Effect of Si doping on the dislocation structure of GaN grown on the A-face of sapphire
- Materials Sciences Division, Lawrence Berkeley National Laboratory, MS 63-203, Berkeley, California 94720 (United States)
- Department of Material Science and Mineral Engineering, University of California, Berkeley, California 94720 (United States)
- Department of Electrical and Electronical Engineering, Meijo University, 1-501 Shiogamaguchi, Tempakuku-ku, Nagoya 468 (Japan)
Transmission electron microscopy, x-ray diffraction, low-temperature photoluminescence, and Raman spectroscopy were applied to study stress relaxation and the dislocation structure in a Si-doped GaN layer in comparison with an undoped layer grown under the same conditions by metalorganic vapor phase epitaxy on (11.0) Al{sub 2}O{sub 3}. Doping of the GaN by Si to a concentration of 3{times}10{sup 18} cm{sup {minus}3} was found to improve the layer quality. It decreases dislocation density from 5{times}10{sup 9} (undoped layer) to 7{times}10{sup 8} cm{sup {minus}2} and changes the dislocation arrangement toward a more random distribution. Both samples were shown to be under biaxial compressive stress which was slightly higher in the undoped layer. The stress results in a blue shift of the emission energy and {ital E}{sub 2} phonon peaks in the photoluminescence and Raman spectra. Thermal stress was partly relaxed by bending of threading dislocations into the basal plane. This leads to the formation of a three-dimensional dislocation network and a strain gradient along the {ital c} axis of the layer. {copyright} {ital 1996 American Institute of Physics.}
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 288770
- Journal Information:
- Applied Physics Letters, Vol. 69, Issue 7; Other Information: PBD: Aug 1996
- Country of Publication:
- United States
- Language:
- English
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