N/P硅外延片的少子扩散长度测量

THE MEASUREMENT OF MINORITY CARRIER DIFFUSION LENGTH IN N LAYER OF N/P EPITAXIAL SILICON WAFER

本文提出了用N/P硅外延片的结光电压光谱响应确定N/P硅外延片中少子扩散长度的方法.导出了入射光强1和结光电压V、光吸收系数a的理论关系,其中包含了外延层和衬底少子扩散长度的信息.当N/P硅外延片表面有高温氧化生成的二氧化硅层时,样品的光电压取决于外延结的特性.可以用与表面光电压法同样的测试设备测得I～(?)曲线,从实验上求出了dI/d(a^(-1))/1(1/a)^(-1)值,由此值从理论图表中定出N型外延区中的空穴扩散长度.对一些N/P硅外延片进行了测试计算,结果表明本文提出的方法是合理的.

Using the photovoltaic spectral response of epitaxial P-N junction, the paper suggests a method of determining the minority carrier diffusion length in N layer of N/P epitaxial silicon wafer. The authors made a group of diagrams which contained the information of minority carrier diffusion lengths in the epitaxial layer and the substrate according to the theoretical analysis. When there is a thermal SiO2 thin film on the surface of the sample, the photovoltage of the sample depends on the characteristics of the epitaxial P-N junction. The incident photon intensity I versus reciprocal absorption coefficient 1/a curve is measured by the same method andsame apparatus as that of the SPV method, and the value of isevaluated on the I-1/a curve. Then the hole diffusion length in N epitaxial layer is calculated from the given diagrams. The experimental results show that the method is reasonable.