Effects of heat treatment on the electrical and optical properties of amorphous oxide semiconductor films deposited by pulsed laser deposition for a high-performance transparent conducting electrode

Abstract

We report the effect of substrate temperature (room temperature (RT), 100 °C, 200 °C, 300 °C, and 400 °C) on the optical and electrical properties of amorphous oxide semiconductors (AOSs), SiInZnO (SIZO), SiZnSnO (SZTO), and InGaZnO (IGZO) thin films deposited using pulsed laser deposition (PLD). The optical properties of AOSs were observed through UV–Vis–NIR spectroscopy and photoluminescence spectroscopy. The violet emission, yellow-green emission, yellow emission, and orange-red emission band were observed in the photoluminescence study. All the films show very high transparency. The transmittance value for all the film drops approximately from 94 to 67% as the substrate temperature rises from RT to 400 °C due to increased absorption. The Hall measurement results indicated that substrate temperature greatly impacts the carrier concentration (n), carrier mobility (µ), and resistivity (ρ), of AOSs films. With rising substrate temperature, the carrier concentration increases, suggesting that certain dopant atoms at the grain boundaries may undergo thermal ionization, which can subsequently diffuse into the host lattice, thereby acting as effective dopants. The enhancement of mobility is likely due to increase in grain size. The decrease in resistivity is due to increased carrier concentration and mobility. We hope that the developed AOSs thin films having high transparency (over 94%), with a carrier concentration in the range of 2 × 10^–18 cm⁻³ to 8.19595 × 10^–19 cm⁻³, mobility in the range of 0.38–3.5 cm²/Vs and resistivity from 6 to 2.62 × 10^–2 Ωcm can possibly be used for developing high-performance transparent conducting electrodes.