Optical and electrical properties of ITO/Metal/NiO triple-layer grown by PVD method: An experimental study

Abstract

In this work, transparent conducting oxides (TCOs) comprising an ITO/Metal/NiO sandwich structure grown by sputtering and thermal evaporation in a vacuum are investigated. By exploiting the four-point probe measurements and optical spectrometry both optical and electrical characteristics of the fabricated ITO/Metal/NiO trilayers for diverse metals such as Au, Ag, and Cu are studied. Moreover, through X-ray diffraction and high-resolution scanning electron microscopy method the structural characteristics are fully examined. The results reveal that the type of innermost metal plays the main role in the optical and electrical behavior of the trilayers structure. An average transmittance of 73-62% range at visible wavelength and small resistivity of 2 × 10−4 Ω cm are achieved for a 10 nm thick Au interlayer. The sheet resistivity (Rs) of NiO drops drastically from 200 Ω (single NiO layer) to 1.2Ω for ITO/Cu/NiO structure. Moreover, an increase in sputtering power and film thickness increases the optical bandgap. The obtained results prove that physical vapor deposition (PVD) is a good method for producing par excellence TCO films with beneficial characteristics such as high transmittance and low resistivity.