高温贮存对GaAs光电阴极光电发射性能影响研究

Effect of Storage at 70℃ on Photoemission Properties of GaAs Photocathode

为了研究高温贮存对GaAs光电阴极光电发射性能的影响,以2只GaAs光电阴极像增强器为研究对象,参照美军标MIL-STD-810F规定,对它们分别进行了70℃、48 h高温贮存实验。在实验过程中间隔一定时间测量一次其光电阴极灵敏度,随后利用Matllab软件和量子效率公式,计算了GaAs光电阴极参数,拟合了量子效率曲线。结果表明,GaAs光电阴极在70℃经过3～4 h贮存后,GaAs体材料与Cs-0表面层材料形成的光电发射层将达到稳定结构。研究成果为高性能GaAs光电阴极像增强器研制提供了技术支撑。

The impact ofthe storage of GaAs photocathode （at 70℃ and 15% humidityfor 48 h） ,on its emis- sion characteristics ,including the sensitivity and quantum efficiency ,was experimentally evaluated by measuring the sensitivity every hour, theoretically analyzed by data-fitting and numerically calculated with software Matlab. The re- suits show that thestorage at 70℃ of GaAs photocathode strongly affects the sensitivity and quantum efficiency. For example, as the storage time increased, the sensitivity rapidly decreased in the 1 st hour, and then changed in a rapid- increase and slow-decrease mode, with a decrease by about 20% ; the quantum efficiency in 500 - 900 nm range markedly decreased, and the decrease from 12 to 24 h was bigger than that from 0 to 12 h. Storage at 70℃ for 3 4 h stabilized the electronic structures at the interface of the Cs-O surface layer and the GaAs substrate. Possible mechanisms responsible for the observations were also tentatively discussed in a thought-provoking way.