Researchers at the ANU node of TMOS have had their recent paper “Selective area growth of GaN nanowire: partial pressures and temperature as the key growth parameters” selected as the ACS Editors’ Choice (August 08, 2022).

The ACS Editors’ Choice features scientific articles that are deemed to have broad significance to the community. Less than 1% of articles published by ACS Journals are included in this collection. The articles are made free to access for a limited time in order to facilitate the proliferation of this high-impact research.

The paper, by authors Sonachand Adhikari, Mykhaylo Lysevych, Chennupati Jagadish, and Hark Hoe Tan, discusses the role of key parameters such as temperature and partial pressures of triethylgallium, NH3, H2 in the controlled growth of GaN nanostructures. Understanding the evolution of GaN nanostructure morphology with respect to these parameters provides a path to controlling and obtaining specific GaN nanostructures.

GaN is a semiconductor material that has become quite popular in the past few decades. It is a promising candidate for next-generation light emitting diodes, lasers, solar cells, transistors, electronic sensors, and biosensors. The challenge for GaN nanowire growth, however, has been the large number of variables and controlling those to achieve specific structures.

TMOS Chief Investigator Hark Hoe Tan and his team are overcoming this challenge by taking a unifying approach to metal organic chemical vapor deposition parameters. Rather than considering parameters such as flow rate of precursors and the carrier gas individually, they studied partial pressure as an overall unit of measurement that, combined with growth temperature, governed the regular and controllable growth of GaN nanostructures.

Lead author and PhD student Adhikari says “Uniform GaN nanostructure arrays will improve their optical properties and can be used as a platform for metasurface devices operating in the visible wavelength regime. We hope to see this work move the field of metamaterials forward significantly.

“I’m excited to see how this develops, especially in the field of holography and displays.”

For more information about this research, please contact connect@tmos.org.au

Selective Area Growth of GaN Nanowire: Partial Pressures and Temperature as the Key Growth Parameters

Sonachand Adhikari*, Mykhaylo Lysevych, Chennupati Jagadish, and Hark Hoe Tan

Crystal Growth & Design, 8th August 2022

Selective area growth of Ga-polar GaN nanowires by metal organic chemical vapor deposition provides a path to achieve arrays of uniform nanowires with controllable dimensions. A systematic investigation on the growth parameters of GaN nanowires demonstrates that although a low V/III ratio and low precursor flows are necessary, V/III ratio is not a sufficient parameter to determine the morphology of GaN nanowires. Partial pressures of the constituent gases, on the other hand, can be used as a single parameter, at a particular growth temperature, to explain the resulting morphology. By correlating the partial pressures of precursors and H2 in the carrier gas with the morphology of the nanowires, we can then determine the flow rates for precursors and hence the range of V/III ratios required for achieving the growth of GaN nanowires.