Using the first-principles method based on the density functional theory（DFT）, the work function of seven different Ga N（0001） e1 × 1T surface models is calculated. The calculation results show that the optim...Using the first-principles method based on the density functional theory（DFT）, the work function of seven different Ga N（0001） e1 × 1T surface models is calculated. The calculation results show that the optimal ratio of Cs to O for activation is between 3∶1 and 4∶1. Then, Cs/O activation and stability testing experiments on reflection-mode negative electron affinity Ga N photocathodes are performed. The surface model [Ga N（Mg）： Cs]Cs-O after being activated with cesium and oxygen is used. The experiment results illustrate that the adsorption of O contained in the residual gas increases the surface potential barrier and the reduction of the effective dipole quantity is the basic cause of the quantum efficiency decay.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 61308089 and 61440065)the Public Technology Applied Research Project of Zhejiang Province (No. 2013C31068)+1 种基金the Applied Research Project of Zhejiang Provincial Education Department (Nos. Y201432598 and 201328587)the China Postdoctoral Science Foundation funded project (No. 2014M551596)
文摘Using the first-principles method based on the density functional theory（DFT）, the work function of seven different Ga N（0001） e1 × 1T surface models is calculated. The calculation results show that the optimal ratio of Cs to O for activation is between 3∶1 and 4∶1. Then, Cs/O activation and stability testing experiments on reflection-mode negative electron affinity Ga N photocathodes are performed. The surface model [Ga N（Mg）： Cs]Cs-O after being activated with cesium and oxygen is used. The experiment results illustrate that the adsorption of O contained in the residual gas increases the surface potential barrier and the reduction of the effective dipole quantity is the basic cause of the quantum efficiency decay.
