On the effect of surface recombination on some properties of semiconductor devices

Abstract

A theoretical analysis of the influence of the surface recombination velocity of charge carriers on some static and dynamic parameters of planar semiconductor structures with a shallow p +-n junction is presented. The discussion is based on the solution of the continuity equation of charge carriers in a cylindrical base region for the case of a non-zero built-in electric field. Appropriate boundary conditions allow the use of the results presented here in the analysis of various devices of planar technology. The following were calculated as functions of the surface recombination velocity and the physical dimensions of the structure: the I( V) characteristic, the conductance (resistance) and the diffusion capacitance, the charge stored in the base region and the carrier transport coefficient. Typical plots are presented which can be helpful in evaluating the surface recombination effect on these parameters of semiconductor devices. It was found that the effect is strongest for structures with an n-n + interface. Using the formulae derived here the scatter of the electrical parameters of a device with the expected variation of surface recombination velocity can be evaluated for a given production line.