THE EVALUATION OF SURFACE RECOMBINATION VELOCITY FROM NORMAL-COLLECTOR GEOMETRY ELECTRON-BEAM-INDUCED CURRENT LINE SCANS

There are two well-known point source-based methods for the evaluation of the surface recombination velocity s from normal-collector geometry electron-beam-induced current (EBIC) line scans. The first was proposed by Jastrzebski, Lagowski, and Gates [Appl. Phys. Lett. 27, 537 (1975)], the second was by Watanabe, Actor, and Gates (WAG) [IEEE Trans. Electron Dev. ED-24, 1172 (1977)]. Scheer, Wilhelm, and Lewerenz [J. Appl. Phys. 66, 5412 (1989)] were unsuccessful in using the first method to extract s from their EBIC data. Hakimzadeh, Moller, and Bailey [J. Appl. Phys. 72, 2919 (1992)] applied the second method to evaluate a from their EBIC data without accounting for the mismatch between the theoretical requirement and the experimental condition relating to source size and electron penetration depth at which the WAG expression is to be evaluated. In this article these two methods are evaluated and their applicability to both point and extended-source data is examined quantitatively. Their limitations and shortcomings led us to suggest a way to extend the applicability of the WAG expression to include extended sources and to formulate two new Gaussian-source-based methods to evaluate the surface recombination velocity. A number of computed curves are provided to facilitate the application of these proposed new methods to GaAs and other semiconductors with diffusion lengths in the range of 0.5-3.0 mu m and (surfacerecombination velocity/diffusion coefficient) values in the range of 10(3)-10(6) cm(-1)