Quantum efficiency of GaN photocathode under different illumination

GaN samples are activated by Cs/O under illumination of deuterium lamp, 300 nm monochromatic light with power of 70 mu W and 300 nm monochromatic light with power of 35 mu W, respectively. Photocurrent is detected before activation under illumination of deuterium lamp. Quantum efficiency (QE) is tested after activation. The results indicate that GaN activated under 300 nm monochromatic light have higher QE than that under deuterium lamp, and no obvious difference is detected between different power 300 nm monochromatic light. The photocurrent before activation inhibits the adsorption of Cs on the GaN surface, which decrease the QE of GaN. (C) 2011 American Institute of Physics. [doi:10.1063/1.3614555]