Carbon doping by ion implantation and C 2H 6 gas in GaN: Rutherford backscattering/channeling, Raman scattering and photoluminescence studies

Abstract

Carbon related luminescence and lattice distortion in wurtzite GaN are studied. C atoms are intentionally doped into GaN by ion implantation method with energies of 200 or 400 keV and a fluence of 1 × 10 15 cm 2 and by a gas phase doping at 1273 K for 3 h under C 2H 6-gas flow. Lattice displacement of Ga atoms from 〈0 0 0 1〉 row in as-implanted samples is estimated to be of the magnitude of 0.013–0.014 nm by Rutherford backscattering (RBS)/channeling, while that in the gas phase doped sample is 0.008 nm, which is comparable to that of the unimplanted samples. The distortion in the implanted sample is not completely recovered. The Raman scattering intensity of E 2 phonon mode for the 200 keV is larger than that of the 400 keV, while that in the gas phase doping does not vary, supporting the RBS data. In all the doping methods, a prominent photoluminescence peak is observed at 3.293 eV with a small accompanied hump around 3.265 eV. These emissions are attributed to a band to C-acceptor and C donor–acceptor pair transitions, respectively, which suggests that binding energies of carbon acceptor and donor are ∼203 and ∼30 meV, respectively.