Ammonia-free epitaxy of single-crystal InN using a plasma-integrated gas-injection module

Abstract

Group III nitride semiconductors are used for optical, high-frequency electronic, and power devices. In particular, indium nitride (InN) and In-rich indium gallium nitride (InGaN) are attractive materials for a wide range of carbon-neutral and post-5 G (5th generation mobile communication system) applications. However, the growth of high-quality bulk single crystals of both InN and In-rich InGaN cannot be ideally achieved owing to a mismatch between the low evaporation temperature of indium and the high temperature required to provide an adequate supply of reactive nitrogen species via the thermal decomposition of ammonia gas. In this study, we obtained a very-high-quality bulk InN material via epitaxial growth on a GaN template with the lowest dislocation density (∼3 × 109 cm–2) reported to date, and a narrow room-temperature full-width-at-half-maximum (∼0.1 eV) of the photoluminescence peak at 0.687 eV. These were achieved using a newly developed method obtained by combining microstrip-line microwave plasma irradiation with metal organic chemical vapor deposition. In this method, trimethylindium gas and pure nitrogen plasma (for producing a high density of nitrogen atoms) were supplied to a template independently, simultaneously, and continuously. We believe that the proposed procedure can serve as a standard guideline for non-toxic, low-energy-consumption, and low-cost manufacturing of numerous nitride-compound semiconductors.