Diffusion and solid solubility of Zn in GaP at 850°C

Abstract

Zinc was diffused at 850°C from ternary sources containing 1–20 atom percent Zn and 0.5–1.0 atom percent P in Ga into n-type GaP grown by liquid phase epitaxy (LPE) and the liquid encapsulated Czochralski (LEC) process. Data on the surface concentration, and thereby the solid solubility of Zn as a function of the source composition, were obtained from65Zn radiotracer analysis and electrical measurements. At 850°C these values range from 8×l017 cm−3 for a 1 atom percent Zn to 5×1018 cm−3 for a 20 atom percent Zn concentration in the Ga/P/Zn ternary solution. These data are self-consistent, although they are somewhat lower than the previously reported values . Qualitatively, the results agree with recent thermodynamic calculations. The diffusion kinetics were found to be non-ideal as indicated by departures from a linear-square-root-of-time model and by reproducible changes in the junction depth following pre-diffusion heat treatments in different ambients.