Tuning the structure and electro-optical properties of α-Cr2O3 films by heat treatment/La doping for optoelectronic applications

Abstract

Controlling the physicochemical features of chromium sesquioxide α-Cr2O3 (chromia) films is essential to widening their utilization. This work investigates the influence of heat treatment (HT) and La doping on the physical characteristics of chromia films spin-deposited on glass. X-ray diffraction/Fourier transform infrared spectroscopy and field-emission transmission electron microscopy techniques reveal that the crystallinity, size, and modes of vibration in chromia (eskolaite phase) can be tuned by HT and La doping. Energy-dispersive X-ray analysis confirms the presence of La in the hexagonal chromia films. All films display high transmittance (T%) and improved absorption indices in the UV and near-infrared regions. The films’ reflection and refractive indices are in the range of 6–15% and 1.77–1.97, respectively. The impact of HT and La content on the optical band gap, lattice dielectric constant, and electron-effective mass is reported. The current–voltage characteristic curves reveal the Ohmic resistance, and the films’ sheet resistance demonstrates sensitivity to HT and La content. The findings of this study illustrate the possible development of optoelectronic devices and chromia-based IR sensors.

Keywords

• α-cr2o3
• band gap engineering
• optical constants
• la doping
• i–v characteristics