The defect concentration in thin GaN layers was estimated by means of positron annihilation spectroscopy. Positron lifetime and Doppler broadening of the annihilation radiation were used. A comparative study of GaN films grown with different techniques was performed. Specific attention has been given to the new low energy plasma enhanced vapor phase epitaxy (LEPEVPE) growth technique. A very high Ga vacancy density (1019 cm−3) was found in a thin GaN layer directly grown by LEPEVPE on a sapphire substrate. However, when a GaN substrate (commercial sample grown by Metal Organic Vapor Phase Epitaxy) is used as a template for LEPEVPE deposition, the vacancy density of the film is low (about 1016 cm−3). This fact provides evidences that the LEPEVPE technique is able to produce high quality GaN layers.
Characterization of vacancy-type defects in heteroepitaxial GaN grown by low-energy plasma-enhanced vapor phase epitaxy
A. Calloni, R. Ferragut, A. Dupasquier, H. von Känel, A. Guiller, A. Rutz, L. Ravelli, W. Egger; Characterization of vacancy-type defects in heteroepitaxial GaN grown by low-energy plasma-enhanced vapor phase epitaxy. J. Appl. Phys. 15 July 2012; 112 (2): 024510. https://doi.org/10.1063/1.4737402
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