said surfaces; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further, wherein said first and second membrane surface and said first and second substrates are configured to selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source.

An apparatus for switching electrical signals in accordance with yet another embodiment of the present invention includes a housing including a chamber; a first hybrid substrate having a conducting portion positioned in said chamber; a first diamond membrane having a surface coated with a plurality of conductive elements, said first membrane conformally grown on said first hybrid substrate wherein said first membrane is configured to electrically conduct with said first substrate conducting portion; a second hybrid substrate having a conducting portion positioned in said chamber; a second diamond membrane having a surface coated with a plurality of conductive elements, said second membrane conformally grown on said second hybrid substrate wherein said second membrane is configured to electrically conduct with said second substrate conducting portion; a plurality of terminals coupled to said first and second membrane surfaces, and said first and second substrate conducting portions; a plurality of grading members respectively coupled to said first and second membranes configured to provide substantially uniform electrical field across said first and second membranes; a positioning member configured to position said first and second membranes in said chamber, said positioning member further configured to accommodate displacement of said membranes; a trigger portion provided at a distal position from said first and second diamond membrane surfaces configured to provide a trigger source to said surfaces; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further, wherein said first and second membrane surfaces and said conducting portions of said first and second substrates are configured to selectively provide electrical conduction to said plurality of terminals in accordance with said trigger source.

Accordingly, the present invention provides a thin, synthetic diamond membrane which is coated with conducting contacts, bonds or holds which position the coated membrane to allow terminals of an external electrical circuit to be connected to the contacts and irradiates one or both faces of the membrane with electrons, ultraviolet photons or other radiation sources including soft and hard x-rays, gamma rays, alpha particles, other types of ions, neutrons or other sub-atomic particles or external trigger source referred to as incident particles or radiation, to produce electron-hole pairs within the bulk of the membrane. The energy deposited in the coated diamond membrane by the external trigger source drastically reduces the resistance of the coated diamond membrane from its normal "OFF' state, with a specific resistance of greater than 10¹² Ω-cm², to an "ON" state with lower than 20 mΩ-cm² specific resistance. This change in resistance allows the coated diamond membrane to conduct current from the external circuit and behave as an electrical switch or as a detector of incident particles or radiation. The technique as illustrated in accordance with the present invention for soldering/brazing/spot welding electrical contacts to the synthetic diamond when used as a detector of atomic particles or radiation above 100 keV permits a reliable and robust diamond detector for use in electron beam sterilization machines, intense ion/electron beam accelerators and radiation treatment. In particular, the soldered/brazed/spot welded contacts preserve a substantially linear relationship between voltage applied to the contacts and the corresponding current through the diamond, even when the diamond and contacts are subject to extremely large doses of penetrating particles or radiation. By contrast, non- soldered/non-brazed/non-spot welded contacts, such as conducting epoxies and silver paint change the contact resistance with accumulated dose. Moreover, the soldered, brazed or spot welded contacts allow for a more compact packaging with less metal surrounding the diamond than compression fittings such as gold beads under compression on graphite layers on the diamond, thus reducing the spurious signal from the excess metal surrounding the diamond.

The stacking of discrete diamond elements that are electrically isolated from one another permits ultra-fast, dose versus depth detectors. For example, a stack of N discrete, 1 mm diamond cubes is capable of producing different currents from each detector in the stack as a flux of penetrating radiation (>100 keV) deposits different doses in each element. From such a depth versus dose distribution, the energy distribution and/or spatial distribution of the incident radiation flux may be determined.

A detector with soldered electrical contacts in a housing suitable for soft x-rays (0.1 - 25 keV) is already commercially available from Alameda Applied Sciences Corporation of San Leandro, California, the assignee of the present application. However, for atomic particles or penetrating radiation above 100 keV the metal and insulator mass around the diamond in this commercial detector makes it unsuitable due to spurious signals. Accordingly, the present invention is directed to a soldering/brazing/spot welding procedure that is designed to minimize the mass of metal around and near the diamond element to make its response dominated by the diamond and thus provide a more reliable and linear response to the incident particles or radiation.

While the techniques involved in the deposition of thin metallic films typically comprising 600 A of Titanium (Ti), followed by 1,200 A of Platinum (Pt), followed by 10,000 A of gold (Au) is known, for example, as disclosed in L.S. Pan, et al., Diamond Rel. Matl, Vol.2, p.820 (1993), the approach in accordance with the present invention further refines a soldering/brazing/spot welding procedure that makes the diamond a more reliable, stable and robust detector of atomic particles or ionizing radiation above 100 keV. In particular, in accordance with the present invention, there is provided a technique which includes soldering, brazing or spot welding different metals such as copper, gold or stainless steel and so on to thin metallic films that have been deposited on the diamond faces.

The present invention also relates to a new configuration of diamonds that allows spectral or spatial resolution of the incident radiation, particularly for energies above 100 keV. For example, a linear stack of diamonds separated electrically allows currents to be measured at several points along the trajectory of the penetrating particles or radiation. These currents provide a dose versus depth history, which in turn gives information about the energy distribution and/or the spatial distribution of the incident particles or radiation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a monolithc diamond switch with a free-standing synthetic diamond membrane in accordance with one embodiment of the present invention.

FIG. 2 illustrates a monolithic diamond switch with a conformally grown synthetic diamond membrane on a conducting substrate in accordance with another embodiment of the present invention.

FIG. 3 illustrates a monolithic diamond switch with a conformally grown synthetic diamond membrane on a hybrid, insulator/conductor substrate in accordance with yet another embodiment of the present invention.

FIG. 4 illustrates a monolithic, diamond membrane switch with an electron beam trigger source in accordance with one embodiment of the present invention.

FIG. 5 illustrates a monolithic, diamond membrane switch with an ultraviolet photon trigger source in accordance with another embodiment of the present invention.

FIG. 6 illustrates a diamond membrane switch in a series, back-to-back configuration with separate electron beam trigger sources in accordance with another embodiment of the present invention.

FIG. 7 illustrates a diamond membrane switch in a series, back-to-back configuration with separate ultraviolet photon trigger sources in accordance with another embodiment of the present invention. FIG. 8 illustrates a diamond membrane switch in a series switch configuration with a common electron beam trigger source in accordance with yet another embodiment of the present invention.

FIG. 9 illustrates a diamond membrane switch in a series switch configuration with a common ultraviolet photon trigger source in accordance with yet another embodiment of the present invention.

FIG. 10 illustrates diamond membrane switch in a parallel switch configuration with a common electron beam trigger source in accordance with still another embodiment of the present invention. FIG. 11 illustrates a diamond membrane switch in a parallel switch configuration with a common ultraviolet photon trigger source in accordance with still another embodiment of the present invention.

FIG. 12 demonstrates a trace of current versus time in an electrical circuit that includes the synthetic diamond switch of the present invention. FIG. 13 illustrates the on-state specific resistance of the synthetic diamond switch of the present invention as a function of electron beam energy for a number of different thickness diamond membranes.

FIG. 14(a) provides a conceptual illustration of the magnetic deflection.

FIG. 14(b) illustrates three current traces showing the natural extinction of the electron source and the effect of the deflection coil on the opening of the diamond switch of the present invention.

FIG. 15 illustrates the synthetic diamond membrane switch of the present invention as a fast, high power RF switch and a RF amplitude and phase controller.

FIG. 16 illustrates an electrical circuit for the diamond-opening switch as an inductive energy store power amplifier in accordance with the present invention.

FIG. 17 shows the time histories of the resistance of the synthetic diamond opening switch (DIMOS) in accordance with one embodiment of the present invention with a 1 Ω bremsstrahlung diode the load.

FIG. 18 shows the time histories of the total current and the load (bremsstrahlung diode) current with the diamond opening switch DIMOS as shown driving a 1-Ω bremsstrahlung diode.

FIG. 19 shows the time histories load current, voltage and energy with the diamond opening switch as shown driving a 1-Ω bremsstrahlung diode. FIG. 20(a) shows the scaling of conduction current with increase in device active area.

FIG. 20(b) shows the on-state specific resistance staying constant with increase in conduction current. FIG. 21 shows the on-state specific resistance as a function of temperature up to

375 °C (648 °K).

FIG. 22 shows the signal obtained from a diamond detector with soldered electrical contacts at three different times. The first point shows the response to a dose of 12 MeV electrons when the diamond was new. The next two points show its response to the same electron dose, but after the detector had accumulated total electron irradiation doses of 5 and 10 MGy, respectively.

FIG. 23 shows a stack of N discrete diamond elements that give N discrete currents in response to an incident flux of the particles or radiation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 1 illustrates a synthetic diamond membrane assembly in accordance with one embodiment of the present invention. As shown, there is provided a single (monolithic) synthetic diamond membrane 1 that is provided between two conducting terminals 2 and 3. The diamond membrane 1 has an upper surface 1 A and a lower surface IB both of which are coated. In particular, the upper surface 1 A of the diamond membrane 1 is coated with layers of titanium, platinum and gold of approximate thickness of 200 A, 200 A, and 1,000 A, respectively, while its lower surface IB is coated with layers of titanium, platinum, and gold of approximate thickness of 200 A, 200 A, and 10,000 A, respectively. Both the upper and lower conducting terminals 2 and 3 may be bonded to the surfaces 1 A and IB of the diamond membrane 1, or may be held in compression fitting. The compression fitting ensures electrical contact to the diamond metal surfaces without being rigidly bonded to the surfaces 1 A and IB. Moreover, as discussed in further detail below, either an electron beam trigger or an ultraviolet light trigger may be used to trigger the synthetic diamond membrane 1. Figure 2 illustrates a synthetic diamond membrane assembly in accordance with another embodiment of the present invention. As shown, there is provided a single (monolithic) synthetic diamond membrane 1 that is conformally grown on a conducting substrate 2. The diamond membrane 1 has an upper surface 1 A coated as described in Figure 1 above. The lower surface IB of the diamond membrane 1 is conformally grown on the conducting substrate 2 and is therefore in electrical contact therewith. More specifically, the upper surface 1A of the diamond membrane 1 is coated with layers of titanium, platinum, and gold of approximate thickness of 200 A, 200 A, and 1,000 A, respectively. Moreover, the conformal growth on the conducting substrate 2 substantially eliminates the problem of surface flashover from the conducting substrate 2 to the upper conducting terminal 3 by increasing the path length of such flashover. The upper conducting terminal 3 may be bonded to the diamond membrane 1 or held in a compression fitting as described below with respect to the embodiment of the diamond switch assembly shown in Figure 4. Moreover, as discussed in further detail below, either an electron beam trigger or an ultraviolet light trigger may be used to trigger the synthetic diamond membrane.

Figure 3 illustrates a synthetic diamond membrane assembly in accordance with yet another embodiment of the present invention. In this embodiment, the diamond membrane 1 is conformally grown on a hybrid insulating/conducting substrate 2 to further eliminate the problem of surface flashover from the hybrid substrate 2 to the upper conducting terminal 3. The hybrid substrate 2 is more effectively in reducing or eliminating surface flashover because of the greater insulating distance provided between the opposite conducting terminals 3 and 4 of the diamond switch. Moreover, as with the embodiment shown in Figure 2, the upper surface 1 A of the diamond membrane 1 is likewise coated with titanium, platinum and gold as discussed above.

Furthermore, the upper conducting terminal 3 may be bonded to the diamond membrane 1 or held in a compression fitting as described in further detail below. Also, either the electron beam trigger or the ultraviolet light trigger may be used to trigger the synthetic diamond membrane. Figure 4 illustrates the overall assembly of the diamond switch in accordance with one embodiment of the present invention. As shown, there is provided a synthetic diamond membrane 1 such as one illustrated in either Figures 1, 2, or 3 of the present application which is placed in a vacuum envelope 2. The metal coatings on the upper and the lower surfaces 3 and 4 of the diamond membrane 1 are connected to a pair of parallel electrodes by a plurality of compression contacts 5, 6, respectively. The pair of parallel electrodes emerges from the vacuum envelope 2 and is connected to the two terminals of an external current source 7. Accordingly, the diamond membrane 1 is configured to operate as a switch and is triggered into conduction by an electron trigger source 8 which includes a cathode 9, a grid 10 and a focusing tube 11. The cathode 9 emits electrons that are supplied by the external power supply 12. The focusing tube 11 collimates and/or focuses the electrons and directs them on to the upper surface 3 of the diamond membrane

1.

Without the electrons from the electron source 8, the diamond membrane 1 provides very high resistance to the external circuit 7 and negligible current flows. For example, a 1-cm active area switch provides a resistance of approximately 10 Ω, such that when a voltage of 25 kV is applied across the diamond membrane 1, only 25 nA of current is allowed to flow, thus providing the "OFF" state of the diamond switch. On the other hand, the energy absorbed from the electrons by the diamond membrane 1 reduces the resistance of the membrane and allows much larger currents to flow. For example, a 1 cm² active area switch is reduced in resistance from 10¹² Ω to 20 mΩ such that the current that flows is now limited by the total resistance of the external circuit 7. With such an external resistance of, for example, 25 Ω, a forward current of 1 ,000 A will flow across the diamond membrane 1 to provide a forward current density of 1 kA/cm², thus providing the "ON" state of the diamond switch.

Figure 5 illustrates the overall assembly of the diamond switch in accordance with another embodiment of the present invention. As shown, the upper surface 2 of the diamond membrane 1 is coated with layers of titanium, platinum and gold of thickness of approximately 200 A, 200 A, and 1,000 A, respectively, where these metallic coatings partially cover the upper surface 2 of the diamond membrane 1. The diamond membrane

1 is further coated on its lower surface 3 with layers of titanium, platinum and gold of thickness of approximately 200 A, 200 A, and 10,000 A, respectively. These metal coatings are connected to a pair of parallel electrodes by a plurality of compression contacts 4 and 5. The pair of parallel electrodes emerges from the diamond membrane 1 and is connected to the two terminals of the external current source 6.

Accordingly, the diamond membrane 1 configured as a switch is triggered into conduction by an ultraviolet photon source 7. This photon source 7 may be either a gas discharge source or a semi-conductor diode source, and is powered by the external power supply 8. There is also provided a collimating lens 9 which collimates and/or focuses the photons and directs them on to the upper surface 2 of the diamond membrane 1. The ultraviolet photons pass through the transparent portions of the metal coating on the upper surface 2 of the diamond membrane 1 and are absorbed by the membrane 1. Without the photons from the photon source 7, the diamond membrane 1 provides a very high resistance to the external circuit 6 and negligible current flows. For example, a 1 cm² active area switch has a resistance of approximately 10¹² Ω, such that when a voltage of 25 kV is applied across the membrane, only 25 nA of current is allowed to flow, thus providing the "OFF' state of the switch. On the other hand, the energy absorbed from the photons by the diamond membrane 1 reduces the resistance of the membrane 1 and allows much larger currents to flow. For example, a 1 cm² active area switch is reduced in resistance from 10¹² Ω to 20 mΩ. The current that flows is now limited by the total resistance of the external circuit 6. If this total resistance were 25 Ω, a forward current of 1,000 A would flow across the diamond membrane 1 to provide a forward current density of 1 kA/cm², thus providing the "ON" state of the switch.

Figure 6 shows the overall diamond switch assembly in accordance with another embodiment of the present invention. As shown, there is provided a first diamond membrane 1 coated on its upper surface 2 with thin layers of titanium, platinum, and gold with approximate thickness of 200 A, 200 A and 1,000 A, respectively. Moreover, as with previous embodiments, the diamond membrane 1 is further coated on its lower surface 3 with layers of titanium , platinum and gold with approximate thickness of 200 A, 200 A and 10,000 A, respectively. The lower surface 3 of the first diamond membrane 1 is positioned on a solid copper block 4 which serves as a heat sink and as the series electrical connection between the first diamond membrane 1 and a second diamond membrane 5.

The upper surface 6 of the second diamond membrane 5 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A, and 10,000 A, respectively. Moreover, the lower surface 7 of the second diamond membrane 5 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A, and 1,000 A, respectively.

Also provided in the diamond switch assembly illustrated in Figure 6 are two electron guns, 8 and 9 which respectively direct beams of trigger electrons to the metallic surfaces 2 and 7 of the respective diamond membranes 1 and 5. The two electron guns 8 and 9 are powered by a common power supply 10. Further shown are two control grids 11 and 12 of the two electron guns 8 and 9 which are connected to a common grid power supply 13, which ensures that the turn-on and turn-off of the trigger electron pulses are synchronous. This synchronism between the two separate electron triggers ensures simultaneous switching of the two diamond membranes 1 and 5. In turn, simultaneous switching ensures against adverse effects of jitter between the two separate trigger pulses, where one switch might turn on before the other, temporarily causing the fully applied voltage to appear across the second switch, with potential for failure of that switch due to excessive electrical stress. As shown, the embodiment of the diamond switch assembly illustrated in Figure 6 is a series, back-to-back, electron beam triggered switch configuration. Accordingly, the overall voltage hold-off of this configuration is twice as high as that for each switch element on its own. An advantage of the use of two separate electron guns with independent grids is the ability to deliberately delay one electron trigger with respect to the other. For example, if the diamond membranes 1 and 5 are not identical and one inherently turns on earlier than the other, then by adjusting the delay between triggers, the switching on of both membranes 1 and 5 may be forced into co-incidence.

Each of the two diamond membranes 1 and 5 also has a metal grading ring (14 and 15) as shown in Figure 6. The metal grading rings 14 and 15 provide uniformity in electrical field around and across the diamond membranes 1 and 5. This is achieved by connecting the grading rings 14 and 15 to the high and low voltage surfaces of the membrane (2 and 3 or 6 and 7, respectively), via a passive resistive/capacitive divider network (16 or 17). This passive resistive/capacitive divider network pulls the potential at the grading ring to approximately 50% of the applied potential across each diamond membrane 1 and 5, which, in turn, evens out the electrical field around and across the membranes 1 and 5. With a nearly uniform field distribution across and around the membranes 1 and 5, the switches can hold higher voltages than without such grading. Depending upon the details of the switch geometry, the optimum voltage at the grading ring may be greater or lesser than 50%. An electrostatic field solver code is used to calculate the optimum ratio of resistance/capacitance in the passive resistive/capacitive divider networks 16 and 17.

Figure 7 shows the overall assembly of the diamond switch configuration in accordance with another embodiment of the present invention. As shown, there is provided a first diamond membrane 1 coated on its upper surface 2 with layers of titanium, platinum and gold of approximate thickness of 200 A, 200 A, and 1,000 A, respectively.

These metallic coatings only partially cover the upper surface 2 of the diamond membrane 1 to allow the ultraviolet trigger radiation to penetrate the diamond membrane 1. The first diamond membrane 1 is further coated on its lower surface 3 with layers of titanium, platinum and gold of approximate thickness of 200 A, 200 A, and 10,000 A, respectively. The lower surface 3 of the first diamond membrane 1 is positioned on a solid copper block 4 which serves as a heat sink and as the series electrical connection between the first diamond membrane 1 and a second diamond membrane 5. The upper surface 6 of the second diamond membrane 5 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 10,000 A, respectively, while the lower surface 7 of the second membrane 5 is coated with thin layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A, and 1,000 A, respectively. As with the first diamond membrane 1 , these metallic coatings only partially cover the upper surface 6 of the second diamond membrane 5 to allow the ultraviolet trigger radiation to penetrate the second diamond membrane 5.

Accordingly, the diamond membrane switches 1 and 5 are triggered into conduction by ultraviolet photon sources 8 and 9. The photon sources may be either gas discharge sources or semi-conductor diode sources, and are powered by a common external power supply 10. The collimating lenses 11 and 12 collimate and/or focus the photons and direct them on to the partially transparent surfaces 2 and 7 of the respective diamond membranes 1 and 5. The use of a common power supply 10 for the two separate ultraviolet light trigger sources ensures that the turn-on and turn-off of the two series switches are synchronous.

Again, if there is jitter between the two separate ultraviolet light trigger sources, one switch may turn on before the other, temporarily causing the full applied voltage to appear across the second switch with potential for failure of that switch due to excessive electrical stress. Accordingly, an advantage for using two separate ultraviolet sources with a common power source is to deliberately delay one source with respect to the other by introducing a controllable delay in the power supply 10. For example, if the two diamond membranes 1 and 5 are not identical and one inherently turns on earlier than the other, then by adjusting the delay between sources, the turn-on of both diamond membranes 1 and 5 may be forced into coincidence.

Moreover, each of the two diamond membranes 1 and 5 also has a metal grading ring 13 and 14 which provides uniformity of electrical field around and across the diamond membranes 1 and 5. As before, this is achieved by connecting the grading rings

13 and 14 to the high and low voltage surfaces of the membrane (2 and 3, or 6 and 7), via a passive resistive/capacitive divider network (15 or 16). This passive resistive/capacitive divider network pulls the potential at the grading ring to approximately 50% of the applied potential across each membrane, which in turn evens out the electrical field around and across the membrane. With a nearly uniform field distribution across and around the membrane, the switch can hold higher voltages than without such grading. Depending upon the details of the switch geometry, the optimum voltage at the grading ring may be greater or lesser than 50%. An electrostatic field solver code is used to calculate the optimum ratio of resistance/capacitance in the passive resistive/capacitive divider networks 15 and 16.

As illustrated above, similar to the embodiment shown in Figure 6, the diamond switch assembly of Figure 7 is a series, back-to-back, ultraviolet light triggered switch configuration where the overall voltage hold-off is twice as high as that for each switch element on its own.

Figure 8 illustrates the diamond switch assembly in accordance with yet another embodiment of the present invention. This is a series, side-by-side, electron beam triggered switch configuration with the overall voltage hold-off being twice as high as that for each switch element on its own. As shown, there is provided a first diamond membrane 1 having it upper surface 2 coated with layers of titanium, platinum and gold having approximate thickness of 200 A , 200 A , and 1,000 A, respectively, and its lower surface 3 coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 10,000 A, respectively. The lower surface 3 of the first membrane 1 is positioned on a metal strip 4 which serves as the series electrical connection between the first diamond membrane 1 and an upper surface 5 of a second diamond membrane 6. The upper surface 5 of the second diamond membrane 6 is likewise coated with layers of titanium, platinum and gold of approximate thickness of 200 A, 200 A and 10,000 A, respectively, while the lower surface 7 of the second diamond membrane 6 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 1,000 A, respectively.

There is further provided a single electron gun 8 which is configured to direct a beam of trigger electrons to the thin metallic surfaces 2 and 5 of the respective diamond membranes 1 and 6. The electron gun 8 is connected to a power supply 9 while its control grid 10 is connected to a grid power supply 11. The main difference between the back-to- back series switch configuration described in Figure 7 and the present side-by-side configuration is the use of a single electron gun to trigger both switches. The jitter in turn- on of the two switches is no longer dependent on the synchronism of two separate electron guns or gate pulses. Provided that the two diamond membranes 1 and 6 are substantially identical in turn-on characteristics, this synchronism between the two separate electron triggers ensures that the two-diamond membrane switch assembly (1 and 6) will turn on simultaneously. If there is jitter between the two separate trigger pulses, one switch may turn on before the other, temporarily causing the fully applied voltage to appear across the second switch, with potential for failure of that switch due to excessive electrical stress. Each of the two diamond membranes 1 and 6 also has a metal grading ring (14 and

15) as shown in the figure. As previously discussed, the grading rings provide uniform electrical field around and across the diamond membranes 1 and 6. This is achieved by connecting the grading rings to the high and low voltage faces of the membrane (2 and 3 or 6 and 7), via a passive resistive/capacitive divider network (16 or 17). This passive resistive/capacitive divider network pulls the potential at the grading ring to approximately

50% of the applied potential across each membrane, which, in turn, evens out the electrical field around and across the membrane. With a nearly uniform field distribution across and around the membrane, the switch can hold higher voltages than without such grading. Depending upon the details of the switch geometry, the optimum voltage at the grading ring may be greater or lesser than 50%. Accordingly, an electrostatic field solver code can be used to calculate the optimum ratio of resistance/capacitance in the passive resistive/capacitive divider networks 16 and 17.

Figure 9 illustrates a diamond switch assembly in accordance with yet another embodiment of the present invention. Similar to the embodiment of Figure 8, this is a series, side-by-side, ultraviolet light triggered switch configuration where the overall voltage hold-off is twice as high as that for each switch element on its own.

As shown, there is provided a first diamond membrane 1 coated on its upper surface 2 with layers of titanium, platinum and gold of approximate thickness of 200 A, 200 A and 1,000 A, respectively. These metallic coatings only partially cover the upper surface 2 of the diamond membrane 1 to allow the ultraviolet trigger radiation to penetrate the first diamond membrane 1. Moreover, the first diamond membrane 1 is further coated on its lower surface 3 with layers of titanium, platinum and gold of approximate thickness of 200 A, 200 A and 10,000 A, respectively. The lower surface 3 of the first membrane 1 is positioned on a metal strip 4 which serves as the series electrical connection between the first membrane 1 and an upper surface 5 of a second diamond membrane 6.

The upper surface 5 of the second diamond membrane 6 is coated with layers of titanium, platinum, and gold having approximate thickness of 200 A, 200 A and 10,000 A, respectively, while the lower surface 7 of the second diamond membrane 6 is coated with layers of titanium, platinum, and gold having approximate thickness of 200 A, 200 A and 1,000 A, respectively.

A single ultraviolet light source 8 directs a beam of photons to the partially transparent metallic surfaces 2 and 5 of the two diamond membranes 1 and 6. This light source is connected to a power supply 9. The main difference between the back-to-back series switch configuration described in Figure 7 and this side-by-side configuration is the use of a single ultraviolet light source to trigger both switches. As with the embodiment of Figure 8, the jitter in turn-on of the two switches is no longer dependent on the synchronism of two separate light sources. Provided that the two membranes are identical in turn-on characteristics, the use of a single light source ensures that the two switch elements 1 and 6 will turn on simultaneously. If there is jitter between the two separate trigger pulses, one switch might turn on before the other, temporarily causing the total applied voltage to appear across the second switch, with potential for failure of that switch due to excessive electrical stress. Each of the two diamond membranes 1 and 6 also has a metal grading ring (14 and

15) as shown in the figure. As before, the grading rings provide uniform electrical field around and across the diamond membranes 1 and 6. This is achieved by connecting the grading rings to the high and low voltage faces of the membrane (2 and 3 or 6 and 7), via a passive resistive/capacitive divider network (16 or 17). This passive resistive/capacitive divider network pulls the potential at the grading ring to approximately 50% of the applied potential across each membrane, which, in turn, evens out the electrical field around and across the membrane. With a nearly uniform field distribution across and around the membrane, the switch can hold higher voltages than without such grading. Depending upon the details of the switch geometry, the optimum voltage at the grading ring might be greater or lesser than 50%. Thus, an electrostatic field solver code can be used to calculate the optimum ratio of resistance/capacitance in the passive resistive/capacitive divider networks 16 and 17.

Figure 10 illustrates a diamond switch assembly in accordance with yet another embodiment of the present invention. This is a parallel, side-by-side, electron beam triggered switch configuration where the overall peak conduction current is twice as high as that for each switch element on its own. A first diamond membrane 1 is coated on its upper surface 2 with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A, and 1,000 A, respectively, and further, its lower surface 3 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 10,000 A, respectively. The lower surface 3 of the first diamond membrane 1 is positioned on a metal strip 4 which serves as the parallel electrical connection between the first diamond membrane 1 and a lower surface 7 of a second diamond membrane 6. The upper surface 5 of the second membrane 6 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 10,000 A, respectively, while the lower surface 7 of the second membrane 6 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 1,000 A, respectively.

A single electron gun 8 directs a beam of trigger electrons to the thin metallic faces 2 and 5 of the two diamond membranes 1 and 6, respectively. The electron gun 8 is connected to a power supply 9 while the control grid 10 of the electron gun 8 is connected to a grid power supply 11. The jitter in turn-on of the two switches 1 and 6 is not dependent on the synchronism of two separate electron guns or gate pulses. Each of the two diamond membranes 1 and 6 also has a metal grading ring (14 and 15) as shown in the figure, connected electrically to each other and held at the same potential. As before, the grading rings provide uniform electrical field around and across the diamond membranes 1 and 6 by connecting the grading rings to the high and low voltage faces of the membrane (2 and 3), via a passive resistive/capacitive divider network (16). The passive resistive/capacitive divider network pulls the potential at the grading ring to approximately 50% of the applied potential across each membrane, which in turn evens out the electrical field around and across the membrane. With a nearly uniform field distribution across and around the membrane, the switch can hold higher voltages than without such grading. Depending upon the details of the switch geometry, the optimum voltage at the grading ring may be greater or lesser than 50%. Thus, an electrostatic field solver code can be used to calculate the optimum ratio of resistance/capacitance in the passive resistive/capacitive divider network 16.

Figure 11 illustrates a diamond switch assembly in accordance with a further embodiment of the present invention. This is a parallel, side-by-side, ultraviolet light triggered switch configuration where the overall peak conduction current is twice as high as that for each switch element on its own. A first diamond membrane 1 is coated on its upper surface 2 with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 1,000 A, respectively, while its lower surface 3 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 10,000 A, respectively. The lower surface 3 of the first membrane 1 is positioned on a metal strip 4 which serves as the parallel electrical connection between the first membrane 1 and the lower surface 7 of a second diamond membrane 6. The upper surface 5 of the second membrane 6 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 10,000 A, while the lower surface 7 of the second membrane 6 is coated with layers of titanium, platinum and gold having approximate thickness of 200 A, 200 A and 1,000 A, respectively.

A single ultraviolet light source 8 directs a beam of photons to the partially transparent metallic faces 2 and 5 of the two diamond membranes 1 and 6. The light source 8 is connected to a power supply 9. The jitter in turn-on of the two switches is not dependent on the synchronism of two separate light sources. Each of the two diamond membranes 1 and 6 also has a metal grading ring (14 and 15) as shown in the figure. These two grading rings are connected electrically to each other and held at the same potential. As before, the grading rings provide uniform electrical field around and across the diamond membranes. Figure 12 shows a trace of current versus time in an electrical circuit that includes the synthetic diamond switch in accordance with one embodiment of the present invention. The conduction current data of a 100 μm thick CVD device biased initially to 15 kV are shown. The conduction current is limited by an external resistor to 12 A. With a 1.2 mm² active area, the conduction current corresponds to a conduction current density of approximately 1 kA/cm . The switch is triggered using an electron beam generated using an externally applied bias across a carbon fiber cathode and mesh anode within a vacuum chamber. It is to be noted that the electron beam is capable of generating a beam with electron energies up to 240 keV with an almost sinusoidal current profile with half period about 1.0 μs. Furthermore, a 0.3 μF capacitor is charged to provide dc voltage to the diamond switch.

The conduction current is measured using a Pearson current transformer. The dashed curve 110 shows the current in the electron beam measured using a Faraday cup located near the diamond while the solid curve 111 illustrates the conduction current through the diamond. The conduction current follows the electron current. The electron current measured by the Faraday cup shows structure in the beam. The reason the conduction current is not affected by this structure is that the electron beam current in these experiments far exceeds the beam current required to efficiently switch the diamond. As long as the beam current stays above this threshold value, diamond conduction persists. These data show turn-on and turn-off times of about 50 ns. By sweeping the electrons on and off, much faster times can be achieved. For example, an approximately 5 ns turn-off can be achieved by sweeping the electrons with a small magnetic field. The on-state resistance is determined by measuring the conduction current at several different dc bias voltages and plotting a graph of current I versus voltage V. The slope of this I-V curve provides the total circuit resistance from which the fixed external resistance is subtracted. The remainder is the on-state resistance of the diamond. Due to the smaller active area of the test devices than practical units, the on-state specific resistance is a more meaningful number to compute. For the device whose conduction data are shown in Figure 12, the on-state specific resistance is about 30 mΩ-cm². In practice, this implies that a 25 kV/ 1,000 A device that is based on a 100 μm thick CVD diamond and a 1 cm² active area, would have an on-state resistance of 30 mΩ or an on-state voltage drop of 30 V. If the wafer thickness is reduced from 100 μm to 10 μm, the specific resistance will decrease to 3 mΩ-cm², reducing the on-state voltage drop to 3 volts. Figure 13 shows the on-state specific resistance as a function of electron beam energy for a number of different thickness diamonds in accordance with one embodiment of the present invention. The on-state specific resistance is defined as the on-state resistance of the diamond multiplied by the conduction area. The on-state specific resistance increases as the electron beam energy is reduced for a given diamond thickness. The two abscissas show the peak electron energy and the electron energy at the onset of conduction in the diamond. These data can be used to determine the beam energy required for a given thickness of diamond. The thickness of diamond is, in turn, determined by the hold-off voltage required by the application.

Figure 14(a) shows a conceptual approach for magnetic deflection of the trigger electron beam, while Figure 14(b) illustrates diamond switch conduction as a function of time. Using a magnetic deflection technique, the trigger electron beam is swept off the diamond surface, causing the diamond to increase in resistance, opening the circuit. The diamond is dc biased at 2,000 V switching the power supply to a 50-Ohm load, producing a current of 40 A. There are three current traces shown in Figure 14(b). The widest trace shows the natural extinction of the electron source. The two sharper opening time traces show the effect of the deflection coil on the opening of the diamond switch. With the deflection coils activated, the diamond switch appears to open in about 10 ns. It is to be noted that the opening times may be further reduced by modifying the magnetic coils and driver. However, the hole-pair recombination time in the diamond, which is about 100 ps, may be a limitation to the further reduction in the opening times. Moreover, while magnetic deflection is illustrated above, other techniques to cut-off the trigger source, such as electric deflection of charged particles or fast shutters for electromagnetic radiation, are equally viable.

Figure 15 shows a schematic drawing of an embodiment of the synthetic diamond membrane switch in accordance with the present invention, configured to operate as a fast, high power RF switch and a RF amplitude and phase controller. Rapid changes in the flux and energy of the incident trigger particles or radiation are used to modify the transmission properties of the synthetic diamond membrane such that electromagnetic radiation in the radio-frequency (RF) and microwave regions of the spectrum is transmitted when the diamond is "off but reflected when it is "on". The rapid switching of the transmission properties of the synthetic diamond membrane to RF and microwaves, allows it to be used as a very fast, high power RF switch as well as a RF amplitude and phase controller.

Figure 16 shows a schematic drawing of one embodiment of the electrical circuit incorporating a synthetic diamond membrane as an inductive energy store power amplifier. As shown, there is provided a main capacitor bank of 9.6 μF bank charged to 20 kV in air and storing approximately 2 kJ of energy. This bank charges a vacuum inductor of 50 nH (the capacitor bank and connection inductance is about 10 nH) through an array of diamond opening switches whose on-state resistance is about 16 mΩ. At the peak of the drive current pulse, the diamond switches are triggered to open by reducing the trigger (particles or radiation) flux impinging on the diamond membrane. The rapid opening shunts the current from the switches to the parallel load. A bremsstrahlung x-ray diode is shown in the figure as an example of such a load.

The operating characteristics of the inductive energy storage circuit discussed above are illustrated in Figures 17, 18 and 19. In particular, Figure 17 shows the time histories of the resistance of the synthetic diamond opening switch (DIMOS) of the present invention and a 1 Ω bremsstrahlung diode, that is the load. It is to be noted that the x-ray diode is assumed to be a high impedance that drops to 1 Ω for about 50 ns, then collapses due to plasma build up in the diode. The DLMOS resistance begins at 7.5 mΩ, then rises as shown. The resistance history of the diamond-opening switch is calculated from the measured on-state voltage and conduction current (shown in Figure 12). Figure 18 shows the calculated total current and load current. After a 1,210 ns conduction phase in which 235 kA are delivered to the storage inductor, the diamond switch of the present invention shunts 160 kA to the x-ray diode. At 1,310 ns, the diode shorts out. For this case, about 67% of the upstream current is shunted by the DLMOS to the bremsstrahlung diode. Because the DLMOS resistance history as shown in Figure 17 is for an uncontrolled opening, the results are not optimal. With controlled, more rapid opening such as that shown in Figure 13b, the current transfer efficiency from DIMOS to parallel load can be much higher, limited only by the added inductance between DIMOS and load. Figure 19 shows the current and voltage histories in the x-ray diode load, as well as the electrical energy absorbed by the diode from the storage inductor. The peak voltage on the diode is approximately 160 kV, which slightly leads (in phase) the peak current of 160 kA. Though not shown in this figure, the power pulse has a rise-time of about 10 ns and a full width at half maximum (FWHM) of about 30 ns. This results in a bremsstrahlung x- ray pulse (from a reflection converter, for example) with a rise time of less than 10 ns and about 30 ns FWHM. The end-point voltage of the bremsstrahlung spectrum would be less than 160 keV. The 9.6 μF / 20 kV bank can be assembled in a lm^ volume, making it very compact. The diamond opening switch approach could thus lead to a portable, efficient x-ray source for a variety of applications. The total energy delivered to the diode of approximately 850 J is about 44% of the total stored bank energy. The average load power is 850 J/30 ns which is approximately 28 GWatts. The power input to the DIMOS is 1,920 J/1,210 ns which is roughly 1.6 GWatts. Thus the DIMOS amplifies the power in the circuit by a factor of about 17.

Figure 20(a) shows the scaling of conduction current with increase in device active area. Figure 20(b) shows the on-state specific resistance versus conduction current. One of the key drawbacks of present day SiC high temperature devices is the difficulty (due to micropipe defects) of increasing the active area of the devices beyond the -1 mm² level. However, this is not the case with CVD diamond in accordance with the present invention. In particular, Figure 20(a) shows the scaling of conduction current with increase in device active area up to 12.6 mm². Areas larger than about 1,000 mm² are available in synthetic diamond membranes. The linear dependence suggests that higher currents may be handled by a single diamond switch simply by increasing the active area of the switch. Figure 20(b) shows that the on-state specific resistance stays constant with this increase in conduction current.

Figure 21 shows the on-state specific resistance as a function of temperature, up to 375 °C (648 °K). The operating temperature may be increased beyond the levels demonstrated. Limits in the heater circuit limited our ability to raise the temperature of the devices above 375 °C (648 °K). The CVD devices have been operated at temperatures up to 375 °C. A marginal decrease in the on-state specific resistance is measured as temperature increases.

Figure 22 shows the signal obtained from a diamond detector with soldered electrical contacts at three different times. The first point shows the response to a dose of

12 MeV electrons when the diamond was new. The next two points show its response to the same electron dose, but after the detector has accumulated total electron irradiation doses of 5 and 10 MGy respectively. The slight decrease in sensitivity after 10 MGy is not statistically significant because the data were not taken with adequate statistics. Nevertheless, the nearly constant sensitivity after an accumulated dose of about 10 MGy make diamond detectors far more robust than silicon detectors or other diamond detectors with conducting epoxies or silver paints.

Figure 23 shows two views of a stack of N discrete diamond elements. A diamond 1 is coated with two metallic contacts 2. A twisted pair of electrical cables 4 is soldered, brazed or spot welded 3 to the metallic contacts 2. The diamond 1, the metallic contacts 2, the area 3 and the twisted pair of electrical cables 4 form a single diamond element. Each element is isolated electrically from its neighbor by ensuring that the metallic contact 2 is not coated all the way to the edge of the diamond 1. The multiple diamond elements are stacked as shown in the figure. These N discrete diamond elements provide N discrete currents in response to an incident flux of particles or radiation. From these measured currents, the delivered dose versus depth profile may be obtained. This dose versus depth profile in turn allows the calculation of the energy distribution and/or spatial distribution of the incident particles or radiation.

As discussed above, the synthetic diamond switches in accordance with the present invention provide up to 15 kV hold-off in a monolithic switch, up to 5 kA/cm bidirectional switched current densities with -10 ns controlled turn-on and turn-off times. In addition, the switches in accordance with the present invention provide operations at up to 675 °K with no degradation in on-state conductivity relative to their room temperature operation. When the incident trigger energy (particles or radiation) is turned off, the diamond membrane reverts to its high resistance (off) state almost instantly. The rapid turn-off feature allows the switch to be operated in repetitively pulsed mode at very high repetition frequencies that could approach 10 GHz and gives the diamond a very fast response (approximately 100 ps) as a detector of atomic and sub-atomic particles and radiation.

Diamond switch assemblies as illustrated above in accordance with the various embodiments of the present invention can provide monolithic switches that hold-off up to 50 kV and switch approximately 1 kA/cm² current densities with less than 1 ns turn-on and turn-off times. This type of switch includes a synthetic diamond membrane that has metal ohmic contacts deposited either on opposite surfaces of the membrane or on just one surface, with the trigger energy input (particles or radiation) incident either across one or both surfaces of the diamond membrane, or else incident across the thin dimension of the membrane. This type of switch further includes a source of 'particles or radiation' that is disposed either on one or on opposite sides of the diamond membrane and that irradiates the membrane with particles or radiation of sufficient energy and flux to effect a reduction in resistance of the membrane from its natural high resistance state to a low resistance state by the production of electron-hole pairs within the thickness of the membrane. Furthermore, this type of switch further includes a support structure for the diamond membrane that serves to make it mechanically strong while also preventing the current in the external circuit from flowing along the surface of the membrane rather than across it or through it.

The rapid change in resistance of the synthetic diamond when subjected to irradiation by particles or radiation may also be used to detect the flux of particles or radiation using conventional techniques. In contrast, the present invention relates to a new technique for making electrical contacts to the diamond by soldering, brazing or spot welding to conductive layers deposited on the diamond. The new contacts are more robust, stable and reliable than earlier graphitic or conductive epoxy/paint contacts.

In particular, an embodiment of a detector in accordance with the present invention is previously described which uses a stack of diamonds to allow spectral and/or spatial resolution of the incident radiation, particularly for energies above 100 keV. Currents can be measured at several points along the trajectory of penetrating particles or radiation in a stack of electrically isolated diamonds. These measured currents provide a dose versus depth history, which in turn gives information about the energy distribution and/or the spatial distribution of the incident particles or radiation. Accordingly, the present invention provides an apparatus that switches currents at high voltages from one part of an electrical circuit to another very rapidly in either direction and at very high repetition rates. Moreover, the present invention uses the superior electrical field strength of a synthetic diamond membrane to hold off high voltages. The synthetic diamond membrane may be in several configurations: a freestanding membrane that is held in place by compression contacts; a free-standing membrane that is coated on either one or both surfaces with conducting material and held in a compression fitting; a membrane that is grown conformally on a substrate of a different material that makes the structure mechanically rigid. This substrate structure can be either conducting or a combination of insulators and conducting materials.

Additionally, the present invention provides a thin synthetic diamond membrane positioned in a compression fitting that forms electrical contacts at the input and output of the switch. These inputs and outputs might be on opposite faces of the diamond membrane or on the same face, depending upon the specific embodiment. These input and output terminals of the membrane are connected to an external electrical circuit. In its normal OFF state, the diamond membrane offers extremely high resistance (>10¹² Ω) and negligible electrical current flows through it. Furthermore, in accordance with the present invention, a thin synthetic diamond membrane coated with conducting material on either one or both surfaces is positioned in a compression fitting that forms electrical contacts at the input and output of the switch. These inputs and outputs might be on opposite faces of the diamond membrane or on the same face, depending upon the specific embodiment. The synthetic diamond is coated on one face when both input and output are on the same face. The synthetic diamond is coated on both faces when the input and output are on opposite faces. These input and output terminals of the membrane are connected to an external electrical circuit. In its normal OFF state, the diamond membrane offers

19 extremely high resistance (for example, greater than 10 Ω) and negligible electrical current flows through it.

Moreover, the present invention uses a flexible compression housing to hold the diamond membrane to allow thermal expansion and contraction of the membrane and its metal contacts, thereby avoiding mechanical stress fractures of the membrane. Further, in accordance with the present invention, the synthetic diamond is conformally grown on a conducting substrate to make the structure mechanically rigid. The synthetic diamond is then connected to the terminals of an external circuit either using compression contacts or bonded contacts. Alternatively, in accordance with another aspect of the present invention, the synthetic diamond can be conformally grown on a hybrid, insulator/conductor substrate to make the structure mechanically rigid. The synthetic diamond is then connected to the terminals of an external circuit either using compression contacts or bonded contacts.

As further discussed above, the present invention allows two or more synthetic diamond membranes to be connected electrically in series, in such a manner as to allow the series stack of membranes to hold off higher voltage than any individual member of the stack. Typically, a stack of N membranes in series should hold off N times the voltage of a single membrane switch. Alternatively, the present invention permits a back-to-back series configuration of a pair of diamond membranes, with each member of the series pair irradiated by its own electron or ultraviolet photon source. This arrangement requires the separate trigger sources (electrons or ultraviolet photons) to be in synchronism, to ensure synchronous turn-on and turn-off of both diamond switches. A further alternative embodiment in accordance with the present invention allows for an arrangement including the series stack of diamond membranes (two or more) in a common vacuum envelope, so that a common electron beam source may be used as the trigger for all the switches. Such a trigger arrangement eliminates jitter in the turn-on and turn-off of the individual switches, making them synchronous in their switching. As further described above, the present invention permits the use of a single ultraviolet light source to irradiate all the switches in series, so that the common trigger arrangement eliminates jitter in the turn-on and turn-off of the individual switches, making them synchronous in their switching.

Moreover, another aspect of the present invention permits two or more synthetic diamond membranes to be connected electrically in parallel, in such as a manner as to allow the parallel stack of membranes to conduct larger currents than any individual member of the stack. Typically, a stack of N membranes in parallel should conduct N times the current of a single membrane switch. Additionally, the parallel stack of diamond membranes (two or more) can be arranged in a common vacuum envelope, so that a common electron beam source may be used as the trigger for all the switches. Such a trigger arrangement eliminates jitter in the turn-on and turn-off of the individual switches, making them synchronous in their switching.

Furthermore, a single ultraviolet light source to irradiate all the switches in parallel is possible in accordance with the present invention, so that the common trigger arrangement eliminates jitter in the turn-on and turn-off of the individual switches, making them synchronous in their switching. Moreover, it is possible to substitute other sources of trigger energy for the above mentioned electrons or ultraviolet photon sources in all the configurations described, including other charged particles, other sources of electromagnetic radiation or other atomic and sub-atomic particles (particles or radiation).

These alternate trigger sources might even include radiation with photons of energy lower than the band-gap in synthetic diamond. Such lower energy sources would create electron-hole pairs in the diamond via multi-photon processes.

Moreover, the resistance of the synthetic diamond membrane can be controlled by controlling the energy and flux of the trigger particles (particles or radiation) so that the current supported by the diamond membrane is precisely controlled. This allows the synthetic diamond membrane to act as a high voltage, high gain, high-speed amplifier. In particular, the controlled changes to resistance of the synthetic diamond membrane can be made in response to changes in the external circuit voltage or current. This controlled change in resistance allows the synthetic diamond to act as a voltage/current regulator.

Also, as discussed above, the present invention allows the switching of the diamond membrane from its "off state to its "on" state very rapidly by rapid changes in the energy and flux of the trigger source (particles or radiation). These changes in energy and flux of the trigger source (particles or radiation) may be effected by: magnetic deflection or electric deflection for charged particles; fast shutters for sub-atomic particles or radiation. The inherent recovery time of the synthetic diamond membrane might be as short as 100 ps, allowing this type of switch to be turned on and off at repetition rates approaching 10 GHz. Also, rapid changes in the flux and energy of the incident trigger particles or radiation can be used to modify the transmission properties of the synthetic diamond membrane such that electromagnetic radiation in the radio-frequency (RF) and microwave regions of the spectrum is transmitted when the diamond is OFF but reflected when it is ON. The rapid switching of the transmission properties to RF and microwaves of the synthetic diamond membrane allows it to be used as a very fast, high power RF switch as well as a RF amplitude and phase controller. Moreover, the rapid increase in resistance of the diamond membrane when it is switched off by controlled removal of the trigger energy source can be used in an inductive energy storage power amplifier. Such a power amplifier uses a switch that offers very low resistance to flow of current during a slow, charging phase in which energy from a capacitor is used to charge an inductor, followed by a rapid, opening phase in which the diamond switch increases in resistance abruptly, causing the stored magnetic energy in the inductor to be shunted to a load that is connected in parallel with the diamond switch. The rapid changes in flux in the inductor result in a voltage developed at the switch (and the parallel load) that can be many times higher than the voltage on the primary capacitor. The inductive energy power amplifier thus takes a relatively slow, low voltage energy source from a capacitor and transforms it into a much faster, higher voltage energy source, using the conduction and opening phases of the diamond switch.

The rapid turn-off of the synthetic diamond membrane is used to operate the switch as a fast crowbar to protect other circuit elements that are in series with the switch. The rapid increase in resistance of the synthetic diamond membrane from low to high values as the trigger is switched off, stops the flow of current into the original circuit load element, thereby protecting that circuit element from catastrophic failure. Also, the rapid turn-on of the synthetic diamond membrane is used to operate the switch as a fast crowbar to protect other circuit elements that are in parallel with the switch. The rapid decrease in resistance of the synthetic diamond membrane from high to low values as it is triggered allows the current in the circuit to be diverted from the original circuit load element into the diamond switch, thereby protecting that circuit element from catastrophic failure.

Additionally, in accordance with the present invention as discussed above, the current conducted through a synthetic diamond membrane can be increased by simply increasing the conducting area of the synthetic diamond membrane. The conducting area is the area that is irradiated by the trigger source (particles or radiation). Such increase in area of a single switch provides an alternative to connecting several switches in parallel as described earlier.

As previously discussed, the use of the superior thermal properties of synthetic diamond membranes in accordance with the present invention allows the diamond switch to operate at high temperatures without reduction in the ability of the switch to hold off high voltages and switch high currents with conduction losses that are comparable to those at room temperature. Moreover, a soldering, brazing or spot welding procedure is used to form electrical contacts on the diamond so as to improve its reliability and stability when used as a detector of atomic particles or penetrating radiation above 100 keV. This soldering, brazing or spot welding procedure makes a more stable electrical contact to the diamond which in turn allows the diamond to better preserve over long duration and high accumulated doses, its substantially linear relationship between the voltage applied to the contacts and the resultant current that flows through the diamond. Additionally, a stack of discrete diamond detectors that are electrically isolated from one another can be constructed to obtain dose versus depth measurements of penetrating particles or radiation.

Moreover, the stack of diamond detectors can be used to obtain dose versus depth measurements in front of and just behind the human body during a radiation exposure and to use numerical calculations to deduce the dose versus depth delivered within the human body during radiation treatment.

Finally, in accordance with the present invention, a single diamond or a stack of diamonds can be mounted in a hermetically sealed assembly that is small and flexible enough to be inserted via a catheter into the human body allowing an in vivo measurement of dose versus depth delivered at local sites within the human body during radiation treatment.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description. Therefore, all modifications that fall within the meaning and range of equivalency of the claims in the present application are to be embraced therein.

Claims

WHAT IS CLAIMED IS:

1. A switch member, comprising: a diamond membrane having first and second surfaces; a first metallic film having a first predetermined thickness deposited on each of said first and second surfaces of said diamond membrane; a second metallic film having a second predetermined thickness deposited on said first metallic film on said first and second diamond membrane surfaces; and a third metallic film deposited on said second metallic film on said first and second diamond membrane surfaces, said third metallic film deposited on said first and second surfaces being different in thickness.

2. The switch member of claim 1 wherein said first metallic film is titanium, said second metallic film is platinum and said third metallic film is gold.

3. The switch member of claim 1 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, said third metallic film thickness on said first surface of said diamond membrane is 1,000 A, and third metallic film thickness on said second surface of said diamond membrane is 10,000 A.

4. The switch member of claim 1 further including a terminal coupled to said first surface of said diamond membrane, said terminal configured to provide electrical conduction to said diamond membrane first surface.

5. The switch member of claim 1 further including a terminal coupled to said second surface of said diamond membrane configured to provide electrical conduction to said diamond membrane second surface.

6. A switch member, comprising: a conducting substrate; a diamond membrane having a surface, said diamond membrane conformally grown on said conducting substrate configured to electrically conduct with said substrate; a first metallic film having a first predetermined thickness deposited on said diamond membrane surface; a second metallic film having a second predetermined thickness deposited on said first metallic film on said diamond membrane surface; and a third metallic film deposited on said second metallic film on said diamond membrane surface.

7. The switch member of claim 6 wherein said first metallic film is titanium, said second metallic film is platinum and said third metallic film is gold.

8. The switch member of claim 6 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, and said third metallic film thickness on said first surface of said diamond membrane is 1,000 A.

9. The switch member of claim 6 further including a plurality of terminals coupled to said diamond membrane surface and said conducting substrate, respectively, said plurality of terminals configured to provide electrical conduction to said diamond membrane.

10. A switch member, comprising: a hybrid substrate having a conducting portion; a diamond membrane a surface, said diamond membrane conformally grown on said hybrid substrate configured to electrically conduct with said conducting portion of said substrate; a first metallic film having a first predetermined thickness deposited on said diamond membrane surface; a second metallic film having a second predetermined thickness deposited on said first metallic film; and a third metallic film deposited on said second metallic film.

11. The switch member of claim 10 wherein said first metallic film is titanium, said second metallic film is platinum and said third metallic film is gold.

12. The switch member of claim 10 wherein said first predetermined thickness is 200

A, said second predetermined thickness is 200 A, and said third metallic film thickness on said first surface of said diamond membrane is 1,000 A.

13. The switch member of claim 10 further including a plurality of terminals coupled to said diamond membrane surface and said conducting portion of said hybrid substrate, respectively, said plurality of terminals configured to provide electrical conduction to said diamond membrane.

14. An apparatus for switching electrical signals, comprising: a housing including a chamber; a diamond membrane having first and second surfaces coated with a plurality of conductive elements, said membrane positioned in said chamber; a plurality of terminals coupled to said first and second surfaces of said membrane, respectively; a positioning member configured to position said membrane in said chamber, said positioning member further configured to accommodate physical displacement of said membrane; a trigger member provided at a distal position from said diamond membrane first surface configured to provide trigger source to said first surface; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further wherein said first and second surfaces of said diamond membrane selectively provides electrical conduction to said plurality of terminals in accordance with the trigger source.

15. The apparatus of claim 14 wherein said plurality of conductive elements includes: a first metallic film having a first predetermined thickness deposited on each of said first and second surfaces of said diamond membrane; a second metallic film having a second predetermined thickness deposited on said first metallic film on said first and second diamond membrane surfaces; and a third metallic film deposited on said second metallic film on said first and second diamond membrane surfaces, said third metallic film deposited on said first and second surfaces being different in thickness.

16. The apparatus of claim 15 wherein said first metallic film is titanium, said second metallic film is platinum, and said third metallic film is gold.

17. The apparatus of claim 15 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, said third metallic film thickness on said first surface of said diamond membrane is 1,000 A, and said third metallic film thickness on said second surface of said diamond membrane is 10,000 A.

18. The apparatus of claim 14 wherein said positioning member includes a spring contact configured to position said diamond membrane in said chamber by spring compression such that said diamond membrane substantially remains in said position in said chamber during thermal expansion and/or contraction of said membrane.

19. The apparatus of claim 14 wherein said trigger member includes: an electron gun having a cathode terminal coupled to said power source configured to provide electron beams; and a focusing member provided between said electron gun and said diamond membrane first surface configured to collimate said electron beams upon said diamond membrane first surface.

20. The apparatus of claim 19 wherein said focusing member includes a focusing tube positioned between said electron gun and said diamond membrane first surface, and a grid provided between said electron gun and said focusing tube.

21. The apparatus of claim 14 wherein said trigger member includes: an ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; and a focusing member provided between said ultraviolet photon gun and said diamond membrane first surface configured to collimate said photon beams onto said diamond membrane first surface.

22. The apparatus of claim 21 wherein said focusing member includes a collimating lens positioned between said photon gun and said diamond membrane first surface.

23. An apparatus for switching electrical signals, comprising: a housing including a chamber; a conducting substrate positioned in said chamber; a diamond membrane having a surface coated with a plurality of conductive elements, said membrane conformally grown on said conducting substrate wherein said membrane is configured to electrically conduct with said substrate; a plurality of terminals coupled to said diamond membrane surface and said conducting substrate, respectively; a positioning member configured to position said membrane and said substrate in said chamber, said positioning member further configured to accommodate physical displacement of said membrane; a trigger member provided at a distal position from said diamond membrane surface configured to provide trigger source to said surface; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further wherein said diamond membrane surface and said conducting substrate selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source.

24. The apparatus of claim 23 wherein said plurality of conductive elements includes: a first metallic film having a first predetermined thickness deposited on said diamond membrane surface; a second metallic film having a second predetermined thickness deposited on said first metallic film; and a third metallic film deposited on said second metallic film.

25. The apparatus of claim 24 wherein said first metallic film is titanium, said second metallic film is platinum, and said third metallic film is gold.

26. The apparatus of claim 24 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, and said third metallic film thickness on said first surface of said diamond membrane is 1,000 A.

27. The apparatus of claim 23 wherein said positioning member includes a spring contact configured to position said diamond membrane and said substrate in said chamber such that said diamond membrane substantially remains in said position in said chamber during displacement of said membrane.

28. The apparatus of claim 23 wherein said trigger member includes: an electron gun having a cathode terminal coupled to said power source configured to provide electron beams; and a focusing member provided between said electron gun and said diamond membrane surface configured to collimate said electron beams upon said diamond membrane surface.

29. The apparatus of claim 28 wherein said focusing member includes a focusing tube positioned between said electron gun and said diamond membrane surface, and a grid provided between said electron gun and said focusing tube.

30. The apparatus of claim 23 wherein said trigger member includes: an ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; and a focusing member provided between said ultraviolet photon gun and said diamond membrane surface configured to collimate said photon beams onto said diamond membrane surface.

31. The apparatus of claim 30 wherein said focusing member includes a collimating lens positioned between said photon gun and said diamond membrane surface.

32. An apparatus for switching electrical signals, comprising: a housing including a chamber; a hybrid substrate having a conducting portion positioned in said chamber; a diamond membrane having a surface coated with a plurality of conductive elements, said membrane conformally grown on said hybrid substrate wherein said membrane is configured to electrically conduct with said hybrid substrate conducting portion; a plurality of terminals coupled to said diamond membrane surface and said hybrid substrate conducting portion, respectively; a positioning member configured to position said membrane and said substrate in said chamber, said positioning member further configured to accommodate physical displacement of said membrane; a trigger member provided at a distal position from said diamond membrane surface configured to provide trigger source to said surface; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further wherein said diamond membrane surface and said hybrid substrate conducting portion selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source.

33. The apparatus of claim 32 wherein said plurality of conductive elements includes: a first metallic film having a first predetermined thickness deposited on said diamond membrane surface; a second metallic film having a second predetermined thickness deposited on said first metallic film; and a third metallic film deposited on said second metallic film.

34. The apparatus of claim 33 wherein said first metallic film is titanium, said second metallic film is platinum, and said third metallic film is gold.

35. The apparatus of claim 33 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, and said third metallic film thickness on said first surface of said diamond membrane is 1,000 A.

36. The apparatus of claim 32 wherein said positioning member includes a spring contact configured to position said diamond membrane and said substrate in said chamber such that said diamond membrane substantially remains in said position in said chamber during displacement of said membrane.

37. The apparatus of claim 32 wherein said trigger member includes: an electron gun having a cathode terminal coupled to said power source configured to provide electron beams; and a focusing member provided between said electron gun and said diamond membrane surface configured to collimate said electron beams upon said diamond membrane surface.

38. The apparatus of claim 37 wherein said focusing member includes a focusing tube positioned between said electron gun and said diamond membrane surface, and a grid provided between said electron gun and said focusing tube.

39. The apparatus of claim 32 wherein said trigger member includes: an ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; and a focusing member provided between said ultraviolet photon gun and said diamond membrane surface configured to collimate said photon beams onto said diamond membrane surface.

40. The apparatus of claim 39 wherein said focusing member includes a collimating lens positioned between said photon gun and said diamond membrane surface.

41. An apparatus for switching electrical signals, comprising: a housing including a chamber; a first diamond membrane having first and second surfaces coated with a plurality of conductive elements, said first membrane positioned in said chamber; a second diamond membrane having first and second surfaces coated with a plurality of conductive elements, said second membrane positioned in said chamber; a plurality of terminals coupled to said first and second surfaces of said first and second membranes, respectively; a plurality of grading members respectively coupled to said first and second membranes configured to provide substantially uniform electrical field across said first and second diamond membranes; a positioning member configured to position said first and second membranes in said chamber, said positioning member further configured to accommodate displacement of said membranes; a trigger portion provided at a distal position from said first surfaces of said first and second diamond membranes configured to provide a trigger source to said first surfaces; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further wherein said first and second surfaces of said first and second membranes are configured to selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source.

42. The apparatus of claim 41 wherein said plurality of conductive elements includes: a first metallic film having a first predetermined thickness deposited on each of said first and second surfaces of said first and second diamond membranes; a second metallic film having a second predetermined thickness deposited on said first metallic film on said first and second surfaces of said first and second diamond membranes; and a third metallic film deposited on said second metallic film on said first and second surfaces of said first and second diamond membranes, said third metallic film deposited on said first surfaces of said first and second diamond membranes being different in thickness than said third metallic film deposited on said second surfaces of said first and second diamond membranes.

43. The apparatus of claim 42 wherein said first metallic film is titanium, said second metallic film is platinum, and said third metallic film is gold.

44. The apparatus of claim 42 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, said third metallic film thickness on said first and second diamond membranes first surface is 1,000 A, and said third metallic film thickness on said first and second diamond membranes second surface is 10,000 A.

45. The apparatus of claim 41 wherein said positioning member includes a plurality of spring contacts configured to position said first and second diamond membranes in said chamber such that said diamond membranes is provided in a substantially constant position in said chamber during displacement of said membranes.

46. The apparatus of claim 41 wherein each of said plurality of grading members includes: a metal grading portion coupled to said respective membrane; and a passive divider network coupled to said metal grading ring configured to lower signals on said metal grading ring by approximately 50%.

47. The apparatus of claim 41 wherein said trigger portion includes: an electron gun having a cathode terminal coupled to said power source configured to provide electron beams; and a focusing member provided between said electron gun and said first and second diamond membrane first surfaces configured to collimate said electron beams upon said first and second diamond membrane first surfaces.

48. The apparatus of claim 47 wherein said focusing member includes a focusing tube positioned between said electron gun and said diamond membrane first surfaces, and a grid provided between said electron gun and said focusing tube.

49. The apparatus of claim 41 wherein said trigger portion includes: an ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams to said first and second diamond membrane first surfaces; and a focusing member provided between said ultraviolet photon gun and said first and second diamond membrane first surfaces configured to collimate said photon beams onto said first and second diamond membrane first surfaces.

50. The apparatus of claim 49 wherein said focusing member includes a collimating lens positioned between said photon gun and said first and second diamond membrane first surfaces.

51. The apparatus of claim 41 wherein said trigger portion includes: a first electron gun having a first cathode terminal coupled to said power source configured to provide electron beams to said first diamond membrane first surface; a second electron gun having a second cathode terminal coupled to said power source configured to provide electron beams to said second diamond membrane first surface; a first focusing member provided between said first electron gun and said first diamond membrane first surface configured to collimate said electron beams upon said first diamond membrane first surface; and a second focusing member provided between said second electron gun and said second diamond membrane first surface configured to collimate said electron beams upon said second diamond membrane first surface.

52. The apparatus of claim 51 wherein each of said first and second focusing members includes a focusing tube positioned between said respective electron gun and said diamond membrane first surfaces, and a plurality of grids provided between said respective electron guns and said respective focusing tubes.

53. The apparatus of claim 41 wherein said trigger portion includes: a first ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams to said first diamond membrane first surface; a second ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams to said second diamond membrane first surface; a first focusing member provided between said first ultraviolet photon gun and said first diamond membrane first surface configured to collimate said photon beams onto said first diamond membrane first surface; and a second focusing member provided between said second ultraviolet photon gun and said second diamond membrane first surface configured to collimate said photon beams onto said second diamond membrane first surface.

54. The apparatus of claim 53 wherein each of said first and second focusing members includes a collimating lens positioned between said respective photon gun and said diamond membranes first surface.

55. The apparatus of claim 41 further including a conducting member having first and second surfaces, wherein said first membrane second surface and second membrane second surface are coupled to said conducting member first and second surfaces, respectively.

56. The apparatus of claim 41 wherein said terminal connected to said first membrane second surface is coupled to said terminal connected to said second membrane first surface.

57. The apparatus of claim 41 wherein said terminal coupled to said first membrane first surface is connected to said terminal coupled to said second membrane first surface, and further, wherein said terminal coupled to said first membrane second surface is connected to said terminal coupled to said second membrane second surface.

58. The apparatus of claim 57 wherein said grading members are coupled to each other.

59. An apparatus for switching electrical signals, comprising: a housing including a chamber; a first conducting substrate positioned in said chamber; a first diamond membrane having a surface coated with a plurality of conductive elements, said first membrane conformally grown on said first conducting substrate wherein said first membrane is configured to electrically conduct with said first substrate; a second conducting substrate positioned in said chamber; a second diamond membrane having a surface coated with a plurality of conductive elements, said second membrane conformally grown on said second conducting substrate wherein said second membrane is configured to electrically conduct with said second substrate; a plurality of terminals coupled to said first and second membrane surfaces and said first and second substrates; a plurality of grading members respectively coupled to said first and second membranes configured to provide substantially uniform electrical field across said first and second membranes; a positioning member configured to position said first and second membranes in said chamber, said positioning member further configured to accommodate displacement of said membranes; a trigger portion provided at a distal position from said surfaces of said first and second diamond membranes configured to provide a trigger source to said surfaces; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further wherein said first and second membrane surface and said first and second substrates are configured to selectively provide electrical conduction to said plurality of terminals in accordance with the trigger source.

60. The apparatus of claim 59 wherein said plurality of conductive elements includes: a first metallic film having a first predetermined thickness deposited on each of said first and second diamond membrane surfaces; a second metallic film having a second predetermined thickness deposited on said first metallic film on each of said first and second diamond membrane surfaces; and a third metallic film deposited on said second metallic film on each of said first and second diamond membrane surfaces.

61. The apparatus of claim 60 wherein said first metallic film is titanium, said second metallic film is platinum, and said third metallic film is gold.

62. The apparatus of claim 60 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, and said third predetermined thickness is 1,000

A.

63. The apparatus of claim 59 wherein said positioning member includes a plurality of spring contacts configured to position said first and second diamond membranes in said chamber such that said diamond membranes is provided in a substantially constant position in said chamber during displacement of said membranes.

64. The apparatus of claim 59 wherein each of said plurality of grading members includes: a metal grading portion coupled to said respective membrane; and a passive divider network coupled to said metal grading ring configured to lower signals on said metal grading ring by approximately 50%.

65. The apparatus of claim 59 wherein said trigger portion includes: an electron gun having a cathode terminal coupled to said power source configured to provide electron beams; and a focusing member provided between said electron gun and said first and second diamond membrane surfaces configured to collimate said electron beams on said first and second diamond membrane surfaces.

66. The apparatus of claim 65 wherein said focusing member includes a focusing tube positioned between said electron gun and said diamond membrane surfaces, and a grid provided between said electron gun and said focusing tube.

67. The apparatus of claim 59 wherein said trigger portion includes: an ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; and a focusing member provided between said ultraviolet photon gun and said first and second diamond membrane surfaces configured to collimate said photon beams onto said first and second diamond membrane surfaces.

68. The apparatus of claim 67 wherein said focusing member includes a collimating lens positioned between said photon gun and said first and second diamond membrane surfaces.

69. The apparatus of claim 59 wherein said trigger portion includes: a first electron gun having a first cathode terminal coupled to said power source configured to provide electron beams; a second electron gun having a second cathode terminal coupled to said power source configured to provide electron beams; a first focusing member provided between said first electron gun and said first diamond membrane surface configured to collimate said electron beams on said first diamond membrane surface; and a second focusing member provided between said second electron gun and said second diamond membrane surface configured to collimate said electron beams on said second diamond membrane surface.

70. The apparatus of claim 69 wherein each of said first and second focusing members includes a focusing tube positioned between said respective electron gun and said diamond membrane surfaces, and a plurality of grids provided between said respective electron guns and said respective focusing tubes. e.

71. The apparatus of claim 59 wherein said trigger portion includes: a first ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; a second ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; a first focusing member provided between said first ultraviolet photon gun and said first diamond membrane surface configured to collimate said photon beams onto said first diamond membrane surface; and a second focusing member provided between said second ultraviolet photon gun and said second diamond membrane surface configured to collimate said photon beams onto said second diamond membrane surface.

72. The apparatus of claim 71 wherein each of said first and second focusing members includes a collimating lens positioned between said respective photon gun and said diamond membrane surfaces.

73. The apparatus of claim 59 further including a conducting member having first and second surfaces, wherein said first and second conducting substrates are coupled to said conducting member first and second surfaces, respectively.

74. The apparatus of claim 59 wherein said terminal connected to said first conducting substrate is coupled to said terminal connected to said second membrane surface.

75. The apparatus of claim 59 wherein said terminal coupled to said first membrane surface is connected to said terminal coupled to said second membrane surface, and further, wherein said terminal coupled to said first conducting substrate is connected to said terminal coupled to said second conducting substrate.

76. The apparatus of claim 75 wherein said grading members are coupled to each other.

77. An apparatus for switching electrical signals, comprising: a housing including a chamber; a first hybrid substrate having a conducting portion positioned in said chamber; a first diamond membrane having a surface coated with a plurality of conductive elements, said first membrane conformally grown on said first hybrid substrate wherein said first membrane is configured to electrically conduct with said first substrate conducting portion; a second hybrid substrate having a conducting portion positioned in said chamber; a second diamond membrane having a surface coated with a plurality of conductive elements, said second membrane conformally grown on said second hybrid substrate wherein said second membrane is configured to electrically conduct with said second substrate conducting portion; a plurality of terminals coupled to said first and second membrane surfaces, and said first and second substrate conducting portions; a plurality of grading members respectively coupled to said first and second membranes configured to provide substantially uniform electrical field across said first and second membranes; a positioning member configured to position said first and second membranes in said chamber, said positioning member further configured to accommodate displacement of said membranes; a trigger portion provided at a distal position from said first and second diamond membrane surfaces configured to provide a trigger source to said surfaces; and a power supply coupled to said trigger member configured to provide signal pulses to said trigger member; wherein said chamber is substantially vacuum, and further wherein said first and second membrane surfaces and said conducting portions of said first and second substrates are configured to selectively provide electrical conduction to said plurality of terminals in accordance with said trigger source.

78. The apparatus of claim 77 wherein said plurality of conductive elements includes: a first metallic film having a first predetermined thickness deposited on each of said first and second diamond membrane surfaces; a second metallic film having a second predetermined thickness deposited on said first metallic film on each of said first and second diamond membrane surfaces; and a third metallic film deposited on said second metallic film on each of said first and second diamond membrane surfaces.

79. The apparatus of claim 78 wherein said first metallic film is titanium, said second metallic film is platinum, and said third metallic film is gold.

80. The apparatus of claim 78 wherein said first predetermined thickness is 200 A, said second predetermined thickness is 200 A, and said third metallic film thickness is 1,000 A.

81. The apparatus of claim 77 wherein said positioning member includes a plurality of spring contacts configured to position said first and second diamond membranes in said chamber such that said diamond membranes are provided in a substantially constant position in said chamber during displacement of said membranes.

82. The apparatus of claim 77 wherein each of said plurality of grading members includes: a metal grading portion coupled to said respective membrane; and a passive divider network coupled to said metal grading ring configured to lower signals on said metal grading ring by approximately 50%.

83. The apparatus of claim 77 wherein said trigger portion includes: an electron gun having a cathode terminal coupled to said power source configured to provide electron beams; and a focusing member provided between said electron gun and said first and second diamond membrane surfaces configured to collimate said electron beams on said first and second diamond membrane surfaces.

84. The apparatus of claim 83 wherein said focusing member includes a focusing tube positioned between said electron gun and said diamond membrane surfaces, and a grid provided between said electron gun and said focusing tube.

85. The apparatus of claim 77 wherein said trigger portion includes: an ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; and a focusing member provided between said ultraviolet photon gun and said first and second diamond membrane surfaces configured to collimate said photon beams onto said first and second diamond membrane surfaces.

86. The apparatus of claim 85 wherein said focusing member includes a collimating lens positioned between said photon gun and said first and second diamond membrane surfaces.

87. The apparatus of claim 77 wherein said trigger portion includes: a first electron gun having a first cathode terminal coupled to said power source configured to provide electron beams; a second electron gun having a second cathode terminal coupled to said power source configured to provide electron beams; a first focusing member provided between said first electron gun and said first diamond membrane surface configured to collimate said electron beams on said first diamond membrane surface; and a second focusing member provided between said second electron gun and said second diamond membrane surface configured to collimate said electron beams on said second diamond membrane surface.

88. The apparatus of claim 87 wherein each of said first and second focusing members includes a focusing tube positioned between said respective electron gun and said diamond membrane surfaces, and a plurality of grids provided between said respective electron guns and said respective focusing tubes.

89. The apparatus of claim 77 wherein said trigger portion includes: a first ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; a second ultraviolet photon gun coupled to said power source configured to provide ultraviolet photon beams; a first focusing member provided between said first ultraviolet photon gun and said first diamond membrane surface configured to collimate said photon beams onto said first diamond membrane surface; and a second focusing member provided between said second ultraviolet photon gun and said second diamond membrane surface configured to collimate said photon beams onto said second diamond membrane surface.

90. The apparatus of claim 89 wherein each of said first and second focusing members includes a collimating lens positioned between said respective photon gun and said diamond membrane surfaces.

91. The apparatus of claim 77 further including a conducting member having first and second surfaces, wherein said first and second hybrid substrates are coupled to said first and second surfaces of said conducting member, respectively.

92. The apparatus of claim 77 wherein said terminal connected to said first hybrid substrate is coupled to said terminal connected to said second membrane surface.

93. The apparatus of claim 77 wherein said terminal coupled to said first membrane surface is connected to said terminal coupled to said second membrane surface, and further, wherein said terminal coupled to said first hybrid substrate is connected to said terminal coupled to said second hybrid substrate.

94. The apparatus of claim 93 wherein said grading members are coupled to each other.