III-V compound semiconductors composed of III A -group electropositive elements (B, Al, Ga, In) combined with V A -group electronegative elements (N, P, As, Sb) have long been considered a promising material basis for a number of well-established commercial technologies, as well as for new advanced classes of electronic and optoelectronic devices . Examples include heterostructure and high-electron-mobility bipolar transistors, light-emitting diodes, diode lasers, photodetectors, and electro-optic modulators. The physical properties of the constituent materials are critical to the operating characteristics of these devices.