Optical and material properties of GaN/AlGaN quantum wells grown by atomic layer deposition

• Main Authors: Shih-Ching Mai, 麥仕青
• Other Authors: Hao-Chung Kuo
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/80839607990690552388

碩士 === 國立交通大學 === 顯示科技研究所 === 97 === In this thesis, we report the optical and material analysis of GaN/AlGaN quantum well using quasi AlGaN as a barrier layer, which is formed by AlN/GaN super-lattice layers grown with the technique of atomic layer deposition (ALD). In first part, the crystal quality were demonstrated by using PL spectra and HRTEM images which indicate the symmetry properties and good crystalline quality of the GaN/ALD-AlGaN QWs. Additionally, images of atomic force microscopy (AFM) revealed that the surface morphology of ALD-AlGaN are superior to those using conventional alloy AlGaN barrier. In second part, we investigate the optical properties by means of time-resolved photoluminescence system. According to energy dependence time-resolved PL measurement, we found slight localization in our ALD-QWs at low temperature. Detailed investigations of dynamical behaviors of Non-radiative and radiative recombination processes had been study through temperature dependent time-resolved photoluminescence (TRPL). It shows that quenched intensity of PL is significantly affected by non-radiative recombination at room temperature. Additionally, to investigate the physics behind quenched intensity, we performed the study of rate equation model and power dependent TRPL spectra of each sample at 15K. We concluded different effects which in turn dominate the mechanisms and carrier recombination in different excitation conditions. Finally, to check the internal quantum efficacy of our ALD-QWs, power dependent PL was experimentally used to estimate value of IQE. Compare to recent reports, the result appeals that our nanostructure has potential to fabricate high efficiency UV-emitting devices.