Variable doping structure of transmission-type photoelectric cathode material for enhancing thermal stability

Abstract

The invention discloses a variable doping structure of a transmission-type photoelectric cathode material for enhancing thermal stability. An AlGaAs corrosion barrier layer, a GaAs zinc heavy doping layer, a GaAs zinc light doping layer, a GaAs carbon gradient doping layer, a GaAs spacer layer and an AlGaAs window layer are arranged sequentially upwards on a GaAs100 substrate material layer. The variable doping structure of the transmission-type photoelectric cathode material for enhancing the thermal stability has the advantages of: enhancing short wave response of a transmission-type GaAs or InGaAs photoelectric cathode and improving the thermal stability during the photoelectric cathode technical process as the carbon doping and variable doping technologies are adopted; reducing a caesiated exhaustion region and increasing an escaping probability of photon-generated carriers as the variable doping comprehensively adopts zinc and carbon doping, and a caesiated surface adopts the zinc heavy doping; reducing a recombination rate of minority carriers of the interface as the interface of the window layer adopts the carbon light doping; and optimizing a high-performance photoelectric cathode as the carbon variable doping is adopted between an interface of the window layer and the zinc heavy doping layer to form a built-in electric field with good thermal stability.

Description

technical field [0001] The invention relates to a material variable doping structure which utilizes carbon doping and variable doping technology to enhance the short-wave response of a transmissive GaAs or InGaAs photocathode and has high thermal stability. The invention belongs to the technical field of photoelectric emission materials in visible and near-infrared bands. Background technique [0002] Image-intensified low-light night vision technology is a photoelectric imaging technology that allows people to directly observe blurred targets in low-light conditions through night-vision goggles with image intensifier tubes. As the core of image intensifier tubes, the development of photocathode has been developed from multi-alkali cathode materials to negative electron affinity (NEA) photocathode based on semiconductor materials. Compared with the multi-alkali cathode, the negative electron affinity photocathode has the advantages of high quantum efficiency, small dark emi...

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Problems solved by technology

[0005] 1) In order not to affect the cesium-oxygen activation during cesium oxidation, P-type GaAs is generally doped with Zn doping, and literature and experiments have shown that Zn is easier to diffuse at high temperatures, so the gradient or index based on Zn doping? In the photocathode process, there is a problem of doping distribution change after high-temperature hot pressing, high-temperature baking degassing, and high-temperature thermal cleaning, which greatly reduces or even disappears the built-in electric field strength.

[0006] 2) In general, GaAs on the cesium surface needs to be heavily doped to form a good cesium effect, but the current gradient doping and doping methods reported in the literature all set the GaAs on the cesium surface as a low-doping region

Since the surface affinity of GaAs is greatly reduced when cesium is oxidized, low-doped GaAs will form a thick cesium oxidized depletion region, which will affect the effective escape of photoelectrons.

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