Insights into the properties and possible bonding states of radiofrequency-magnetron-sputtered indium tin oxide thin films acquired using ultraviolet–visible spectroscopy data for cost-effective material characterization

Abstract

Indium tin oxide (Sn-doped In2O3) is an optical material that is widely utilized in designing modern optoelectronic devices. To demonstrate the efficiency of ultraviolet–visible spectroscopy as a primary analysis tool for thin-film characterization, Sn-doped In2O3 films were deposited under untreated and annealed conditions. The optical parameters of these films were determined based on the transmission–reflection spectra recorded by an ultraviolet–visible spectroscopy laboratory setup. Through four-point probing, energy dispersive spectroscopy, and contact angle measurements, the electronic-band structures and chemical bonding states of the thin films were estimated. The transmission spectra confirmed that the post-annealing treatment promoted film homogeneity. Deeper insights into the optical parameters revealed that annealing encouraged Sn atom incorporation into the film structure and better stable phase formation. The incorporation of Sn atoms resulted in the substitution of Sn4+ into the In3+ sites of the In2O3 lattice and formation of the SnO phase. Notably, our evaluation of the film properties based on data acquired from ultraviolet–visible spectroscopy revealed good consistency with the data acquired from Hall-effect, X-ray diffractometry, and X-ray photoelectron spectroscopy investigations.