Measurement of the Minority Carrier Diffusion Length in Thin Wafers of Semiconductor Crystals

Abstract

A method for the measurement of the minority carrier diffusion length and the estimation of the surface recombination rate in thin silicon wafers is described. The method is based on the measurement of the photocurrent flowing through a wafer with identical shallow-lying p–n junctions occupying a sufficiently large area on both sides of the wafer (a phototransistor with a disrupted base). Measurements are performed at two polarities of the bias voltage and two diameters of the radiation beam. Practical recommendations concerning the implementation of this method are given.