Ageing phenomena and determination of the optical self absorption coefficient in PN junction
作者:S. Guermazi、Y. Mlik、B. El Jani、C. Grill
DOI:10.1051/epjap:2001193
日期:2001.10
We have developed a model for the calculation of the induced current due to an electron beam with an extended generation profile. The analytical expression of the electron beam induced current (EBIC) is obtained by solving the steady-state continuity equation using the Green function method. In the case of a sulphur doped (Ga0.7Al0.3As:N+/Ga0.7Al0.3As:P) sample prepared by metalorganic vapour phase epitaxy (MOVPE) method, the experimental current profile, measured by SEM enabled us to calculate the diffusion length of the minority carriers (Lp = 1 μm in the N region and Ln = 1.80 μm in the P region of the ternary sample). Far from the depletion layer, the experimental current profile measured provided us the optical self absorption coefficient of this sample: ap = 1.483 μm−1 in the N region and an = 0.167 μm−1 in the P region. According to our EBIC model, the width of the depletion layer of this sample is about 0.8 μm, while at elaboration of the sample, 10 years ago, the width of the depletion layer deduced from the characteristic curve I(V) was about 300−400 Å. This widening of the depletion layer is due to the ageing of the diode.
我们开发了一种模型用于计算由于具有扩展生成特征的电子束所引起的感应电流。通过使用格林函数方法解决稳态连续性方程,获得了电子束感应电流(EBIC)的解析表达式。在通过金属有机蒸气相外延(MOVPE)方法制备的硫掺杂(Ga0.7Al0.3As:N+/Ga0.7Al0.3As:P)样品中,通过扫描电子显微镜(SEM)测量的实验电流分布使我们能够计算出少数载流子的扩散长度(在N区为Lp = 1 μm,在P区为Ln = 1.80 μm)。在远离耗尽层的地方,测量到的实验电流分布为我们提供了该样品的光学自吸收系数:在N区为ap = 1.483 μm−1,在P区为an = 0.167 μm−1。根据我们的EBIC模型,该样品的耗尽层宽度约为0.8 μm,而在10年前样品制备时,从特征曲线I(V)中推导出的耗尽层宽度约为300−400 Å。耗尽层的扩大是由于二极管的老化。