The electrical, structural, and optical properties of GaAs grown by metalorganic chemical-vapor deposition using CCl4 have been studied and the growth rate reduction by CCl4 under various growth conditions has been investigated. Hole concentrations ranging from 2×1016 to 1.8×1020 cm−3 have been obtained by varying V/III ratio and growth temperature. From Hall, x-ray, and low-temperature photoluminescence measurements, a low compensation is ensured. A growth rate reduction up to 50% has been observed. The dependence of the growth rate reduction on the growth temperature, the V/III ratio, and the CCl4 mole fraction was investigated. It is believed that the growth rate reduction is caused not by etching of solid GaAs but by reduction of Ga species through the formation of GaCl in gas phase.

Carbon-doped GaAs epilayers with concentrations as high as 1.8×1020 cm−3 were studied by photoluminescence (PL) spectroscopy. A shoulder is observed at 1.495 eV in 17 K PL spectrum of the heavily C-doped sample grown on semi-insulating substrate. But the shoulder occurs at different energies when the substrate conductivity is changed. The shoulder is found to originate from the substrate luminescence. Identifying the origin of the shoulder, the true Fermi level of p+-GaAs is determined and the band gap narrowing due to heavy doping is quantified.