GaAs光阴极激活稳定性研究

Stability of GaAs photocathode activation

为了提高Cs-O激活后GaAs光阴极的稳定性,延长像管的使用寿命,从Cs-O激活方面着手进行研究,寻找解决途径。改变GaAs光阴极激活中的Cs过量,并在线监测真空环境下光电流的变化情况,寻找激活对GaAs光阴极稳定性的影响因素。分别进行3组5种比例的激活实验,在光电流下降至Cs峰峰值90%、70%、50%、30%和10%时给O进行交替激活。激活结束后,在低于1×10-8Pa的真空环境下在线监控30 min内的光电流,发现过Cs90%、70%、50%激活的光阴极稳定性好,过Cs30%次之,过Cs10%相对最差。结果表明:GaAs光阴极Cs-O激活时,Cs量越多,表面势垒的建构越完整,光阴极的稳定性就越好,对改善GaAs光阴极稳定性,延长使用寿命具有重要意义。

In order to improve the stability of GaAs photocathodes after Cs-O activation and prolong the lifetime of image tubes, Cs-O activation was studied to find appropriate solutions. Combined changing the excess amount of Cs in activation with online monitoring of photocurrent in UHV, the factors influencing the stability of GaAs photocathode were investigated. Three groups of experiments were carried out, and same five kinds of Cs excess proportion were included in each group. After the photocurrent decreased to 90%, 70%, 50%, 30% and 10% of the Cs peak value, oxygen was introduced for alternate activation. It was found that the stability of photocathodes with Cs excess of 90%, 70% and 50% was better and the stability of 30% or 10% was worse by online monitoring of photocurrent during 30 min in UHV of less than 1＆#215;10-8 Pa. The results indicate that with more Cs amount in Cs-O activation the construction of surface barrier is more integrated and the stability of photocathode is better. These results are important for improving the stability of GaAs photocathodes and prolonging the lifetime of image tubes.