Effects of post-growth thermal annealing on the indium aggregated structures in InGaN/GaN quantum wells
Journal
Journal of Crystal Growth
Journal Volume
242
Journal Issue
1-2
Pages
35-40
Date Issued
2002
Author(s)
Abstract
Size and distribution of indium-rich quantum dots (QDs) are important parameters for improving photon emission efficiency of InGaN/GaN quantum well (QW) structures. Our results showed that post-growth thermal annealing of such a sample with temperature ranging from 800°C to 900°C led to a better confinement of indium-rich clusters near InGaN QW layers. Transmission electron microcopy (TEM) and energy filter TEM results manifested that the sizes of indium-rich QDs were reduced with increasing annealing temperature. Also, the size homogeneity was improved. Quasi-regular arrays of indium-rich QDs embedded in InGaN QWs were observed in the sample of 900°C annealing. X-ray diffraction also showed the enhancement of InN relative intensity. Photoluminescence measurements revealed blue shifts of photon emission spectral peak, indicating stronger quantum confinement after thermal annealing. However, such a process of regular QD formation disappeared when annealing temperature was increased to 950°C. In this situation, coarsening of indium-rich clusters occurred and their distribution became irregular. © 2002 Elsevier Science B.V. All rights reserved.
SDGs
Type
journal article