OMVPE growth and characterization of carbon doped InAs

Carbon-doped InAs samples grown by organometallic vapor phase epitaxy were studied by Raman and IR spectroscopy. Local vibrational modes (LVMs) related to isolated substitutional carbon acceptors, carbon acceptor-hydrogen complexes, and dicarbon centers were detected in samples doped with two isotopes of carbon. Energies of the observed carbon-hydrogen modes are in close agreement with carbon acceptor-hydrogen modes in GaAs and InP, and are consistent with hydrogen occupying a bond-center position in the complex. No sign of substitutional carbon donors was observed. N-type conductivity of carbon-doped InAs was explained by the presence of dicarbon centers that are believed to be deep donors. The stretch mode of this complex was detected at 1832 cm-1 by Raman spectroscopy in as-grown and annealed samples. Annealing measurements performed on heavily carbon-doped InAs samples confirmed that the n-type conductivity observed for this material is due to the formation of dicarbon defects. The structural, electrical, and optical properties of n-type carbon-doped InAs samples annealed at temperatures of 400°C and higher were studied using Raman and infrared spectroscopy, and X-ray diffraction. Based on the expected energy level of dicarbon donors in GaAs, we predicted that the di- carbon defects in InAs should introduce a resonant level close to or slightly above the conduction band minimum.