We report the results of studying the optical properties of cubic GaN thin films with photoluminescence and photoluminescence excitation spectroscopies. The films are deposited by plasma-assisted molecular beam epitaxy on GaAs (001) substrates, with and without intentional doping with carbon atoms (p-type doping). The evolution of the optical spectra of the C-doped samples is consistent with a picture in which carbon enters into N-vacancies at low concentrations, producing a marked improvement in the crystalline properties of the material. At higher concentrations it begins to form complexes, possibly due to interstitial occupation. The temperature dependence on the absorption edge of the doped material is also measured and is analyzed with standard theoretical models.
Bibliographical noteFunding Information:
Financial support from the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), both in the form of research grants (01/01067-4 and 98/12779-0) and of postdoctoral fellowships for some of the authors (J.R.L.F. and J.A.N.T.S.) is gratefully acknowledged. Funding from the Deutsche Forschungsgemeinschaft (DFG) is also acknowledged.
- Carbon doping
- Photoluminescence excitation