2 September 2014 Study on photoemission surface of varied doping GaN photocathode
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Proceedings Volume 9284, 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronics Materials and Devices for Sensing and Imaging; 92840H (2014) https://doi.org/10.1117/12.2070537
Event: 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies (AOMATT 2014), 2014, Harbin, China
Abstract
For varied doping GaN photocathode, from bulk to surface the doping concentrations are distributed from high to low. The varied doping GaN photocathode may produce directional inside electric field within the material, so the higher quantum efficiency can be obtained. The photoemission surface of varied doping GaN photocathode is very important to the high quantum efficiency, but the forming process of the surface state after Cs activation or Cs/O activation has been not known completely. Encircling the photoemission mechanism of varied GaN photocathode, considering the experiment phenomena during the activation and the successful activation results, the varied GaN photocathode surface model [GaN(Mg):Cs]:O-Cs after activation with cesium and oxygen was given. According to GaN photocathode activation process and the change of electronic affinity, the comparatively ideal NEA property can be achieved by Cs or Cs/O activation, and higher quantum efficiency can be obtained. The results show: The effective NEA characteristic of GaN can be gotten only by Cs. [GaN(Mg):Cs] dipoles form the first dipole layer, the positive end is toward the vacuum side. In the activation processing with Cs/O, the second dipole layer is formed by O-Cs dipoles, A O-Cs dipole includes one oxygen atom and two Cs atoms, and the positive end is also toward the vacuum side,thus the escape of electrons can be promoted.
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Jianliang Qiao, Ruijuan Du, Huan Ding, Youtang Gao, Benkang Chang, "Study on photoemission surface of varied doping GaN photocathode", Proc. SPIE 9284, 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronics Materials and Devices for Sensing and Imaging, 92840H (2 September 2014); doi: 10.1117/12.2070537; https://doi.org/10.1117/12.2070537
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