High-quality GaN thin films are grown by rf-plasma assisted molecular beam epitaxy. The quality of the GaN epitaxial layer is significantly improved by using an intermediate-temperature GaN buffer layer (ITBL) in addition to a conventional 20-nm-thick low-temperature buffer layer. The GaN epitaxial layers demonstrate systematic improvements in the electron mobility increasing from 82 cm2V-1s-1, for films grown with just the low-temperature buffer layer, to about 380 cm2V-1s-1 for films grown with an ITBL of thickness 800 nm. The photoluminescence also indicates systematic improvements in the intensity and the full-width-half-maximum with the use of ITBL. Photoreflectance spectra are measured from the GaN films. Detailed analyses of the excitonic transition energy demonstrate that the residual strain relaxes rapidly with the use of ITBL, which is attributed to the observed improvements in the mobility and the PL spectra.
|Number of pages||3|
|Journal||Applied Physics A: Materials Science and Processing|
|Publication status||Published - Jan 1 2001|
ASJC Scopus subject areas
- Materials Science(all)