High-Temperature Atomic Layer Deposition of GaN on 1D Nanostructures

• Main Authors: Aaron J. Austin, Elena Echeverria, Phadindra Wagle, Punya Mainali, Derek Meyers, Ashish Kumar Gupta, Ritesh Sachan, S. Prassana, David N. McIlroy
• Format: Article
• Language: English
• Published: MDPI AG 2020-12-01
• Series: Nanomaterials
• Subjects: gallium nitride; atomic layer deposition; nanosprings; functional coatings; custom ALD reactor
• Online Access: https://www.mdpi.com/2079-4991/10/12/2434

Silica nanosprings (NS) were coated with gallium nitride (GaN) by high-temperature atomic layer deposition. The deposition temperature was 800 °C using trimethylgallium (TMG) as the Ga source and ammonia (NH₃) as the reactive nitrogen source. The growth of GaN on silica nanosprings was compared with deposition of GaN thin films to elucidate the growth properties. The effects of buffer layers of aluminum nitride (AlN) and aluminum oxide (Al₂O₃) on the stoichiometry, chemical bonding, and morphology of GaN thin films were determined with X-ray photoelectron spectroscopy (XPS), high-resolution x-ray diffraction (HRXRD), and atomic force microscopy (AFM). Scanning and transmission electron microscopy of coated silica nanosprings were compared with corresponding data for the GaN thin films. As grown, GaN on NS is conformal and amorphous. Upon introducing buffer layers of Al₂O₃ or AlN or combinations thereof, GaN is nanocrystalline with an average crystallite size of 11.5 ± 0.5 nm. The electrical properties of the GaN coated NS depends on whether or not a buffer layer is present and the choice of the buffer layer. In addition, the IV curves of GaN coated NS and the thin films (TF) with corresponding buffer layers, or lack thereof, show similar characteristic features, which supports the conclusion that atomic layer deposition (ALD) of GaN thin films with and without buffer layers translates to 1D nanostructures.