Theoretical and experimental study of charge carrier kinetics in crystalline silicon

A model simulating excess charge carrier kinetics in Si wafers was develope d taking into account space charge fields and surface recombination. This m odel was applied to experimental data obtained by contactless transient and frequency resolved photoconductivity measurements of silicon wafers with a ccumulation or depletion layers at the surface. It is shown that a surface accumulation layer has only a minor influence and surface recombination can be analyzed with a surface recombination velocity weakly depending on the excess carrier concentration. At low injection level a surface depletion la yer leads to a strongly nonlinear behavior of the photoconductivity due to excess charge carriers stored in the space charge region. The presence of t hese charge carriers is also revealed by the tail of the transient photocon ductivity signal characterized by a decay time longer than the volume lifet ime. At higher injection level the contribution of these charge carriers to the photoconductivity can be neglected and the data can be analyzed with t he (differential) surface recombination velocity. (C) 1999 American Institu te of Physics. [S0021-8979(99)02911-4].