Cs-activation-free heterojunction type GaN negative electron affinity photoelectric cathode

Abstract

The invention discloses a Cs-activation-free heterojunction type GaN negative electron affinity (NEA) photoelectric cathode which comprises a substrate, a GaN / AlN superlattice buffer layer or AlN buffer layer growing on the substrate, a p-Alx1Ga1-x1N light absorption layer growing on the GaN / AlN superlattice buffer layer or AlN buffer layer, an n<+>-Alx2Ga1-x2N cap layer growing on the p-Alx1Ga1-x1N light absorption layer, and electrodes made on the surface edge of the n<+>-Alx2Ga1-x2N cap layer and the side surface of a multilayer material, wherein x1 is more than 0 and less than 1, and X2 is more than 0 and less than 1. According to the invention, an NEA characteristic of a cathode can be achieved without activating Cs, and the advantages of reducing the difficulty of making a high-quality NEA cathode and prolonging the service life of the cathode without maintaining an ultrahigh vacuum environment are achieved.

Description

technical field [0001] The invention belongs to the technical field of semiconductor photoelectric emission, in particular to a heterojunction GaN negative electron affinity photocathode without Cs activation. Background technique [0002] Ultraviolet detection technology has a wide range of applications in the fields of early warning, communication, aerospace, medicine, biology and environmental monitoring. The current ultraviolet detectors mainly include solid-state ultraviolet detectors and vacuum-type ultraviolet photocathode detectors. Solid-state ultraviolet detectors mainly include pn junction type, PIN type, Schottky barrier type and MSM type, which have the advantages of small size, light weight, adjustable detection wavelength, simple working circuit, and no need for high voltage operation. UV-enhanced silicon photodiodes are representative of solid-state UV detectors, but their response to visible light limits their application in the field of UV detection. Wit...

AI Technical Summary

Problems solved by technology

However, it is difficult to precisely control the flow of Cs during the fabrication of traditional NEA cathodes, which increases the difficulty of making high-quality NEA cathodes.

In addition, the chemical activity of Cs is very high, and it is very easy to react with other substances, so the cathode after Cs activation needs to be maintained in an ultra-high vacuum environment, which also limits its application to a certain extent.

Although the bond energy of GaN adsorbing Cs is higher than that of GaAs, due to the influence of ultraviolet radiation and feedback positive ions on the cathode during work, Cs atoms are still easy to desorb, resulting in a decrease in cathode sensitivity and shortening the service life of the device.

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