Enhancing TCO Performance: Low-Temperature PEALD-Deposited In2O3 Thin Films

This study investigates the electrical and optical properties of In2O3 thin films deposited via plasma-enhanced atomic layer deposition (PEALD) at 373 K using DIP-3 and DIP-4 indium precursors. Although a reduction in resistivity with increasing thickness was expected, this study focuses on analyzing the thickness-dependent characteristics of DIP-3, which exhibits superior carrier concentration, and DIP-4, which demonstrates higher mobility. Hall measurements showed that DIP-3 maintained a stable carrier concentration, with mobility increasing up to 80 nm, achieving a minimum resistivity of 6.7 × 10⁻⁴ Ω•cm. However, at 100 nm, mobility degradation due to grain boundary scattering led to increased resistivity. In contrast, DIP-4 exhibited a decrease in carrier concentration with increasing thickness, while X-ray photoelectron spectroscopy (XPS) confirmed that this reduction was primarily governed by grain growth rather than oxygen vacancy variation. Transmittance measurements showed that all films maintained over 85% transmittance in the visible range, with a gradual decrease as thickness increased. DIP-4 exhibited a more pronounced transmittance reduction from 50 nm onward due to increased internal scattering compared to DIP-3. These findings highlight the critical role of precursor selection in modulating microstructural evolution, charge transport behavior, and optical performance, offering guidance for optimizing low-temperature PEALD-based TCOs.