Marked improvements in electrical and optical properties for MOVPE InN annealed at a low temperature (300 °C) in O2 atmosphere

摘要

We have found that the material quality of MOVPE InN can be markedly improved after the annealing in the air at around 300 °C. By the annealing in the air, carrier concentration is reduced by about one order of magnitude. In accordance with the carrier reduction, PL intensity is increased and PL peak energy is shifted to the lower energy side by about 0.06 eV for the film annealed for 3 h. The reduction of carrier concentration is also conformed by the shift of LO phonon-plasmon coupled mode in the Raman spectrum. The FWHM of the E_2 (high) mode is decreased, indicating that the crystalline quality is slightly improved by the annealing. Since the FWHM of X-ray rocking curve is not changed after the annealing, the improvement by the annealing is concluded not to be in macroscopic scale but microscopic scale. No improvements are found for the samples annealed in the N_2 flow. No data that show the chemical oxidation of InN are also found.