Optimization of Oxygen Flow for Tailoring the Properties of AZO Thin Films Deposited by DC Magnetron Sputtering

Abstract

This study reports on the preparation of aluminum-doped zinc oxide (AZO) thin films by DC magnetron sputtering using a Zn/Al target. The influence of reactive oxygen gas flow rate (10–100 sccm) was investigated while maintaining a constant Ar flow rate of 40 sccm. Films were deposited on both silicon and glass substrates, and further examined in their as-deposited state as well as after annealing at 400 °C in vacuum for 2 h. Morphological, structural, optical, and electrical properties were systematically characterized by FE-SEM, GI-XRD, UV–Vis–NIR spectroscopy, and Hall effect measurements, respectively. The results reveal that increasing O₂ flow rate affects the deposition rate while the films consistently exhibit a hexagonal wurtzite structure with preferred orientations along (002) and (103). The degree of crystallinity strongly depends on the O₂ concentration. The optical transmittance was found to be in the range of 76.10–84.79%, with estimated band gap energies between 3.32 and 3.52 eV. Notably, AZO thin films deposited at an O₂ flow rate of 20 sccm exhibited optimum electrical properties, including a resistivity of 4.0 × 10⁻³ Ω·cm, conductivity of 246 S/cm, carrier mobility of 5.83 cm²·V⁻¹·s⁻¹, and carrier concentration of 2.66 × 10²⁰ cm⁻³. These findings highlight the critical role of O₂ flow control in tailoring the physical properties of AZO thin films, underscoring their potential for various optoelectronic applications.