Depletion corrections in variable temperature Hall measurements

Abstract

The decrease in the measured Hall free-electron concentration with decreasing temperature near 300 K is often observed for thin high-purity GaAs layers. This has previously been interpreted as electron freezeout on deep donor sites. However, it can be quantitatively described by the decrease in carrier concentration per unit area associated with increasing surface and interface depletion region thicknesses. It is shown that when these depletion regions are included in the analysis of the Hall-effect data, the measured free-electron freezeout behavior can be accurately described by a simple shallow donor. If necessary, a deep donor may be included in the modeling. The results agree with the observed temperature variation of the capacitance-voltage (C-V) profiling data.