ABSTRACT
Gallium phosphide (GaP) crystals are optically transparent and slightly tinted in spectrum from lemon-yellow to amber-orange depending on dopant type and concentration. Epitaxial layers of GaP grown by any common method such as liquid phase epitaxy, vapour phase epitaxy, metal-organic chemical vapour deposition and molecular beam epitaxy have the best quality. GaP has been the model semiconductor for studying different mechanisms of luminescence for a long time. Determined by vertical optical transitions, fundamental absorption edge and edge luminescence smoothly shift with composition of direct band GaP alloys. Impurity properties and electrical conductivity are analogous to those in the corresponding ternary alloys. Spontaneous long-range ordering may occur in quaternary alloys grown under certain conditions.
