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为探索砷化镓光阴极的光电灵敏度的影响因素 ,利用X射线光电子能谱、二次离子质谱和电化学方法测试和分析了国内和国外GaAs光阴极材料GaAs/AlGaAs的C ,O含量和空穴浓度分布。实验发现 ,国内的材料在GaAs/AlGaAs界面及AlGaAs层的O含量分别为 7 6 %和 10 6 % ,C浓度分别为 5 2×10 18atoms/cm3和 1 0× 10 19atoms/cm3,而国外的材料的O含量相应为 1 0 %和 1 5%。国内的材料GaAs和AlGaAs层的空穴浓度分别为 7× 10 18～ 4× 10 19cm- 3和 8× 10 17cm- 3,而国外材料的相应值分别为 (1 8～ 2 0 )× 10 19cm- 3和 5× 10 18cm- 3。分析认为 ,层中及界面的C ,O杂质偏高和空穴浓度分布不尽合理使光电子扩散长度减小 ,后界面复合增大 ,导致了光电灵敏度下降。
In order to explore the influence factors of photoelectric sensitivity of gallium arsenide photocathode, the content of C, O and GaAs / AlGaAs in domestic and foreign GaAs photocathode were tested and analyzed by X-ray photoelectron spectroscopy, secondary ion mass spectrometry and electrochemical method Point concentration distribution. The experimental results show that the O content of GaAs / AlGaAs interface and AlGaAs layer in domestic materials are 76% and 106% respectively, and the C concentrations are 5 2 × 10 18 atoms / cm 3 and 10 × 10 19 atoms / cm 3, respectively. The O content of the material is 10% and 15% respectively. The hole concentrations of GaAs and AlGaAs layers in China are 7 × 10 18 ~ 4 × 10 19 cm -3 and 8 × 10 17 cm -3, respectively, while the corresponding values for foreign materials are (18 ~ 20) × 10 19 cm - 3 and 5 x 10 18 cm-3. The analysis shows that the C and O impurities in the layer and interface are not high and the hole concentration distribution is not reasonable, which makes the photoelectron diffusion length decrease and the interface recombination increases, which leads to the decrease of photoelectric sensitivity.