Journal of Crystal Growth, Vol.435, 19-23, 2016
Molecular-beam epitaxy growth of dilute GaAsN alloys by surface nitridation
This paper presents the growth of GaAsN pseudo-alloys by a surface nitridation method that consisted of a repeated cycle of nitridation of the GaAs (001) surface, growth interruption and growth of a GaAs overlayer. Surface reconstruction during the nitridation process changed from (2 x 4) to (1 x 4) and (3 x 4) phases above 540 degrees C with the increase of nitridation time, resulting in a higher N compositions of the alloys. It was revealed that an excessive nitridation resulted in the degradation of the photoluminescence (PL) intensity. While the N composition slightly decreased with the interruption time, less impact appeared on their crystallinity characterized by PL measurement. As a result, the N composition was controllable between 1% and 5% by the combination of growth temperatures (460-600 degrees C) and thicknesses of the GaAs overlayer (2-8 monolayers; MLs). The thickness of the GaAs overlayer should be designed over 4 ML to form a flat surface for the next nitridation process. The integrated PL intensity of GaAs0.97N0.03 alloys was increased by 7 times compared to the one grown by conventional growth method (continuous supply), indicating the improved crystalline quality of the GaAsN alloys. (C) 2015 Elsevier B.V. All rights reserved.