铯氧比对砷化镓光电阴极激活结果的影响

The Effect of Cs/O Activation Current Ratio on GaAs Photocathode

实验和理论分析结果表明,激活成功的砷化镓光电阴极的铯氧比存在一个最佳值.砷化镓光电阴极铯氧比的控制可通过调节激活过程中铯源和氧源的加热电流大小来实现.激活实验结果表明,铯氧电流比适中的样品,首次进氧时,光电流上升速度最快,激活后的阴极量子效率最高,稳定性好.当偏离这个比例,过大或过小时,光电流上升速度都会减慢,激活结果也比前者差.随着铯氧电流比的增大,铯氧交替的总次数随之减少.最佳铯氧电流比的调节应以首次进氧时光电流的上升速度最快为准,一旦确定后在整个铯氧交替过程中保持不变.

Experimental and theoretical analysis results show that there is an optimal Cs/O ratio for GaAs photocathode to activate successfully. In order to change Cs/O ratio of GaAs photocathode, the method applied is to regulate theheat currents of Cs resource and O resource in experiment. Activation experiment results show that the samples activated on appropriate Cs/O current ratio can achieve the optimal results, their photocurrent ascent rate is the largest during the first addition of O, quantum efficiency is the highest and stability is also very well. When deviation the appropriate Cs/O current ratio, activation experiment results are not as good as the former. Along with the increase of Cs/O current ratio, the total times of （Cs,O） alteration decrease. The Cs/O current ratio during the first （Cs, O） alternation should be regulated well, the Cs/O current ratio which can achieve the largest ascent rate is the optimal Cs/O current ratio. When regulated well the ratio should be maintained during activation process.