超高真空条件下NEAⅢ-Ⅴ族半导体光电阴极的工艺与性能的研究

INVESTIGATION OF THE ACTIVATION TECHNIQUE AND THE CHARACTERISTICS OF NEA Ⅲ-Ⅴ SEMICONDUCTOR PHOTOCATHODES

介绍对GaAs及1.25μm InGaAsPⅢ-Ⅴ族半导体光电阴极的激活工艺及其性能的初步研究结果。全部采用国产超高真空系统,真空度优于8×10^(-8)Pa。在真空系统中激活的GaAs(Cs,O)光电阴极的积分灵敏度约为550μA/lm,InGaAsP(Cs,O)光电阴极在1.06μm处的量子效率为0.4%。用2.06μm波长(禁带宽度E_(?)=1.25μm)、ns量级脉宽的Er,Tm,Ho:YLF激光作激发源在GaAs(Cs,O)光电阴极中实现了三光子光电发射。在液氮温度下测得的数据与室温下测得的数据相吻合,证明热发射相对于三光子光电发射可以忽略。

We report our investigation into the technique of the activation of NEA Ⅲ-Ⅴ semiconductor photocathodes and their photoemission characteristics. Firstly, the UHV system used is explained and the pressure is lower than 8×10^(-8)Pa. Then, the activation procedures are given. The sensitivity of 550μA/lm of a GaAs(Cs,O) photocathode is obtained. The InGaAsP cathode (E_(?)=1.25μm) results in a quantum efficiency of 0.4% at a wavelength of 1.06μm. Three-photon photoemisston effect of the GaAs(Cs,O) photocathode, under the irradiation of 2.06μm wavelength, ns pulse duration Er, Tm, Ho: YLF laser, is investigated. The data measured at liquid nitrogen temperature fits into the data at room theperature demonstrate that the thermal emission maybe negligible comparing to the three-photon photoemission.