Improved Uniformity of Resistivity Distribution in LEC Semi-Insulating GaAs Produced by Annealing

Abstract
Two-dimensional distribution of resistivity in two-inch diameter crystals of LEC semi-insulating GaAs has been studied by the three-electrode guard method. Results are given in the form of a contour map for the wafers before and after annealing. Very significant fluctuations in resistivity on a 280 µm scale are observed for as-grown crystals, although the average of resistivity corresponds inversely to etch pit densities. The homogeneity of crystal grown at an 18 mm/h pulling rate, about two times faster than usual, is remarkably improved by annealing at 850°C for 20 minutes or longer.