Mercury probeCU measurements on GaP

The electrical properties of GaP are examined using Schottky barrier capacitance techniques Mercury is used as the contacting metal and is successfully applied to homogeneously doped n-type material with carrier concentrations in the region of 3 × 1017 cm−3 and to zinc-diffused p-type material with non-homogeneous carrier distributions ranging from 4 × 1018 to 1.2 × 1019 cm−3. The atom concentration profiles of the diffused samples are determined using radiotracer analysis. A simple analogue system is devised to facilitate the CU measurements. Current-voltage measurements on the n-type material indicate that the n-criterion for capacitance profiling is not usefully applicable to this system, and lead to some conclusions regarding the ideality of diodes used for this technique. The acceptor concentrations of the p-type material are less than the corresponding atom concentrations, and possible causes of this discrepancy are discussed.