Electrical studies in the microenvironment of dislocations in undoped high-resistivity GaAs

An improved point contact current topography (PCCT) technique of detecting electrical microscopic non-uniformities in high-resistivity semiconductors, especially in semi-insulating (SI) GaAs, is described. Using a B-implanted diamond tip, a local resolution high enough for the investigation of the microenvironment 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, force of the tip, etc.). A calibration of the point contact current to the resistivity allows quantitative profiling or topography of resistivity. For the first time results of the investigation of individual structural defects in SI GaAs are presented.