Synthesis of InGaN Nanowires: A review

Abstract

Nanowires constructed of indium gallium nitride (InGaN) are of great interest due to the wide range of stoichiometries made possible by the flexible composition of the alloy, allowing a range of observable properties in one material. This review article seeks to summarize key developments in the field of indium gallium nitride synthesis, observing breakthroughs in the fields of vapor beam epitaxy, molecular beam epitaxy, halide chemical vapor deposition, metal organic chemical vapor deposition, and vapor-liquid synthesis.

Introduction

The synthesis of nanowires containing nitrides of both indium and gallium has drawn interest in recent years for applications in light-emitting diodes, due to high levels of quantum efficiency, near the levels necessary for ultra-efficient solid state lighting(Phillips 2007). Equally important, if not moreso, is the wide range of bandgaps available with InGaN, made possible by varying the stoichiometric ratio within the alloy. Any InGaN nanowire is not an equal mixture of the three constituent elements, but rather InN and GaN alloyed, giving possible formulas of the format In\(_{x}\)Ga\(_{1-x}\)N, each having a slightly different bandgap, and thus bridging a very wide emissions spectrum. However, the relative paucity of studies concerning InGaN nanowires until recently(Growth Properties, an...) left researchers in the dark as to the complete properties possessed, or the best methods for efficient and precise synthesis.

Developments in the synthesis of these nanowires have naturally focused on these band gaps, as creating conditions that allow for the full spectrum of InGaN stoichiometries is critical to any major utilization of the material’s bandgap properties. This presented a major challenge to researchers of InGaN, as there is a significant difference in the lattice constants of InN and GaN(ODonnell 2001). However, this may have in fact spurred the development and investigation of InGaN nanowires, due to the unique advantage the nanowire structure has over other arrangements and growths of InGaN. In general, nanowires have shown to be remarkably free of the strain that accompanies alloys with large differences in lattice constant(Ertekin 2005), making nanowires more attractive for those seeking to fully utilize the potential of InGaN.