The role of carrier gas on the structural properties of carbon coated GaN

• Published in: Materials today communications Vol. 27; p. 102325
• Main Authors: Usman, Ibrahim B., Matsoso, Boitumelo J., Erasmus, Rudolph, Coville, Neil J., Wamwangi, Daniel M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2021
• Subjects: Argon; Carbon coating; Carrier gas; GaN; Nitrogen; Argon; Nitrogen; GaN; Carrier gas; Carbon coating
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2021.102325

Carrier gases in Chemical Vapor Deposition have been found to determine the deposition rate, and the physical and chemical properties of various coatings. In this work, the comparative effect of the carrier gases (Ar; N2) on the physico-chemical properties of carbon coated GaN submicron/micron samples is investigated. In this way, the distinctive momentum and thermal diffusivities of these carrier gases have yielded contrasting deposition rates owing to the varying thickness (∼7.5 nmAr and ∼11.4 nmN2) of the carbon coat on the GaN. Additionally, the powder X-ray diffraction patterns reveal formation of slightly smaller crystalline sizes for layers produced by Ar as a carrier gas (19.3 nm) in comparison to N2 (20.1 nm) in an acetylene ambient and at constant conditions. Our results further highlight that the use of two carrier gases leads to a red shift in the vibration modes of GaN with a higher interfacial strain at the GaN-C interface and defects (ID/IG ratios) when using Ar as the carrier gas. The presence of the Raman active modes associated with GaN also confirm that C coating on the GaN surface does not alter its structural integrity. Finally, suppression in intensity of the yellow luminescence peaks upon C-coating indicated improved surface electronic properties due to the presence of the anti-site (CN) defects. Thus, a carrier gas provides a new platform for intentionally tuning the properties of carbon coated GaN for future potential application in optoelectronic and sensing devices.