Epitaxial growth of high In-content In0.41Ga0.59N/GaN heterostructure on (11–20) Al2O3 substrate

Abstract

Growth characteristics of high Indium content InGaN/GaN heterostructure on a-plane (112¯0) sapphire substrate by plasma assisted molecular beam epitaxy have been investigated in detail. The structural analysis is carried out by high-resolution X-ray diffraction measurements. A reduction in the lattice constant by 0.15% confirms the highly crystalline nature of the grown GaN film. Field Emission Scanning Electron Microscopy measurements divulged smooth morphology with less hexagonally pitted GaN surface. This high quality MBE grown GaN on (112¯0) sapphire is utilized as a template to grow InGaN film with high indium composition (41%). The elemental distribution and thickness of the grown film is ascertained by Secondary Ion Mass Spectroscopy which demonstrates a sharp interface between the grown structure. The photoluminescence emission spectrum shows a sharp near band edge emission of GaN at 3.42 eV along with a broad band emission related to defects and near band edge emission of InGaN (1.9 ± 0.05 eV) at room temperature. This study provides a new insight into the structural quality of In-rich InGaN/GaN based heterostructures on a-plane sapphire, which could be useful to develop highly-efficient nitride solar cell devices.