分析了半绝缘（ S I） gA AS 表面光伏的特点和公式.用表面光伏方法测量了不同砷压热处理 S I gA AS 单晶的双极扩散长度，用 1.1 μM 红外吸收法测量 E l2 浓度，并对测量结果作了分析和讨论.指出双极扩散长度 lA 是反映 S I gA AS 质量的一个重要电学参数.The features and the formulae of the surface photovoltage of semi insulating GaAs are analysed.The ambipolar diffusion length in undoped SI GaAs crystal by the thermal treatment in the different ambient of As atmosphere is measured by using the surface photovoltage method, and the EL2 concentration is measured by the 1.1 μm infrared absorption method,and the measured results are discussed.It is pointed out that the ambipolar diffusion length, L a is an important electrical parameter characterizing the quality of SI GaAs
