An improved point contact current topographic technique for detecting microscopic electrical non-uniformities in high-resistivity semiconductors (especially semi-insulating GaAs) was described. By using a B-implanted diamond tip, a local resolution which was high enough for investigating the micro-environment of single dislocations could be achieved. The force dependence of the point contact current, I¯V characteristics and current profiles were used to choose the optimal measuring conditions (bias voltage, tip force, etc). Calibrating the point contact current against the resistivity permitted the quantitative profiling of the resistivity and, for the first time, an investigation of individual structural defects in semi-insulating GaAs could be conducted.

Electrical Studies in the Microenvironment of Dislocations in Undoped High-Resistivity GaAs. W.Siegel, A.Sidelnicov, G.Kühnel: Materials Science and Engineering B, 2002, 91-92, 403-6