Pressure makes nanodiamonds, or nanopyramids, or nanowires

Tuesday 30 August 2022

Holograms made from arrays of tiny wires are a step closer after a new study of nanostructure fabrication revealed the tricks to making nanowires reliably.

Physicists at the Australian National University node of TMOS studied growth of gallium nitride nanostructures by chemical vapour techniques and found that partial pressures in the gas mix and growth temperature were key to controlling the type of nanostructures, such as nanowires, nanopyramids or nanodiamonds.

PhD student Sonachand Adhikari said understanding how to build gallium nitride structures could unlock new technologies.

“Gallium nitride is a promising candidate for next-generation light emitting diodes, lasers, solar cells, transistors, electronic sensors, and biosensors,” said Mr Adhikari, who was lead author of the team’s paper Selective area growth of GaN nanowire: partial pressures and temperature as the key growth parameters in the journal Crystal Growth and Design.

The paper was 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.

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.

“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,” Mr Adhikari said.

“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

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