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

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.