“…In recent years the A' B"' C:' chalcopyrite semiconductors have been receiving considerable interest because they show promise for practical applications in nonlinear optics, light emitting diodes, photovoltaic optical detectors and solar cells (Shay and Wernick 1975, Smith 1975, Iseler et a1 1977, Wagner 1977, Bucher 1978, Pamplin et a1 1979, Neumann et a1 1981, Neumann 1983a. Also, a considerable amount of experimental and theoretical work has been done in order to gain a better understanding of the electronic, electrical and optical properties of this group of compounds (Shay and Wernick 1975, Pamplin etaZl979, Neumann etaZl981).…”