Abstract: A method is disclosed for nondestructively profiling the uniformity of imperfection level densities in a semiconductor wafer. Resistance profiles from the wafer are obtained using an opaque spot filter and an optical filter. The difference between the resistance profiles is proportional to the density fluctuations of imperfections in the wafer material. By comparing the resistance profiles obtained using the opaque spot filter, and the optical filter an optically assisted imperfection profile (OAIP) of the imperfections in the wafer material is obtained.

Abstract: A method is disclosed for extrinsically gettering imperfections in a semi-insulating GaAs wafer. This is accomplished by subjecting the semi-insulating GaAs wafers to processing conditions which allow the imperfections to migrate toward a mechanically damaged surface region of the wafer. Migration occurs during a low temperature heat treatment over an extended time period. The GaAs wafer surface is damaged by a bead blasting treatment and subsequently heated to a temperature in the range of 400 to 600 degrees Celsius in a forming gas for a period between 12 to 120 hours. Significant improvements of the GaAs wafer qualities and performance of fabricated MESFET devices are achieved.