Abstract
Combined experimental and computational efforts are focused to investigate the power-dependent micro-photoluminescence (APO properties of InxGal-xN/GaN multiple-quantum wells (MQWs). High-quality hexagonal InxGa1-xN/GaN[0001] MQWs were successfully grown using plasma-assisted molecular-beam epitaxy (PA-MBE), with multiplicity of 1, 3 and 5. Characterizations methods based on scanning tunneling electron microscopy (STEM) and PL indicated that each period is composed of 10 nm GaN barrier and 2.5 nm InxGa1-xN well with x <= 0.12. In power (ranging from 0.008 mW to 8 mW) dependent micro-photoluminescence (mu PL) measure at room temperature, blue shifts of about 11.11 nm, 11.94 nm and 14.94 nm were observed corresponding to the single-quantum well (1-QVV), 3-MQW, and 5-MQW, respectively. Experimental observations were further verified by simulations based on 3D tight-binding method using simple spa-basis set. The theoretical results show that larger blue-shift in 5-MQW sample to be attributed to higher bi-axial strain and interface-specific effects with a further increase of the hole well's (h-Well) depth, V-0, and increase in number of localized hole states within the h-Well. Furthermore, this study reveals role of bi-axial strain, well composition, and interface specific effects on the peculiar behaviors of valence-band offset (VBO) in InxGal-xN/GaN MQWs.