Doping gradients in layers of gallium phosphide grown by liquid epitaxy

Abstract

Layers of epitaxial gallium phosphide doped with either tellurium, sulphur or zinc over the range 10 '~ to 10 '8 cm-2 have been grown from gallium solution using a vertical dipping system. These layers of thickness 60 to 80 /~m have been produced on the (1 00) and (111)B faces of gallium phosphide single crystal substrates at high growth rates. Doping gradients have been investigated by a Schottky barrier technique over an angle lapped region of the grown slice, measuring the capacitance voltage characteristics of the individual barriers. Significant changes in doping level have been observed throughout the thickness of the layers and these are related to the variation of distribution coefficient, the losses of impurity from the system and the presence of competing background impurity systems.

Control of Zn Doping for Growth of InP pn Junction by Liquid Phase Epitaxy

“…When Zn is chosen as p-type dopant in the LPE growth, however, one should pay attention to its high vapor pressure as well as to the relatively high diffusion coefficient in the semiconductor bulk at the growth temperature. The evaporation of Zn in the Ga melt during GaP growth has resulted in the carrier density profile decreasing toward the epitaxial layer surface (4). The misplacement of the pn junction observed in the GaAs (5) and the InP (2) homojunctions and the InP=Inl-xGax-Asl-yPy heterojunction ( 6) is considered to be attributable to either the Zn diffusion during the p +-type layer deposition or to the cross-contamination of melts caused by the Zn evaporation.…”