混晶GaAs_(1-x)P_x禁带中央附近能级的研究

Study of the Mid-gap Level in GaAs_(1-x)P_x

用双光源光电容法研究了混晶 GaAs_(1-x)P_x(x=0.65和0.85)中禁带中央附近深中心的特性,发现所测 x=0.65和0.85的GaAs_(1-x)P_x样品中均存在一个呈空穴陷阱的深中心,其光阀值能量分别为 0.95 eV和 0.97 eV,光电容瞬态谱具有非单指数性;且在同一波长的光激发下,非单指数性随激发光强度的增大而增强。对这一深能级中心的结构及其激发过程进行了分析和讨论,提出一种多能级耦合的缺陷中心模型并用二步激发过程解释了实验结果。

The characteristics of the deep level which is near mid-gap in , 0.85)are studied by double light source photocapacitance thechnique. A deep level centre which shows the hoie trap behaviour is found in GaAs1-xPx(x=O.65, 0.85) sample. The optical threshold energy of this hole trap centre is 0.95 eV and 0.97 eV for x=0.65 and x=O.S5, respectively, and their transient photocapacitance spectra are not single-exponential. Under exciting of light which wavelength is not changed, with the increase of light intensity the non-single-exponential behaviour of photocapacitance transient get more obvious, The level structure of the trap centre is discussed and their excited processes are analysed. The exprimental results are explained by a two-step excitation model based on the assumption of multiple level coupling centre model.