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Electroluminescence and photoluminescence from heavily carbon-doped GaAs

Electroluminescence (EL) and photoluminescence (PL) have been measured from thin layer structures of heavily carbon-doped GaAs film, with order 1020 cm-3 hole concentration, grown on semi-insulating GaAs substrate by metalorganic molecular beam epitaxy. The EL is detected only when the film contact is biased positively. The EL peak wavelengths at 80 K and 300 K occur at 900 nm and 950 nm respectively. The PL is measured at 3 K, 12 K, 80 K and 300 K, with peak wavelengths at 869.5 nm, 871.4 nm, 875.1 nm and 911.8 nm respectively. The EL spectra indicate that there are heterojunction interface states at about 50 meV below the conduction band. The PL of as-grown sample can be explained by band-to-band recombination in the heavily carbon-doped GaAs, and the PL of annealed sample arises from recombination centers, formed by CGa donors, in band gap.