CN102280332A

CN102280332A - MIPM (multum in parvo mapping)-type internal field emitting cathode

Info

Publication number: CN102280332A
Application number: CN2011101845143A
Authority: CN
Inventors: 邹宇; 展长勇; 林黎蔚; 任丁; 刘波; 黄宁康; 肖婷
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2011-07-04
Filing date: 2011-07-04
Publication date: 2011-12-14
Anticipated expiration: 2031-07-04
Also published as: CN102280332B

Abstract

A cathode of the invention belongs to the field of vacuum electronics and the materials science, and in particular relates to an MIPM (multum in parvo mapping)-type internal field emitting cathode. The MIPM-type internal field emitting cathode is composed of a bottom electrode layer, an insulating layer, an electronic storage transmission layer and a top electrode layer; the emitting cathode is mainly characterized in that the electronic storage transmission layer adopts a porous silicon film material. In an alternating current AC driving mode, a functional layer not only can transport electrons, but also can store the electrons so as to improve the emitting efficiency. Compared with the prior art, the MIPM-type internal field emitting cathode has the advantages of great emitting current and good stability; and due to the strong environment adaptability, the cathode not only can work in the gas, but also can work in the liquid.

Description

Field-transmitting cathode in a kind of MIPM type

Technical field

The invention belongs to vacuum electronics and materialogy field, relate in particular to field-transmitting cathode in a kind of MIPM type.

Background technology

The field-causing electron emission has three types: the one, and the outfield causes emission, and the 2nd, interior field emission, the 3rd, transverse field emission.

Preparations such as outer field emissive cathode useful metal or semiconductor vertebra point, nanotube, nano wire, its principle is to utilize outside highfield to constrain surface potential barrier, the peak of potential barrier is reduced, and make the narrowed width of potential barrier, when cold cathode surface potential barrier width is compressed to when can be with electron wavelength comparable by electric field, because of the tunnel effect of electronics, a large amount of electronics pass surface potential barrier and overflow.The transverse field emission principle is to utilize the conduction current formation electronics emission of discontinuous film or nano slit to be drawn by vertical electric field, is called the surface conductive negative electrode again.The principle of interior field emission is to utilize inner high field to make electronics enter dielectric layer from substrate, and quickens in dielectric layer and obtain enough energy, effusion dielectric layer.Because the internal electric field of interior field-transmitting cathode is not influenced by extraneous atmosphere, therefore interior field emission is insensitive to surface topography and gas absorption etc.The field pattern emitting cathode can be divided again on structure and the principle and comprise three kinds at present: a kind of is metal-insulator-metal (Metal-Insulator-Metal, MIM) type, another is metal-porous silicon-metal (MPM) metal-porous silicon-metal mold (Metal-Porous Silicon-Metal, MPM) type, the third is metal-insulator layer-semiconductor layer-metal (Metal-Insulator-Semiconductor-Metal, MISM) type.

Electronics because the scattering process electronics can lose most of kinetic energy, cause most of electronics not launch from the top metal electrode, thereby the emission effciency of mim type negative electrode is not high when passing through the insulating barrier of mim type negative electrode.The MPM type is the people such as Nobuyoshi Koshida (Jpn. J. Appl. Phys. Vol. 34,1995, the pp. L705-L707) that propose of nineteen ninety-five Japan.A large amount of nano-silicon crystal grain are arranged in the porous silicon, and when electronics passed through therein, because quantum tunneling effect, the energy of loss was fewer.Compare mim type, this MPM type negative electrode, the grid operating voltage can be reduced in 20 V, and its cathode electronics emission effciency has surpassed 10% at present, but emission effciency stability is not good.Japan is a kind of MPM type negative electrode of report recently, and grid voltage is 16 V, and the emission effciency of working after 5 hours drops to 1.6% from 2.1%, and fall is 23%.

MISM type negative electrode drives with alternating current, and its operation principle is as follows: at the negative half period of AC drive voltage, the bottom electrode current potential is for just, and the electronics utmost point from power on is injected on the interface of semiconductor layer and insulator layer, exists on the interface with the form of interfacial state electronics.When voltage reversal, the electronics on the interface comes back in the semiconductor layer, and obtains therein quickening, and enters top electrode then, and the surface potential barrier that the electronics that portion of energy is big can overcome top electrode is transmitted in the vacuum.The advantage of this negative electrode is that the electronics launch stability is good, and shortcoming is that emission effciency is not high.Domestic patent (application number 01140447.7, Granted publication CN 1142572C) semiconductor layer in this structure (being called electron transfer layer in this patent) is improved, adopted from the content gradually variational of high electron affinity and made semiconductor layer to the film of the component of low electron affinity, emission effciency surpasses 0.5%, but emission effciency still can not satisfy the demand (as Field Emission Display) of practical application, and its performance still requires further improvement.

Summary of the invention

The technical problem that the present invention will solve is that the field emission type cathode emission efficiency is not high in the existing MISM type, the shortcoming that emission is low.

For addressing the above problem, the general semiconductor layer that the present invention replaces in the MISM type negative electrode with porous silicon forms a kind of MIPM type (Metal-Insulator-Semiconductor-Metal, metal-insulator layer-porous silicon-metal) interior field-transmitting cathode, comprise four function film layers of combining closely from top to bottom: bottom electrode layer 1, insulating barrier 2, electron storage transmitting layer 3 and top electrode layer 4, it is characterized in that, described bottom electrode layer material is metal or alloy Hou Du ≧ 10 nm, described top electrode layer material is the metal of low electron affinity energy, alloy, the diamond like carbon or the semiconductor that mix, thickness is 5 nm ~ 500 nm, described insulating layer material is a metal oxide, the tetrels oxide, pottery or mica, thickness is 100 nm ~ 1 μ m, described electron storage transport layer material is a n type porous silicon, and thickness is 10 μ m ~ 500 μ m.

Field-transmitting cathode in the described MIPM type is characterized in that the average conductivity of described n type porous silicon is 0.005 Ω * cm ~ 3 Ω * cm, and mean porosities is 5% ~ 80%, and average pore size is 1 nm ~ 100 μ m.

Be operated in negative half period when negative electrode is subjected to AC driving, promptly the bottom electrode current potential is timing, and for field-transmitting cathode in traditional MISM type, the electronics utmost point from power on is injected on the interface of semiconductor layer and insulator layer, exists on the interface with the form of interfacial state electronics; For field-transmitting cathode in the MIPM type provided by the invention, electronics not only can be stored on the interface of semiconductor layer and insulator layer but also can be stored in the porous silicon layer, thereby has guaranteed the density of efficient and emission current.This is that porous silicon can be " charged up " when being operated in the back bias voltage of interchange because a large amount of nanocrystalline crystal boundaries that exist can be caught a large amount of electronics in the porous silicon.Electronics is driven by the internal field and can form big current emission when operating voltage is reverse.This mode of operation had both guaranteed the emission effciency of interior field-transmitting cathode, had also guaranteed the stability of work.In this field-transmitting cathode can not only liquid, work in atmosphere or the vacuum, and can under extreme conditions such as high temperature, high radiation, work.

Description of drawings

The structural representation of field-transmitting cathode in Fig. 1 MIPM type.

Embodiment

The invention will be further described below in conjunction with accompanying drawing.

Embodiment 1

Consult Fig. 1, the material of this hearth electrode 1 is a gold, and thickness is 500 nm; The material of this insulating barrier 2 is SiO ₂, thickness is 100 nm; This electron storage transmitting layer 3 material is a porous silicon, and thickness is 40 μ m, and its average conductivity is 0.01 Ω, and mean porosities is 50%, average pore size is 30 nm; These top electrode 4 materials are gold, and thickness is 15 nm.10 ^-5Under the torr air pressure, recording emission effciency is 1.5%, and continuous operation is attenuation of beam 1% after 20 hours.

Embodiment 2

Consult Fig. 1, the material 1 of this hearth electrode is a chromium, and thickness is 200 nm; The material of this insulating barrier 2 is HfO ₂, thickness is 300 nm; This electron storage transmitting layer 3 material is a porous silicon, and thickness is 40 μ m, and its average conductivity is 0.01 Ω, and mean porosities is 50%, average pore size is 50 nm; These top electrode 4 materials are Ag, and thickness is 10 nm.10 ^-5Under the torr air pressure, recording emission effciency is 1.5%, and continuous operation is attenuation of beam 1% after 20 hours.

Embodiment 3

Consult Fig. 1, the material of this hearth electrode 1 is Ag, and thickness is 200 nm; The material of this insulating barrier 2 is Ta ₂O ₅, thickness is 400 nm; This electron storage transmitting layer 3 material is a porous silicon, and thickness is 30 μ m, and its average conductivity is 0.01 Ω, and mean porosities is 50%, average pore size is 30 nm; These top electrode 4 materials are ZrN, and thickness is 8 nm.10 ^-5Under the torr air pressure, recording emission effciency is 1.3%, and continuous operation is attenuation of beam 1% after 20 hours.

Claims

1. field-transmitting cathode in the MIPM type, it comprises four function film layers that connect successively: bottom electrode layer, insulating barrier, electron storage transport layer and top electrode layer, it is characterized in that, described bottom electrode layer material is metal or alloy Hou Du ≧ 10 nm, described top electrode layer material is the metal of low electron affinity energy, alloy, the diamond like carbon or the semiconductor that mix, thickness is 5 nm ~ 500 nm, described insulating layer material is a metal oxide, the tetrels oxide, pottery or mica, thickness is 100 nm ~ 1 μ m, described electron storage transport layer material is a n type porous silicon, and thickness is 10 μ m ~ 0.5 mm.

2. field-transmitting cathode in the MIPM type as claimed in claim 1 is characterized in that the average conductivity of described n type porous silicon is 0.005 Ω * cm ~ 3 Ω * cm, and mean porosities is 5% ~ 80%, and average pore size is 1 nm ~ 100 μ m.