ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Mist CVD-based growth of crystalline alpha chromium oxide (α-Cr₂O₃) on c-plane sapphire substrate with chromium acetylacetonate as a precursor

Md Sadullah, Syed Mohd Hussain, and Kunal Ghosh

School of Computing and Electrical Engineering, IIT Mandi, Kamand, India

E-mail: kunal@iitmandi.ac.in

Received: 7 April 2023  Accepted: 7 June 2023

Abstract:

α-Cr₂O₃ is used as a buffer layer for the growth of α-Ga₂O₃ on sapphire for power devices. Presently, the growth of crystalline corundum-structured metal oxides layers, except for α-Cr₂O₃, is performed with metal acetylacetonates. This article investigates the development of a crystalline α-Cr₂O₃ thin films on c-plane sapphire with chromium acetylacetonate (CrAc) as precursor over a wide temperature range varying from 400 to 550 °C. The temperature range not only ensures the compatibility of the process with α-Ga₂O₃ technology but also satisfies the requirement that the window is large enough to adequately optimize the quality of crystalline α-Cr₂O₃ thin film. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were performed to analyse the quality of the crystalline α-Cr₂O₃ layer. The XPS result showed that the ratio of different oxidation states of α-Cr₂O₃ changes with deposition temperature. An optimal deposition temperature at 500 °C with the molarity of CrAc being 0.05 M is achieved for better quality α-Cr₂O₃ thin film deposition. Thin film of α-Cr₂O₃ of thickness 530.5 nm has been deposited at optimal condition with a deposition rate of 35.37 nm/min and has a crystallite size of 31.21 nm and root mean square value of surface roughness of 0.647 nm.

Keywords: Thin film; Mist CVD; Chromium oxide; Sapphire; Corundum structure; XPS

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-02920-2

Chemical Papers 77 (10) 6041–6052 (2023)