Numerical Calculation and Experimental Reserch of Ultraviolet Photoelectron Yield Spectrum of AlGaN Photocathode Material

AlGaN photocathode can realize the “solar-blind” ultraviolet detection function with a wavelength response range below 280 nm due to its adjustable Al component. Based on the classical three-step emission theory and combined with the solid band theory, the theoretical models of ultraviolet photoelectron yield of reflective and transmissive photocathodes were established and the expressions were derived. The ultraviolet photoelectron yield spectra of AlGaN photocathode in two working modes were calculated and plotted and compared with the experimental results in the literature. The influence of some factors on the ultraviolet photoelectron yield of AlGaN photocathode was analyzed. At the same time, the ultraviolet photoelectron yield spectrum experimental test of single-layer AI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.27</inf>Ga<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.73</inf>N crystal material was completed by simulating the emission layer of reflective AlGaN photocathode using ultraviolet photoelectron spectrum analyzer. The test results show that in the wavelength range of 220~310 nm, the ultraviolet photoelectron yield of single-layer AI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.27</inf>Ga<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.73</inf>N crystal material is about 4%-6%, and it begins to drop sharply after the incident light wavelength reaches 310 nm.