Characterization of high-quality MBE-grown GaN films on intermediate-temperature buffer layers |
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Authors: | CF Zhu WK Fong BH Leung C Surya |
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Institution: | (1) Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong (Fax: +852/2362-8439, E-mail: zhucf@eie.polyu.edu.hk; ensurya@polyu.edu.hk), HK |
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Abstract: | 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 cm2 V-1 s-1, for films grown with just the low-temperature buffer layer, to about 380 cm2 V-1 s-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.
Received: 30 November 2000 / Accepted: 4 December 2000 / Published online: 9 February 2001 |
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Keywords: | PACS: 81 15 Hi 73 61 Ey 78 66 Ed |
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