用微波光电导谱研究半导体薄片的少子扩散长度和表面复合速度

Study on Surface Recombination Velocity and Diffusion Length in Semiconductors by Microwave Photoconductivity Spectrum

当半导体薄片同时受到微波和光照射时,通过样品的微波传输系数与光的波长有关,当光的波长连续地变化时,微波传输系数也连续地变化。本文分析了在半导体薄片中的少子扩散长度、少子寿命及表面复合速度与上述微波传输系数的变化△T之间的关系,并通过测量半导体薄片的微波光电导谱计算这些参数。研究表明,可以从微波光电导谱中的△T的峰值位置直接算出少子扩散长度。这是一种无接触、无损伤的快速测试方法,测试区域是直径为3mm的一个圆斑,样品可以在测试台上自由移动。本方法的测试结果与其它方法所得的结果是较为一致的。

When semiconductor wafer is illuminated by microwave and light, the microwave transmission coefficient (MTC) is related to the wavelength of light.We have theoretically analysised the relationship among the MTC, the diffusion length, the lifetime of minority carrier and the surface recombination velocity.It is possible to obtain all these parameters through the microwave photoconductivity spectrum (MPCS).We have measured the MTC at different light wavelength using contactless method. The measuring area is a circular spot of about 7mm^2.