Solubility and Electrical Behavior of Zinc, Sulfur, Selenium, and Tellurium in Gallium Phosphide

Abstract

A thermal gradient technique was used to grow crystals at ∼1040°C from gallium solutions doped with zinc, sulfur, selenium, or tellurium. The solid solubilities of the donor impurities appear to vary linearly with the melt concentrations at the lower doping levels and with the square root of the melt concentration at higher doping levels, all in the extrinsic range. This behavior contrasts with that of zinc, for which the solid solubility varies only as the square root of the melt concentration as expected for a singly ionized acceptor dissolving in an extrinsic semiconductor. The excess donor or acceptor concentrations were significantly lower than the impurity concentrations at the higher doping levels.