US3593045A

US3593045A - Multiaddress switch using a confined electron beam in a semiconductor

Info

Publication number: US3593045A
Application number: US888331A
Authority: US
Inventors: Dirk J Bartelink; George Persky
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1969-12-29
Filing date: 1969-12-29
Publication date: 1971-07-13
Anticipated expiration: 1988-07-13

Abstract

This invention involves a solid state charge carrier beam deflection apparatus (solid-state equivalent of a cathode-ray tube), utilizing a high resistivity semiconductor body for the propagation medium of the beam. A relatively high electric field in the semiconductory body is utilized to propel a beam of electrons or holes in a direction from a rear surface to a front surface of the body, the beam being characterized by a confined cross section throughout the beam''s trajectory. Deflection of the beam in the body can be accomplished by transverse electric or magnetic field; detection of the beam can be accomplished by a variety of means, including ohmic contacts and Schottky barrier diodes located at the front surface of the semiconductor body.

Description

United States Patent Dirk .1. Bartelinlt Morris Township, Morrls County;

George Persky. North Planfleld, both of, NJ.

Dec. 29. 1969 July 13, 197! Bell Telephone Laboratories, Incorporated Murray Hill, Berkeley Heights, NJ.

Inventors Appl. No. Filed Patented Assignee Referencs Cited UNITED STATES PATENTS 4/1957 Shockley 307/299 2.820154 1/1958 Kurshan v 307/299 2,916,639 12/1959 Krembs t. 307/299 2,967,952 1/1961 Shockley i 4 307/299 2.922398 1/1960 Henisch 307/303 Primary Examiner-- Donald D. Forrer Assistant Examiner-Harold A. Dixon Attorneys-R4 J. Guenther and Arthur J. Torsiglieri ABSTRACT: This invention involves a solid state charge carrier beam deflection apparatus (solid-state equivalent of a cathode-ray tube), utilizing a high resistivity semiconductor body for the propagation medium of the beam. A relatively high electric field in the semiconductory body is utilized to propel a beam of electrons or holes in a direction from a rear surface to a front surface of the body, the beam being characterized by a confined cross section throughout the beams trajectory. Deflection of the beam in the body can be accomplished by transverse electric or magnetic field; detection of the beam can be accomplished by a variety of means, including ohmic contacts and Schottky barrier diodes located at the front surface of the semiconductor body.

VOLTAGE DETECTOR VOLTAGE 3 DETECTQR ass VOLTAGE DETECTOR. 25.3

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FIG. 2.2

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2 3 1M 7. 0 W w LN. R x I a. M m m m x 0 T w m 7 2 x .0 w M N J 2 N/ a PATENTEU JUL 1 319?:

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PATENTEU JUL 1 3187! SHEET U [1F 4 DETECTOR VOLTAGE MULTIADDRESS SWITCH USING A CONFINED ELECTRON BEAM IN A SEMICONDUCTOR FIELD OF THE INVENTION This invention relates to the field of solid-state semiconductor apparatus, in particular to charge carrier beam deflection apparatus in which a beam of charge carriers in a semiconductor body is deflected by means of transverse electric or magnetic field applied to the body.

BACKGROUND OF THE INVENTION A multiaddress electronic switch apparatus is useful in many applications. Apparatus in which a beam of charge carriers can be deflected in a semiconductor body has a variety of applications. These include a multiaddress electronic switch, of which a camera tube is a specific example.

Other types of multiaddress switches, such as transistor cir' cuits, are rather complicated, relatively bulky, and not easily adapted to use as a camera device.

US. Pat. Nos. 2,790,037 issued on Apr. 23, 1957 to W. Shockley, and 2,553,490 issued on May 15, I951 to R. L. Wallace, lr., involve solid-state semiconductor devices in which the lateral displacement of the flow of charge carriers in a semiconductor body is controlled by applied electric or magnetic fields, thereby furnishing some degree of switching function. However, the flow ofcharge carriers in these devices suffers from a relatively large amount of background noise and lateral spreading of the flow of charged carriers, thereby making difficult the fabrication of multiaddress type of switching devices. It would therefore be desirable to have a device in which both background noise and lateral beam spreading are minimized.

SUMMARY OF THE INVENTION In this invention. a charge carrier beam of confined cross section is propagated from a rear major surface to a front major surface of a zone of relatively high resistivity (to be denoted by "intrinsic or l-type conductivity) in a solid semiconductor single crystal body, such as silicon. By a charge carrier beam is means a beam of electrons (or holes) in the semiconductor. Such a charge carrier beam can be injected in the intrinsic zone by the emission of charge carriers from a forward biased P-N junction of confined cross section, or by the emission of charge carriers in the intrinsic zone in response to a beam of light (photoexcitation) of confined cross section. Provided a suitably large bias voltage is applied across the semiconductor, the charge carrier beam propagates through the semiconductor across the intrinsic zone with a confined cross section, i.e., without substantial spreading outwards or lateral diffusion. This voltage is selected in the optimal case such that the lateral diffusion over the time of transit is a minimum. However, too high a bias voltage can produce a longitudinal electric field which tends to increase the lateral beam spread, because of an increased diffusion coefficient without a compensating decrease in the transit time (due to velocity saturation). By the longitudinal electric field is meant the electric field in the direction of propagation of the beam. On the other hand, too low a longitudinal electric field tends also to increase the lateral beam spread because of an increased transit time without a compensating decrease in diffusion coefficient. Therefore, advantageously, the longitudinal electric field is selected in the optimal case to make the average quotient of diffusion constant and velocity a minimum, i.e., i. eraged in space over path of the beam in the l-zone of the semiconductor body. In any event, it is important that the longitudinal electric field should be sufficient to deplete the semiconductor of substantially all of its mobile charges due to impurities. Thereby, background noise is reduced by reason of this depletion of mobile charges.

Typically, 200 volts across the I-zone in a silicon semiconductor body I microns thick is used for the purpose of providing suitable bias voltage, in order to produce the desired electric field in the semiconductor. Moreover, this bias volt age produces an electric field in the semiconductor such that, at all points of the charge carrier beam, the charge carriers in the beam substantially follow the direction of the electric field in the body. Thus, the direction of propagation of the beam is everywhere substantially parallel to the electric field in the body. Moreover, deflection of the beam is obtained by means of auxiliary electric or magnetic fields applied to the semiconductor body at right angles (transverse) to the direction of propagation of the beam of charge carriers. Thereby a resultant electric field is produced in the l-zone, and the trajectory of the beam of charge carrier follows the direction of this resultant field.

In order to obtain the sufficiently high electric field in the I- zone mentioned above, while maintaining relatively low charge beam currents to prevent space charge, the rear surface of the I-zone advantageously is covered with a layer of semiconductor having a conductivity which is of a type in which the charge carriers in the charge carrier beam are minority carriers, and having a conductivity which is of a type in which the charge carriers in the charge carrier beam are minority carriers, and having a conductivity which is at least an order of magnitude higher than that of the l-zone itself. This layer provides an electrical rectifying barrier against injection of an unduly large number of charge carriers in the 1- zone in the region thereof where there is no charge carrier beam. Thereby, the charge carrier beam can be formed with a confined cross section and with a controllably low current density.

Beam spreading due to space charge formation is prevented by maintaining the current in the charge carrier beam at rather low values even in the presence of the longitudinal electric field. This current is maintained typically at about 0.1 microamperes for a beam with a diameter of about 5 microns. In addition, the layer of semiconductor, which produces the rectifying barrier at the rear surface of the l-zone, advantageously provides a substantially equipotential surface thereat. As an alternative, a layer of metal which forms a Schottky barrier with the I-zone can be used to cover the rear surface of the l-zone for these purposes of providing the equipotential surface thereat and the rectifying barrier.

Preferably, the l-zone is not compensated material, that is, the relatively high resistivity of the l-zone is attributable to relatively high purity rather than equal (compensated) numbers of donor and acceptor impurities; thereby, lateral diffusion of the charge carrier beam is minimized.

In a specific embodiment of this invention, a silicon semiconductor body with a N"P*lN conductivity type zone structure (typically formed by impurity diffusion, ion implantation, and/or epitaxy) is utilized as the solid-state body in which deflection of a charge carrier beam, specifically an electron beam, takes place. By the symbol N or l is meant strongly (highly conductive) respectively P-type or Ntype semiconductor; by the symbol l is meant relatively high resistivity material but which can be very weakly N-type or P- type, and by the symbol N is meant moderately (moderately conductive) N-type semiconductor. It should be understood that the symbol N (or F") denotes a semiconductor zone having at least an order of magnitude higher conductivity than a zone denoted by the symbol N (or P), that the symbol N (or P) denotes a semiconductor zone having at least an order of magnitude higher conductivity than a zone denoted by the symbol l. The N-zone advantageously has a relatively small cross section area as compared with that of the P"-zone; whereas the P*-zone is contiguous with the l-zone over a major geometrical boundary surface thereof. Together with a small area metal contact to the small area N -zone, this N*-zone serves as an injecting contact of the electron beam at the rear surface of the semiconductor body. The electrons in the beam are introduced into the l-zone of the semiconductor by reason of the phenomenon of injection, in response to a forward voltage bias applied to the N*-zone relative to the P"-zone through the metal contact to the N*-zone. The P -zone is sufficiently thin (less than a diffusion length therein of the injected minority carrier electrons) so that the injected electrons which pass through the P -Zone enter the l-zone with essentially the same confined cross section as the cross section area of the injecting N -zone.

An applied "reverse" voltage bias with respect to the remaining PIN portion of the structure produces an electric field in the l-zone which propels the electrons in the beam from the P-zone (in which the electrons are minority carriers) through the l-zone into the N-zone (in which the electrons are majority carriers) at the front surface of the semiconductor body. These electrons arrive in the N-zone in a beam with essentially the same cross section as that of the N injecting zone itself, provided the electric field parallel to the propagation ofthe beam (longitudinal field") in the l-zone is properly selected. Advantageously this electric field is in the range of about 0.5Xl to l0 l0 volt/cm, typically 2X10 volt/cm, in silicon. in order to keep this electric field within the desired range in the T-zone, the impurity concentration in this lzone should be sufficiently low in order to maintain this uniformity of the electric field, and thereby prevent it from going outside the desired range, as is predictable by Poisson's equation. Advantageously, the interface or junction of the P*- zone with the l-zone and the interface or junction of the N- zone with the l-zone are mutually parallel planar surfaces excepting for the edges, thereby providing a pair of parallel and substantially equipotential surfaces. This geometry further promotes a uniform electric field in the l-zone, similar to the case ofthe conventional parallel plate capacitor. Whereas the P*-zone provides a rectifying barrier against the injection of electrons at the rear of the I-zone (except underneath the N injecting zone), the N-zone provides a rectifying barrier against injection of holes at the front of the l-zone. Thus, background noise is minimized.

Transverse deflection of the electron beam in the l-zone is accomplished by means ofa transverse electric field signal applied therein, that is, perpendicular to the direction of propagation of the beam. This transverse field is set up by means of an auxiliary deflection voltage source connected to a pair of electrodes on the sidewalls of the semiconductor body. Detection of the position of incidence of the electron beam at the front surface of the body is accomplished by means of an array ofmetal ohmic electrodes located on the front surface of the semiconductor body, each electrode being connected to a voltage detector for sensing the voltage produced by the incidence of the beam at a particular position on this front surface.

Beam widths ofthe order of 5 microns with no more than an added 5 microns lateral spreading, can be propagated in this invention through an l-zone in silicon of I00 microns in thickness, provided the electric field which propels the beam is properly selected in accordance with the above-mentioned criteria. Moreover, the current density in the charge carrier beam advantageously should be kept below 0.5 microarnpere, typically at 0.1 microampere, for a beam cross section diameter of the order of 5 microns, in order to prevent the formation ofa space charge in an amount which would otherwise cause undesired beam spreading.

With the confined beams of charge carriers in this invention, an analogue representation of input electric or magnetic signals applied to the body can be obtained at the front surface of the body, in the form of the information as to the position of impact of the beam thereat as a function of time. Moreover, in an alternate embodiment, this invention can be used as a solidstate camera tube in which a geometrical pattern of optical input radiation (the picture) can be converted into an electrical output signal whose variation with time is an analogue representation of the geometrical pattern in the picture. This is achieved by the injection into the body of confined beams of charge carriers by the optical input (photoexcitation") and deflection of the charge carrier beams according to conventional horizontal and vertical electrical scanning signals. The

detection of the beams at the front surface of the body provides the analogue output signal corresponding to the picture.

BRIEF DESCRIPTION OF THE DRAWING This invention together with its objects, features, and advantages can be better understood from the following detailed description when read in conjunction with the drawing (not to scale for the sake of clarity) in which:

FIG. I is a perspective view partly in cross section, of a solid-state charge carrier beam deflection apparatus with passive type of detection, according to a specific embodiment of the invention;

FIG. 2 is a perspective view, partly in cross section, of a solid-state electronic camera apparatus, according to another specific embodiment of the invention;

FIG. 2.] is a perspective view, partly in cross section, of a portion of the solid'state electronic camera shown in FIG. 2, showing alternative means for beam detection;

FIG. 2.2 is a top view, in cross section, of the solid-state electronic camera shown in FIG. 2, but including an electrical Schottky barrier;

FIG. 3 is a perspective view, partly in cross section, of a solid-state charge carrier beam deflection apparatus, with active type of detection, according to another specific embodiment ofthe invention;

FIG. 3.1 is a perspective view, partly in cross section, of a portion of the solid-state charge carrier beam deflection apparatus shown in FIG. 3, showing alternative means for the beam detection;

FIG. 3.2 is a perspective view, partly in cross section, of a portion of the solid-state charge carrier beam deflection apparatus shown in FIG. 3, with another alternative means for the beam detection; and

FIG. 4 is a perspective view, partly in cross section, of a solid-state charge carrier beam deflection apparatus with both horizontal and vertical deflection control, according to yet another specific embodiment of the invention.

DETAILED DESCRIPTION In FIG. 1, a solid-state electronic deflection apparatus is shown in accordance with a specific embodiment of the invention. An electron beam ll, whose cross section is of confined extent in a solid silicon semiconductor body 12 of a rectangular parallelepiped shape, propagates through the semiconductor body 12 in a direction from a rear surface l3 to a front surface l4 thereof. The silicon semiconductor body 12, preferably a single crystal, includes large area zones l5, l6, and 17 of P", l, N-type conductivity, respectively. Typically, the semiconductor crystal body 12 is oriented (111). Here the symbol P", referring to zone l5, represents strongly'P-type conductivity silicon semiconductor; that is, containing a net significant acceptor impurity concentration of the order of It) per cm. or more. The symbol l referring to zone l6 represents either intrinsic or nearly intrinsic type conductivity silicon semiconductor, that is, containing a net significant impurity concentration of either donors or acceptors, preferably acceptors, of the order of IO per cm. or less (corresponding to a bulk resistivity of the order of lOKQ-cm. or more). The symbol N referring to zone 17 represents moderately N-type conductivity; that is, containing a net significant impurity concentration of donors in the range between l0 and 10" per cm., typically 10" per emf. The zones 15 and I! are relatively thin, of the order of one micron in the x direction; whereas the region 16 is relatively thick, of the order of I00 microns in the x direction. An injecting zone 15.] of N*-type conductivity, located at a portion of the rear surface 13, forms a P-N junction at its boundary with the P*-zone l5; and this N -zone 15.] acts as a source of electrons for the electron beam 11.

Voltage is applied by the battery 21, typically about 2 volts, to a metal contact 15.2, typically aluminum or platinum. The contact 15.2 has a cross section at the rear surface 13 which is in the Nand coincident with the injecting zone 15.1.

A rectangular zone 18 of N -type conductivity is located in the Nttype zone 17, at the front surface 14 of the body 12, in order to furnish a collecting terminal for the beam 11. Typically, both the N*zones 15.1 and 18 are diffused regions approximately 0.2 micron deep, having a net significant impurity concentration of the order of per cm. or more.

A wire lead 19 electrically connects the positive terminal of a battery 20 to the N*-zone 18 through an ohmic contact 18.]. A wire lead 19.1 electrically connects common terminal 20.5 (between the positive terminal of the battery 21 and the negative terminal of the battery 20) to the P -zone through an ohmic contact 19.2, in order to provide a sufficient electric field for propagating the beam 11 in the l-zone 16. Advantageously, the injecting zone 15.1 under the contact 15.2 has a diameter of the order of 5 micron or less, so that the electron beam 11 at the front surface 14 also has a confined cross section with approximately the same diameter.

The polarity of the battery is arranged as shown in FIG. 1 to furnish a reverse bias to the P INN" conductivity type structure formed by

zones

15, 16, 17, and 18; whereas the polarity of the battery 21 is arranged to furnish a forward bias to the N injecting zone 15.1 relative to the P -zone 15. Thereby, the battery 20 sets up the desired relatively high electric field in the lzone 16 in the x direction, in order to order to propagate the electron beam 11 with minimal diffu sion, as described more particularly below; while the battery 21 causes the injection of the electron beam 11 into this l-zone 16. Advantageously, the interfaces of

zones

15 and 17 with zone 16 are m the form of mutually parallel planes; so that the electric field in the x direction is uniform in the l-zone 16,just as the uniform electric field in a parallel plate condenser. it should be understood that the uniformity of this electric field may be slightly perturbed by the beam 11 especially in the presence of transverse deflecting fields.

In order to have a means for deflecting the beam 11 in the transverse y direction, a pair of

metal electrode plates

22 and 23 are located on opposite sidewall surfaces of the body 12, but separated and insulated electrically therefrom by dielectric insulating layers 22.5 and 23.5, respectively. The linear sawtooth electrical signal source 24, electrically connected to the pair of

metal plates

22 and 23, sets up a deflecting electric field in the body 12 having a component in the y direction perpendicular (transverse) to the x direction. Thereby, the beam 1 1 sweeps the front surface 14 substantially linearly in time.

In order to propel the electrons in the beam 11 from the rear surface 13 to the front surface 14, the voltage supplied by the battery 20 to zones 18 and 15.2 is in the range of about 40 to 400 volts, typically about 200 volts; so that the electric field in the region 16 in the silicon body 12 is typically about 20 kvJcm. In any event, the electric field should be below the value at which breakdown occurs in the silicon body 12, and above the value required to deplete zone 16 ofsubstantially all its mobile charges. With this value of electric field, the diameter of the cross section of the electron beam 11 at the position of impact at the front surface 14 typically is no more than approximately 5 microns greater than the diameter thereof at the rear surface 13. Thereby, the electron beam 11 propagates as a relatively confined beam from the rear surface 13 to the front surface 14.

It should be understood that, in order to have a relatively confined beam of charge carriers, the cross section dimensions in the yz plane of the injecting zones 15.1 is at least an order of magnitude less than any of the cross section dimen sions of the front surface 14 of the body 12. Typically, the diameter of the injecting zone 15.] (and hence of the beam 11) in the y: plane is in the range of about one to 5 microns. whereas the linear dimensions in the and z direction of both the front surface 14 and the rear surface 13 are of the order of about 500 microns or more.

The location of the impact on the front surface 14 of the electron beam 11 is controlled by means of the instantaneous electric field in the y direction caused by the voltage supplied by the linear sawtooth signal source 24. It should be understood that the voltage supplied by the signal source 24 provides only horizontal control (in the y direction) of this location of impact, and that an additional separate signal source in combination with insulated metal electrodes (not shown) on the top and bottom surfaces of the body 12 can provide vertical control (in the z direction) of this location of impact if desired.

The location of impact of the electron beam 11 on the front surface 14 can be detected by a variety of means, as illustrated in FIG. 1. For example, evaporated metal strip electrodes 25.1 and 25.2 on the front surface 14, in combination with a volt age detector 25.3 electrically connected to these electrodes, can be used for the purpose of this detection. Directly underneath each of the electrodes 25.1 and 25.2 is located an 0.2 micron deep diffused region (not shown) of N -type semiconductor, in order to afford ohmic contact between these electrodes and the N zone 17, as should be understood by one skilled in the art. Each of the electrodes 25.1 and 25.2 is of the order of 5 microns or leas in width, typically 2 microns; and the electrodes 25.1 and 25.2 are separated from each other as well as from any other electrodes by a distance likewise of the order of 5 microns; that is, approximately the diameter of the electron beam 11 at the front surface 14.

When the electron beam 11 strikes the front surface 14 to the right-hand side of the electrode 25.2, then there will be a voltage drop between the electrode 25.2 and 25.1 sensed by the detector 25.3; and when the beam 11 strikes to the lefthand side of the electrodes 25.1, there will be no such voltage drop sensed by the detector 25.3. This voltage drop between the electrodes 25.1 and 25.2 is due to the electric field set up between the N collecting zone 18 and location of impact of the beam 11 on the front surface 14. This in turn is caused by the electric charge accumulation built up on the right-hand side of the electrode 25.2 at the surface 14 when the current due to the beam 11 experiences the electrical resistance of zone 17. Of course, if the beam 11 strikes on the left-hand side of the electrode 25.1, then no voltage drop is produced between the electrodes 25.1 and 25.2. Finally, if the beam 11 strikes the surface 14 at a location which lies between or overlaps the electrodes 25.1 and 25.2, then intermediate values of voltage will be sensed by the detector 25.3 depending upon the exact distribution of the locations of impact of various cross-sectional portions of the beam 11.

The configuration of another set of metal electrodes 26.1 and 26.2, shown in FIG. 1, is useful for detecting whether the location of the impact of the electron beam 11 is within or without the U-shaped region encompassed by the outside electrode 26.1. When this location of impact is within this U- shaped region, there will be a voltage drop sensed by the detector 26.3; and when this location is outside this U-shaped region, no such voltage drop will be sensed by the detector 26.3. Except for their geometric configurations, the electrodes 26.1 and 26.2 are similar to the electrodes 25.1 and 25.2.

The configurations just described of electrodes exemplified by 25.1 with 25.2, and 26.1 with 26.2, are useful for onedimensional (horizontal) detection of the location of impact of the beam 11 at the front surface 14. Two-dimensional (horizontal and vertical) detection can be furnished by the configuration illustrated by a central ohmic contact electrode 27.2 in combination with both a ring ohmic contact electrode 27.1 surrounding this central electrode 27.2, and a voltage detector 27.3. In this case, a voltage is sensed by the detector 27.3 only when the electron beam strikes the surface 14 at a location inside the ring electrode 27.1. For a typical resolution in the detection process, the central electrode 27.2 has a diameter equal to or less than one-half the diameter of the cross section of the electron beam 11, while the inside diameter of the ring electrode 27.1 advantageously is approximately equal to this diameter of the beam 11. Again, it should be mentioned that directly underneath each of the metal electrodes 27.1 and 27.2 there is an 0.2 micron deep diffused region of N -type conductivity, in order to afford ohmic contact between these electrodes and the N zone 17, as should be understood by a skilled worker.

It should be noted that the electrodes 25.1, 25.2, 26.1, 26.2, 27.1, and 27.2, typically aluminum or platinum, can be deposited selectively upon the surface 14 of the semiconductor body 12 by well-known vapor deposition methods upon the front surface 14 of the body 12. Moreover, the

zones

15 and 17 typically are formed by well-known methods of diffusion or ion implantation into, or epitaxial growth upon, the 1' region 16 serving as a substrate therefor. Finally, an array of any of the pairs of detector electrodes 25.1, 25.2, or 26.1, 26.2, or 27.1, 27.2, can be disposed on the front surface 14 for multiple detection of the various positions of the beam 11 thereat.

FIG. 2 shows a solid-state electronic camera apparatus in accordance with another embodiment of the invention. In many respects, there are close similarities between this em' bodiment and the one shown in H6. 1; therefore, the same reference numerals are used to designate the elements common to these embodiments. The main difference between the embodiments shown in FIGS. 1 and 2 lies in the means for producing the electron beam.

As shown in Fl(]. 2, an optical source 15.5 supplies a pattern of optical radiation in the form of beams of light 15.6. The geometrical pattern of the beams 15.6 is ultimately to be detected or recorded by means of the detector 27.3. The beams of light 15.6 are incident upon the rear surface 13 of the body 12 of the same material and geometry specified above in the discussion of the apparatus shown in F10. I.

it is important that the optical radiation from the source 155 penetrate through the P*-zone 15 into the l-zone 16, so that the electron beams 11 are produced in the body 12 by reason of the phenomenon of photoexcitation of electrons in accordance with the pattern of light in the beams 15.6. If the optical radiation in the beams 15.6 lies in the visible portion of the spectrum, for example, the thickness of the P -zone 15 can be the 0.2 microns previously recited for the corresponding zone 15 in F1G.1.

Detection of the beams 11 is accomplished by means of the voltage detector 27.3 connected across metal electrodes 27.] and 27.2. The instantaneous value of the voltage supplied by the linear sawtooth voltage source 24 to the

electrode plates

22 and 23 determines which particular one of the beams 11 is being sensed by the detector 27.3 as to that particular beam's instantaneous presence or absence at the front surface 14, in accordance with the pattern of light in the beams 15.6.

It should be understood that the drawing in H0. 2 shows only a one-dimensional (horizontal) pattern oflight, only for the sake of clarity. Two-dimensional patterns can be detected by providing another deflection voltage source connected to vertical deflecting plates (not shown) at the top and bottom surfaces of the body 12, similar to the

horizontal deflecting plates

22 and 23 on the sidewall surfaces. Typically, the voltage supplied to such vertical deflecting plates is a staircase voltage synchronized to the sawtooth voltage of the source 24. Thereby, horizontal and vertical scanning of the two-dimensional pattern of light can be achieved in fashion analogous to a conventional type of scanning in present day camera tubes.

FIG. 2.1 shows an electronic camera apparatus, which is similar to that shown in FIG. 2, but with somewhat different detection means. Again, the same reference numerals are used in FIG. 2.1 as in FIGS. 2 and 1 to identify identical elements common to all of these figures. However, the semiconductor body 12.1 shown in FIG. 2.1 differs from the semiconductor body 12 shown in FIG. 2 in the addition of a P-type zone 27.5 within an island shaped portion 17.1 of the N-zone 17. it should be noted that the island portion 17.1 is contacted by the central electrode 27.2. Moreover. the island 17.1 is separated from the N-zone 17 by portions of the I-zone 16 which extend all the way to the front surface 14 of the body 12.1. A P-N junction 27.6 which intersects the front surface 14 is thus formed at the interface between the P-type zone 27.5 and the N-type island 17.1.

The central contact electrode 27.2 advantageously has a slightly smaller cross section that the P-zone 27.5, so that the N-type island 17.1 is floating" in the electrical sense.

q a conventional transistor. A load resistor 20.1, whose re sistance is denoted by R is connected in series with the battery 20. The current in this resistor 20.1 serves as a monitor type of detector of the beams 11 if and when they strike the front of the body 12.] at a position inside the ring electrode 27.1.

The detection process by the resistor 201 may be understood from the following explanation. If and when one of the beams 11 strikes the floating island N-zone 17.1 then the voltage across the P-N junction 27.6 is thereby changed. This change in voltage across the junction 276 is caused by the accumulation of charges from the beam 11 in this N-zone 17.]. As a result of this change in voltage across the junction 27.6, the current (due to holes emitted by the P-type zone 27.5) is also changed in the PNlP-type transistor structure formed by the zones 27.5, 17.1, 16, and 15, respectively. This current (of holes) is collected by the P"-zone 15 and detected by the load resistor 20.1. Moreover, this latter change in the current, as detected in the resistor 20.1, is greater than the current in the beam 11 itself which strikes inside the ring electrode 27.1, due to the effect of current gain in the PNlP-type transistor structure. Thus, the detection scheme shown in FIG. 2.1 inherently has the property of gain, as in the conventional transistor.

It should be understood that the load resistance R, of the resistor 20.1 should be sufficiently small so that during operation the voltage across the l-zone 16 is not substantially reduced when any of the beams 11 strikes the region between the central electrode 27.2 and the ring electrode 27.1; for then the current in the resistor 20.1 produces an increased voltage drop thereacross, which tends to reduce the voltage drop across the l-zone 16. As an alternative, a load resistor may be placed in series with the battery 27.4 to detect the charge carrier beams 11, instead ofin series with the battery 20.

FIG. 2.2 shows a solid-state electronic camera apparatus, similar to that shown in FIG. 2, but with a thin semitransparent layer of metal 15.11 (instead of the previously described P zone 15) serving as a noninjecting Schottky barrier at the rear surface 13 of the l-zone 16. Typically, this layer of metal 15.11 is essentially aluminum about 50 to A. thick. The layer of metal 15.11 advantageously forms a Schottky barrier with the 1zone 16, in order to prevent injection of unduly large numbers ofcharge carriers into zone 16. Thereby, the 1-zone 16 is substantially depleted of mobile charge carriers by r son of the electric field in the x direction produced by the battery 20. However, if and when the optical source 15.5 shines the beams of light 15.6 into the l-zone 16, then the beams 11 of charge carriers are created in the same pattern as of the beam 15.6, and are propagated through this l-zone 16.

FIG. 3 shows another solid-state charge carrier deflection apparatus in accordance with another embodiment of this invention. The difference between this embodiment and the one shown in FIG. 1 is in the electron beam detection portion thereof. There are close similarities between these embodi ments; therefore, the same reference numerals have been used to designate those elements which are common to both embodirnents. An electron beam 11, whose cross section is of confined extent in a silicon semiconductor crystal body 32, propagates through the body 32 from a rear planar surface 33 to a front planar surface 34 parallel thereto. The body 32, preferably a single crystal, includes zones 15, 16.1, and 37 of P, 1, 1ltype conductivity, respectively. Here the symbol [1 (homologue of Y-type) refers to zone 37 and represents weakly P-type conductivity silicon, that is, having a conductivity intermediate between l-type and P-type due to a net significant acceptor impurity concentration of the order of i0 per cm. Also,just as in FIG. 1, the symbol I refers to zone and represents strongly P-type conductivity.

Advantageously, zone 16.1 in the body 32 is intrinsic or semi-intrinsic type conductivity semiconductor which is doped with trapping centers lying deep in the forbidden band. Typically, gold impurity atoms in a concentration of the order of IO per cm. are used for the purpose of providing these trapping centers, in order to reduce (kill") the lifetime of holes emanating from the Il-type zone 37, but not to reduce the lifetime of electrons in the beam 11. This is required due to the absence of a rectifying barrier against injection of holes at the front of I-zone 16.1. In any event, it should be understood that the sequence of symbols P, P, II, 1 represents semiconductor zones in decreasing order of conductivity with a difference in conductivity of at least about an order of magnitude between successive zones. The

zones

15 and 37 are relatively thin, of the order of one micron in the x direction; whereas the l-zone 16.1 is relatively thick, of the order of 100 microns in the .r direction. Advantageously, the interfaces of the l-zone 16.1 with

zones

15 and 37 are in the form of mutually parallel planar surfaces, in order to promote a uniform electric field in this I-zone 16.1 just as inside a parallel plate capacitor.

An injecting zone 15.1 of N -type conductivity acts as a source of the electron beam 11. This beam is produced when voltage is applied by the battery 21 through a metal ohmic contact 15.2, typically aluminum or platinum. Rectangular collecting terminal zones 39, of N"-type conductivity, are located in the [Hype zone 37 in order to furnish collecting terminals for the electron beam 11. Typically, these N"zones 39 are formed in the [Hype zone 37 by means of a diffusion of donor impurities therein to a depth of approximately 0.2 micron. Individual electrical current detectors 40, biased in common by the battery 31 are ohmically connected to the N zones 39. Each of the detectors 40 senses the electron beam 11 if and when it strikes the front surface 34 at a location at or adjacent the N 'zone 39 connected to the individual detector. The battery 31 typically supplies a positive voltage of about volts to the N -zones 39, in order to collect the current produced by the beam 11.

It should be emphasized that the detection process in the apparatus shown in FIG. 1 depends upon the existence of a voltage drop between the point(s) of impact of the beam 11 at the surface 14 and the N-zone 18, caused by the electron current flow from this point(s) of impact and the zone 18 through the moderately conducting N-zone 17. Thus, the detectors 25.3, 26.3 and 27.3 are basically voltage detectors, sometimes called passivedetectors. In the apparatus shown in FIG. 3, however, most of the electric charge from the beam 11 flows directly only through that current detector 40 which is connected to the 11 closest to the point(s) ofimpact of the beam 11 with the surface 34. Thus, the detectors 40 are current detectors, sometimes called "active detectors."

Deflection of the electron beam 11 in the vertical 1 direction can be achieved by means of another signal source (not shown) connected to metal plates (not shown) on the top and bottom surfaces of the body 32. In such a case, the collecting electrodes 39 advantageously have a more nearly square or circular outer contour rather than the illustrated elongated rectangular contours of the electrodes 39', and these square or circular-shaped electrodes are then advantageously arrayed in both the y and z directions on the front surface 34. Thereby, a two-dimensional fully solid-state equivalent of a conventional cathode-ray tube can be obtained, with control over both horizontal and vertical deflection.

T e lype zone 37 in conjunction with the N collecting terminal zones 39 in FIG. 3 perform the function of collecting and detecting the electrons in the beam 11. As an alternative thereto, indicated in FIG. 3.1, the previous II-type zone 37 is now an N-type zone 37.5 in conjunction with I" collecting terminal zones 39.1. Advantageously, each of these zones 39.1 has a diameter approximately equal to the diameter of the beam 11. The total cross section area of these zones 39.1

moreover is advantageously at least an order of magnitude less than that of zone 37.5, in order to minimize leakage current. Moreover, the P -zones 39.1 can penetrate all the way down from the front surface 34 into the l-zone 36, as shown in FIG. 3.1; however, alternatively, these zones 39.1 may penetrate to only a relatively small distance from the front surface 34. The choice of the depth of penetration of the P -zones 39.1 depends upon the following considerations. In the I-zone 36, at and near the planar interface 36.1 between this I-zone 36 and the N-zone 37.5, there will exist some recombination states (traps) for electrons. As the beam 11 strikes at this interface 36.1, electrons from this beam 11 will be trapped at these recombination states. If there are a sufficient number of such states to trap a substantial fraction of the electrons in the beam 11 during operation, then the P -zones 39.1 need penetrate only a relatively small fraction of the thickness of N- zone 37.5; for in this case the closest nearby P-zone 39.1 will furnish a corresponding number of holes to recombine with the trapped electrons, thereby creating a current in the particular one of the detectors 40 connected to this particular 1- zone. A forward bias voltage of about 0.5 to 5 volts supplied by the DC source 31.1 to the P-zones 39.1 is sufficient for this current detection process. On the other hand, if there is an insufficient number of recombination states at the interface 36.1, then the P*-zones 39.1 should penetrate in the N-zone 37.5 to within less than a beam electron penetration depth, that is, to within a distance of typically about 0.1 microns from the interface 36.1. Moreover, in this latter case, a reverse bias voltage of about 2 to 5 volts is advantageously supplied by the DC source 31.1 to the P-zones 39.1.

FIG. 3.2 shows yet another alternative to the electron collection and detection portion of the apparatus shown in FIG. 3. The Schottky barrier detection electrodes 39.2 and 39.3 in FIG. 3.2 are made of metal, typically aluminum or platinum. Electrodes 39.2 and 39.3 also provide electrical barriers which prevent injection of holes into the I-zone 36. These electrodes 39.2 and 39.3 are biased by the battery 31.2 which supplies a voltage in the range of about 0 to 5 volts. The electrodes 39.2 and 39.3 can be deposited upon the l-zone 36 by conventional vapor deposition techniques.

As an added feature in the device shown in FIG. 3.2, a zone 36.2 of P-type conductivity lies between the I-zone 36 and the detection electrodes 39.2 and 39.3. The thickness and doping level of this P-zone 36.2 is selected so that the electric field in this zone 36.2 is only slightly below the critical field for avalanche breakdown in the absence of the charge carrier beam 11. In the presence of this charge carrier beam 11 (of electrons), the portion of the Pzone 36.2 in which this beam 11 is present will therefore locally suffer avalanche break down, due to the increased electric field caused by the electrons in the beam. Thereby, the current in the particular one of the detectors 40 in closest proximity to the beam 11 will be much larger than in the absence of the avalanche, due to the avalanche multiplication of charge carriers. Thus, this means for detection of the beam 11, with the added feature of the P- zone 36.2, has gain due to avalanche breakdown. In the event that such gain is not desired, the P-type zone 36.2 is omitted and the Schottky barrier electrodes 27.2 and 27.3 are located directly in physical contact with the I-zone 36. As another alternative, the Schottky barrier electrodes 39.2 and 39.3 can be replaced by diffused or epitaxial N-type zones to which ohmic electrical connections are made from the current detectors 40.

FIG. 4 illustrates yet another embodiment of the invention. The apparatus shown in FIG. 4 functions similarly to that shown in FIG. 1, with the added structural feature of integrated planar type of horizontal and vertical deflection electrodes. The silicon semiconductor body 42, preferably a single crystal, supports an electron beam propagating in a direction from the rear surface 43 of an l-zone 46 to the array of ringtype electrode detectors 57 disposed near the front surface 44 of the I-zone 46. Thus, the I-zone 46 serves as a propagation medium for the charge carrier beam 11. This beam is injected in response to electric fields produced by the battery 4|, just as the battery 21 described above and shown in FIG. 1. The voltage from the battery 41 is applied through a metal ohmic contact 45.2 to an injecting zone 45.] of N -type semiconductor conductivity. This injecting zone 45.! is contained within a P -type zone 45 which is located contiguously along a rear planar surface 43 of the l-zone 46 in the crystal body 42. The Lzone itself is intrinsic or semi-inlrinsic-type semiconductor. that is, of the same conductivity type as the l-zone l6 previously discussed above in connection with the description of the body 12.

The N-zone 47 is typically about 1 micron in thickness, located contiguously with the front surface 44. The N-zone 47 can be formed by conventional methods ofimpurity diffusion. epitaxial growth, or ion implantation. Advantageously, the rear surface 43 and the front surface 44 of the l-zone 46 from a pair of mutually parallel planar and substantially equipotential surfaces. Moreover, the physical extent in the yz plane of the P"-zone 45 is advantageously approximately the same as that of the N-type zone 47 at the front surface 44 and is located opposite thereto, just as in a parallel plate condenser, in order that the electric field be uniform in the l-zone 46 wherein the electron beam propagates.

Typically, the l l injecting zone 45.! is a donor impurity diffused region about 0.2 micron deep within the P -type region 45. In turn, the P region 45 is an acceptor impurity diffused region about one micron in thickness at the rear planar surface 43v Thus, the N injecting zone 45,] and the P*-zone 45 are similar respectively to the N injecting zone l5.l and the P-zone IS in the apparatus shown in FIG. I, and a P-N junction is likewise formed at the mutual boundary between P- zone 45 and N*-zone 45.1. Likewise, the N terminal zone 48 is a donor diffused region to a depth of about 0.2 micron within the N-zone 47.

Typically, the l-zone 46 between the rear planar surface 43 and the front planar surface 44 is about 100 microns thick in the x direction. In this I-zone 46, the electron beam from the injecting electrode 45.1 undergoes controlled deflections in the horizontal y and vertical z directions, due to electrical signal sources 56.1 and 56.2 applied through metal ohmic electrodes 54.1, 55.1, 54.2, and $5.2 attached to the N deflection electrode zones 52.], 53.1 and 52.2, 53.2, respectively. The battery 10 supplies reverse bias voltage by means ofa wire lead 49.1 to the P region 45, and to the N-zone 47 by means of a wire lead 49 to the N* terminal zone 48 therein. it should be understood that the battery 20 in FIG. 4 produces a uniform electric field for propagating an electron beam in the x direction through the l-zone 46, similarly as the battery 20 in the apparatus shown in FIG. I.

Each of the ring-type detector electrodes 57 is identical to the ring-type electrode pair 27.1-27.2 as previously described in connection with the apparatus illustrated in HO. 1. Moreover, each of the ring-type detector electrodes 57 is It should also be mentioned that it is important that the doping and thickness of the P-zones 15 and 45 (at the rear surface) in FIGS. 1 and 4 should be selected sufficiently great such that these P-zones are not themselves depleted of mobile charge carriers due to impurities.

Although this invention has been described in detail only in terms of the injection and deflection control of an electron beam, a beam of holes can similarly be injected and deflected located in the yz plane between the deflection zones 52.],

53.1, 52.2, 53.2; and each of the detector electrodes 57 is connected to a separate voltage detector 58 (only two of which are shown for the sake of clarity), for sensing the presence vs. absence of the electron beam at the front surface 44 within each ring formed by each ring electrode. Thus, by selecting the electrical source 56.1 to be a linear sawtooth signal and the electrical source 56.2 to be an arbitrary signal, the apparatus shown in FIG. 3 illustrates a fully solid-state equivalent of a conventional cathode-ray tube with both a linear horizontal sweep and a vertical signal deflection.

It should also be mentioned that the N deflection electrode zones 52.1, 53.1, 52.2, 53.2 in FIG. 4 may alternatively be placed on the rear surface 43 instead of the front surface 44. In such a case, where these deflection electrode zones are locuted on the rear surface, then instead of (strongly) P*-type conductivity, the zone 45 should be made only (moderately) P-type conductivity, especially in the neighborhood of these N deflection electrode zones. Thereby, the sheet resistance of the zone 45 is sufficiently high to prevent unduly large leakage currents.

in conjunction with homologous semiconductor structures, that is, by interchanging homologous conductivity types (P with N' P with N, and [I with Y) everywhere in the abovedescribed devices. Moreover, other semiconductors instead of silicon can be used in this invention, such as germanium, gallium arsenide, or other Group IV and Group lll-V semiconductors. Also, instead of transverse electric fields, transverse magnetic fields can be used to achieve horizontal and vertical control of the electronic beam. Moreover, although the front surface and rear surface of the semiconductor body in the specific embodiments are shown as rectangularly shaped, any pair of arbitrarily shaped surfaces can be used in this invention. Finally, it should be understood by the skilled worker that various combinations and interchanges of the features shown in the detailed embodiments can be made by way of substitutions in order to perform similar functions.

For example, the detection means used in the apparatus shown in FIG. 3.] can be used as detection means in the ap paratus shown in FIG. 2.

What we claim is:

l. A solid-state charge carrier beam deflection apparatus which comprises:

a. a single crystal semiconductor body having therein a first zone, the first zone characterized by a relatively high resistivity and by a geometrical boundary surface which includes opposed first and second major surfaces;

b. means for injecting a charge carrier beam containing charge carriers of a first type for propagation inside the first zone the beam having a cross section area at least an order of magnitude less than the area of either of said major surfaces;

c. means for producing in the first zone a longitudinal electric field sufficient to deplete substantially all the mobile charge carriers due to impurities in the first zone and to propel the charge carriers in the beam in the first zone, the electric field characterized by a first equipotential surface substantially coincident with the first major surface and by a second equipotential surface substantially coincident with the second major surface;

d. means for detecting the position of the beam at the second major surface; and

e. means for deflecting the charge carrier beam in the first zone transverse to the direction of propagation for varying the trajection of the beam between the first and second major surfaces.

2. Apparatus in accordance with claim 1 which further includes an electrical rectifying barrier at the second major surface, which prevents the injection in the first zone of charge carriers of opposite type from the first type of charge carriers in the charge carrier beam.

3. Apparatus according to claim 1 in which the means for detecting the charge carrier beam includes first and second metal electrodes, the first electrode being in the shape of a ring surrounding the second electrode, and both electrodes located on an external surface of the body on the opposite side of the second major surface from the first major surface.

4. Apparatus according to claim 1 in which the second major surface is covered with a second semiconductor zone in the body having a conductivity type in which the charge car riers in the beam constitute majority carriers, and in which the third means for detecting the position of the beam at the second major surface includes a seventh semiconductor zone in the body of opposite conductivity type from that of the second zone, the seventh zone located contiguously with an external surface of the body on the opposite side of the second major surface from the first major surface, the seventh zone forming a junction with the second zone.

5. Apparatus according to claim 1 in which the means for producing the longitudinal electric field includes a second semiconductor zone in the body located contiguously with respect to the second major surface, the second zone being of a conductivity type in which the charge carriers in the beam constitute majority carriers; and in which the means for detecting the position of the beam at the second major surface includes a seventh semiconductor zone in the body of opposite conductivity type from the second zone, the seventh zone located contiguously with an external surface of the body on the opposite side of the second major surface from the first major surface, the seventh zone forming a junction with the second zone, the seventh zone located underneath a first electrode contiguous thereto. and a second electrode in the shape of a ring surrounding the first electrode and located contiguously with respect to the second zone on the third surface of the body, the area of the cross section within the ring being at least an order of magnitude less than that of the second major surfacev 6. Apparatus in accordance with claim 5 which the means for deflecting includes means for producing a second electric field within the first zone in a second direction at right angles to the first direction, and means for producing a third electric field within the first zone in a third direction different from the second direction and at right angles to first direction.

7v The apparatus recited in claim 1 in which the semiconductor body is silicon and the first zone thereof has a resistivity of approximately lOkfl-cm.

8. Apparatus according to claim 7 in which the distance between the first major surface and the second major surface is approximately 100 microns.

9. Apparatus according to claim 1 in which the means for detecting the beam includes:

detector electrode means disposed in physical contact with the body on an external surface thereof which is located on the opposite side of the second major surface from the first major surface.

10. Apparatus according to claim 9 in which the means for deflecting the charge carrier beam in the first zone include means for producing a second electric field in the first zone in a transverse direction.

ll. Apparatus according to claim l in which the means for deflecting the charge carrier beam includes a pair of electrode means disposed on mutually opposite sides of the first zone, and a voltage signal source attached across said pair of electrode means.

12. Apparatus according to claim 9 in which the means for producing the longitudinal electric field includes a second semiconductor zone of moderate conductivity in the body, the second zone located contiguously with the second surface of the first zone, the second zone having a conductivity type such that the charge carrier in the beam are majority carriers in the second zone.

13. Apparatus according to claim 12 in which the means for deflecting the charge center beam includes third and fourth semiconductor zones adapted for connection to an external voltage signal source and located contiguous with the second zone, the third and fourth zones being of the same conductivity type as the second zone but having higher conductivities than the second zone, the coordinate of the detector electrode in the second direction being located between the third and fourth zones.

14. Apparatus according to claim 1 in which the means for injecting the beam includes a metal layer disposed on the first surface forming a Schottky barrier at the interface with the first zone in the presence of the longitudinal electric field.

15. Apparatus according to claim 14 in which the means for injecting the charge carrier beam includes a source of a pattern of optical radiation incident upon the metal layer.

16. Apparatus according to claim 1 in which an electrical rectifying barrier is provided in the presence of the first electric field in the first zone by a fifth semiconductor zone in the body disposed upon the first major surface, the fifth zone being of the conductivity type in which the charge carriers in the beam constitute minorit carriers in the fifth zone.

17. Apparatus according 0 claim 16m which the means for injecting the charge carrier beam includes a sixth semiconductor zone of opposite conductivity type from the fifth zone, the sixth zone being located in the body contiguously with respect to the fifth zone at an external surface thereof on the other side of the first major surface from the second major surface, and the sixth zone having a cross section which is at least an order of magnitude less than the cross section of the fifth zone.

18. Apparatus according to claim 16 in which the means for injecting include a source of a pattern of optical radiation incident upon the fifth zone.

Claims

1. A solid-state charge carrier beam deflection apparatus which compriseS: a. a single crystal semiconductor body having therein a first zone, the first zone characterized by a relatively high resistivity and by a geometrical boundary surface which includes opposed first and second major surfaces; b. means for injecting a charge carrier beam containing charge carriers of a first type for propagation inside the first zone the beam having a cross section area at least an order of magnitude less than the area of either of said major surfaces; c. means for producing in the first zone a longitudinal electric field sufficient to deplete substantially all the mobile charge carriers due to impurities in the first zone and to propel the charge carriers in the beam in the first zone, the electric field characterized by a first equipotential surface substantially coincident with the first major surface and by a second equipotential surface substantially coincident with the second major surface; d. means for detecting the position of the beam at the second major surface; and e. means for deflecting the charge carrier beam in the first zone transverse to the direction of propagation for varying the trajection of the beam between the first and second major surfaces.

4. Apparatus according to claim 1 in which the second major surface is covered with a second semiconductor zone in the body having a conductivity type in which the charge carriers in the beam constitute majority carriers, and in which the third means for detecting the position of the beam at the second major surface includes a seventh semiconductor zone in the body of opposite conductivity type from that of the second zone, the seventh zone located contiguously with an external surface of the body on the opposite side of the second major surface from the first major surface, the seventh zone forming a junction with the second zone.

5. Apparatus according to claim 1 in which the means for producing the longitudinal electric field includes a second semiconductor zone in the body located contiguously with respect to the second major surface, the second zone being of a conductivity type in which the charge carriers in the beam constitute majority carriers; and in which the means for detecting the position of the beam at the second major surface includes a seventh semiconductor zone in the body of opposite conductivity type from the second zone, the seventh zone located contiguously with an external surface of the body on the opposite side of the second major surface from the first major surface, the seventh zone forming a junction with the second zone, the seventh zone located underneath a first electrode contiguous thereto, and a second electrode in the shape of a ring surrounding the first electrode and located contiguously with respect to the second zone on the third surface of the body, the area of the cross section within the ring being at least an order of magnitude less than that of the second major surface.

6. Apparatus in accordance with claim 5 which the means for deflecting includes means for producing a second electric field within the first zone in a second direction at right angles to the first direction, and means for producing a third electric field within the first zone in a third direction different from the second direction and at right angles to first direction.

7. The apparatus recited in claim 1 in which the semicoNductor body is silicon and the first zone thereof has a resistivity of approximately 10k Omega -cm.

9. Apparatus according to claim 1 in which the means for detecting the beam includes: detector electrode means disposed in physical contact with the body on an external surface thereof which is located on the opposite side of the second major surface from the first major surface.

11. Apparatus according to claim 10 in which the means for deflecting the charge carrier beam includes a pair of electrode means disposed on mutually opposite sides of the first zone, and a voltage signal source attached across said pair of electrode means.

13. Apparatus according to claim 12 in which the means for deflecting the charge carrier beam includes third and fourth semiconductor zones adapted for connection to an external voltage signal source and located contiguous with the second zone, the third and fourth zones being of the same conductivity type as the second zone but having higher conductivities than the second zone, the coordinate of the detector electrode in the second direction being located between the third and fourth zones.

16. Apparatus according to claim 1 in which an electrical rectifying barrier is provided in the presence of the first electric field in the first zone by a fifth semiconductor zone in the body disposed upon the first major surface, the fifth zone being of the conductivity type in which the charge carriers in the beam constitute minority carriers in the fifth zone.

17. Apparatus according to claim 16 in which the means for injecting the charge carrier beam includes a sixth semiconductor zone of opposite conductivity type from the fifth zone, the sixth zone being located in the body contiguously with respect to the fifth zone at an external surface thereof on the other side of the first major surface from the second major surface, and the sixth zone having a cross section which is at least an order of magnitude less than the cross section of the fifth zone.