CN113410110B

CN113410110B - Semiconductor vacuum diode

Info

Publication number: CN113410110B
Application number: CN202110513830.4A
Authority: CN
Inventors: 沈志华; 李巧宁; 葛滨; 董新奕; 姜林林
Original assignee: Nantong Vocational College
Current assignee: Nantong Vocational College
Priority date: 2021-05-07
Filing date: 2021-05-07
Publication date: 2023-08-08
Anticipated expiration: 2041-05-07
Also published as: CN113410110A

Abstract

The invention discloses a semiconductor vacuum diode, which is formed by sequentially superposing three material layers, namely an electrode A, a dielectric body and a semiconductor electrode B, wherein the electrode A is made of a metal material with a lower work function, a through vacuum channel is arranged in the middle of the dielectric body, and the electrode B is made of a heavily doped semiconductor material; when in use, the electrode A and the electrode B are respectively connected with one electrode of the direct current power supply. The diode has the advantages of stable working performance under high-temperature high-radiation environment, more excited electrons, larger current, high tolerance to process deviation of the thickness of the dielectric layer in the preparation process, and the like.

Description

Semiconductor vacuum diode

Technical Field

The invention relates to a vacuum diode used in the electronic industry.

Background

A common structure of a vacuum diode is to place two electrodes spaced apart from each other in a vacuum glass tube, and an electric heating element is provided near one of the electrodes (negative electrode) to excite electrons.

With the development of the semiconductor technology, solid-state electronic devices, such as MOSFETs, have gradually replaced vacuum electronic devices, such as vacuum diodes and triodes, in many fields, and compared with vacuum electronic devices, solid-state electronic devices have many advantages of simple manufacturing process, low cost, small volume, easy integration on integrated circuits, and the like. However, the vacuum electronic device has the advantages of large working current, more stability under high radiation, high temperature and other environments, and the like, so that the vacuum electronic device is still not replaced in some special fields.

The work function of a metal is the minimum energy (typically in electron volts) that must be provided to allow a particle of electrons to immediately escape from the solid surface. Work function is an important attribute of metals, and its size is generally about one half of the ionization energy of free atoms of metals, and by using work functions of different metals, new technical products can be constructed.

Application number: 2014106918549 discloses a processing method of a vacuum diode, which comprises the following steps: a. welding one ends of two first nickel plates on an anode and bending the first nickel plates to form an anode bracket assembly; b. one end of a second nickel sheet is welded with a metal lead of a first core column with a filament, and the other end of the second nickel sheet is welded with a metal lead at the top of the second core column to form an insulating bracket; c. the two first tantalum sheets are welded at the bottom of the cathode in a staggered manner, and the first tantalum sheets and the third nickel sheets are respectively welded to form a cathode bracket assembly; d. welding a third nickel sheet on the metal lead at the top of the first core column, and welding a cathode with the metal lead of the first core column through the bottom of the second tantalum sheet; e. arranging the diode foundation structure in a glass tube to form a vacuum diode; the upper surface of the cathode is parallel to the lower surface of the anode. The vacuum diode glass tube is easy to break, and the electric auxiliary heating consumes additional energy.

Disclosure of Invention

The invention aims to:

the invention provides a novel semiconductor vacuum diode, which realizes the preparation of a vacuum electronic device by adopting a special structural shape through a traditional processing technology, combines the advantages of the traditional solid electronic device and the vacuum electronic device, and has the advantages of stable and high working performance, high tolerance to medium layer thickness deviation and the like under a high-temperature and high-radiation environment.

The technical scheme is as follows:

the invention relates to a semiconductor vacuum diode, which is formed by sequentially superposing three material layers of an electrode A, a dielectric body and an electrode B (a three-layer film structure or a three-layer plate structure which are tightly connected is manufactured by adopting magnetron sputtering, chemical vapor deposition, electron beam evaporation or cementing technology), wherein the electrode A is made of metal, a vacuum channel which penetrates through upper and lower material layers is arranged in the middle of the dielectric body (a connecting channel which can be partially sunken is arranged in the electrode A or the electrode B, and the diameter of the connecting channel of the electrode A and the electrode B is smaller than that of the vacuum channel of the dielectric body, so that electrons can be conveniently emitted or collected in a concentrated mode). The electrode B is made of a heavily doped semiconductor material (an N-type or P-type silicon wafer, and can provide more free electrons or holes respectively); in use, electrode A and electrode B are used to connect to one electrode of a DC power supply, respectively.

Preferably, the electrode A is made of metal with a lower work function, and the electrode B is made of heavily doped P-type semiconductor; when in use, the electrode A is connected with the negative electrode of the direct current power supply, and the electrode B is connected with the positive electrode of the direct current power supply. It is further preferred that electrode a be a relatively inexpensive, readily etchable, relatively stable material (e.g., lithium metal, magnesium metal, etc.) with a relatively low work function.

Or the electrode A is made of metal material with lower work function, and the electrode B is made of heavily doped N-type semiconductor material; when in use, the electrode A is connected with the positive electrode of the direct current power supply, and the electrode B is connected with the negative electrode of the direct current power supply.

The dielectric body is an organic film or an inorganic film, preferably a high dielectric ceramic film or a ceramic sheet, and has good insulation and a high dielectric constant. The structure of the invention is similar to a capacitor, the dielectric constant is high, the capacitance value is large, the charge enriched between two polar plates of the capacitor or in a vacuum channel (preferably a narrow channel with width smaller than height, the capacitance drop is small) is more, and the current in a circuit is large.

The vacuum channels may be obtained by dry etching or wet etching or machining processes. The dielectric layer thickness is typically controlled below 100nm, resulting in a vacuum channel length and electron mean free Cheng Xiangjin in an atmospheric environment, in which case such devices can operate in an atmospheric environment with similar effects as in a vacuum environment.

The electrode A is provided with a hole communicated with the vacuum channel of the dielectric body, and a metal cover plate layer is arranged above the electrode A, and the metal cover plate is made of metal with higher function; when the electrode is used, the electrode A or the metal cover plate is connected with one pole of the direct current power supply, and the electrode B is connected with the other pole of the direct current power supply.

The metal cover plate adopts a metal material with stable chemical property, and is made of gold (or gold plating), silver (or silver plating), nickel or carbon (preferably graphene with high mechanical strength and good conductivity) as an electron collecting and protecting layer.

When the diode is biased, charge aggregation is formed at one side of the interface between the electrode A and the dielectric layer, which is close to the electrode A, so that quasi-two-dimensional electron gas is formed, and electrons close to the vacuum channel are subjected to coulomb repulsive force of other electrons in the vacuum channel, so that surface potential barriers are easily overcome, and electron emission is formed. Depending on the magnitude of the bias applied, the electron emission follows different emission laws.

In the present invention, the bias voltage applied to the diode is usually below 5V, and the electron emission rule follows the rule of limiting current by space charge in thermionic emission. In this working state, the current in the diode is independent of temperature, so that stable operation can be realized in a larger temperature range, and the highest working temperature can reach 650 ℃ (melting point temperature) by taking the electrode A (cathode) material as magnesium metal for example.

The present invention focuses on the space charge confinement region in thermionic emission. In the prior art, no research is conducted on the characteristics of the device under the space charge limiting region, the temperature stability characteristic and the process stability of the device working under the space charge limiting region are emphasized, and the device can be used as a diode device which stably works in a larger temperature range based on the working mechanism and is suitable for mass production of devices with uniform performance.

The beneficial effects are that:

compared with solid-state electronic devices, such as PN junction diodes, the vacuum diode provided by the invention can stably work at a higher temperature. In conventional semiconductor diodes, charge transport occurs in semiconductor materials that have significant intrinsic excitation at high temperatures (typically no higher than 200 ℃), with large leakage currents, and the diode can fail. The vacuum diode conducting channel provided by the invention is vacuum and is not affected by temperature. Meanwhile, the current cannot change obviously along with the temperature rise under the influence of the space charge limiting current.

Compared with vacuum electronic devices, such as field emission vacuum diodes, the field emission cathode is usually of a tip structure, the preparation is complex, the tip structure can be degraded due to arc discharge and other factors in the use process, and the reliability is poor. The vacuum diode provided by the invention has lower working voltage. In order to ensure significant field emission current, the operating voltage of the field emission vacuum diode is usually above 10V, while the operating voltage of the vacuum diode provided by the invention is usually below 5V to realize electron excitation.

Under the diode structure and the electron emission rule, the relation between the diode current and the thickness of the dielectric layer is smaller, and the tolerance to the thickness process deviation of the dielectric layer is higher.

Drawings

FIG. 1 is a schematic view of a construction of the present invention;

FIG. 2 is a schematic illustration of a connection structure of the present invention in use;

fig. 3 is a schematic view of another connection structure of the present invention in use.

FIG. 4 is a graph of data for current changes at different temperatures in the diode of FIG. 2;

fig. 5 is a graph of current versus dielectric layer thickness for the diode of fig. 2.

In the figure, 1-electrode B; 2-mesosome; 3-electrode A; 4-vacuum channels; 5-metal cover plate.

Detailed Description

Embodiment one:

the semiconductor vacuum diode of fig. 1 is a three-layer film structure or a three-layer plate structure formed by sequentially stacking three materials, namely an electrode a, a dielectric body and an electrode B; the electrode A is made of metal material with lower work function, a vacuum channel penetrating the upper material layer and the lower material layer is arranged in the middle of the dielectric body, and the electrode B is made of heavily doped semiconductor material; in use, as shown in fig. 2 or 3, electrode a and electrode B are used to connect to one electrode of a dc power supply, respectively.

For the vacuum diode device provided by the invention, electromagnetic simulation software based on a finite integration technology is adopted to simulate the device characteristics, and the result is shown in fig. 4 and 5. In the simulation process, the structure of FIG. 2 is adopted, and other key parameters include the thickness of the dielectric layer being 60nm, and the radius of the vacuum channel being about 30 μm. As can be seen from fig. 4, at higher temperatures (device operating in space charge confinement region), the current in the diode remains unchanged as the temperature increases, i.e., stable operation at high temperatures can be achieved. And the lower the operating voltage, the wider the temperature range over which the diode operates steadily. As can be seen from fig. 5, under a certain working voltage, the current in the diode changes little with the thickness of the dielectric layer, so that high tolerance to the process deviation of the thickness of the dielectric layer is realized.

Embodiment two:

in fig. 2, diode electrode B is applied with a positive voltage (positive electrode), electrode a is applied with a negative voltage (negative electrode), a quasi-two-dimensional electron gas is formed on the electrode a side at the interface of electrode a and the dielectric layer, and electrons are emitted from the electrode a near the interface and collected by electrode B.

Embodiment III:

fig. 3 shows a structure of fig. 2, wherein a layer of electrode material is added and covered over the vacuum channel, the diode electrode a is applied with a positive voltage, the electrode B is applied with a negative voltage, and the vacuum channel is used for collecting electrons excited by the electrode B and transmitting the electrons to the electrode a or the metal cover plate.

Claims

1. A semiconductor vacuum diode is formed by sequentially superposing three materials of an electrode A, a dielectric body and an electrode B to form a three-layer film structure or a three-layer plate structure, wherein a vacuum channel penetrating through an upper material layer and a lower material layer is arranged in the middle of the dielectric body, and a hole communicated with the vacuum channel of the dielectric body is formed in the electrode A, and the semiconductor vacuum diode is characterized in that: the electrode A is made of a metal material with a lower work function, a metal cover plate layer made of a metal material with a higher work function is arranged above the electrode A, and the electrode B is made of a heavily doped semiconductor material; when the electrode is used, the electrode A or the metal cover plate is connected with one pole of the direct current power supply, and the electrode B is connected with the other pole of the direct current power supply.

2. A semiconductor vacuum diode as claimed in claim 1, wherein: when the electrode B is made of a heavily doped P-type semiconductor material, the electrode A is connected with the negative electrode of the direct current power supply, and the electrode B is connected with the positive electrode of the direct current power supply; when the electrode B is made of heavily doped N-type semiconductor material, the electrode A is connected with the positive electrode of the direct current power supply, and the electrode B is connected with the negative electrode of the direct current power supply.

3. A semiconductor vacuum diode as claimed in claim 1 or 2, characterized in that: the diameter of the hole of the electrode A is smaller than the diameter of the dielectric vacuum channel.

4. A semiconductor vacuum diode as claimed in claim 1 or 2, characterized in that: the electrode A is made of metal lithium or metal magnesium; the metal cover plate is made of gold, copper gold plating, silver, copper silver plating, nickel or copper nickel plating or graphene.