Characteristics of GaTiZnO coatings deposited by magnetron sputtering

Gallium-titanium-zinc oxide (GaTiZnO) thin transparent conducting films (TCFs) were fabricated through the radio-frequency (RF) magnetron sputtering technique. A comprehensive analysis was conducted to assess the impact of deposition power on their structural, morphological, optoelectronic, and nonlinear optical properties. Ultraviolet (UV)-visible spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and Hall effect measurements were employed for this analysis. The XRD analysis reveals that all TCFs exhibit a wurtzite hexagonal crystal structure, predominantly oriented along the (002) plane. Deposition power significantly influences the properties of GaTiZnO TCFs. Initially, microstrain, resistivity and dislocation density reduce with increasing power, but then they begin to increase. However, the mean grain size, visible transmittance, and merit figure show reverse trends. The GaTiZnO sample deposited at 200 W exhibits optimal performance, with the highest optoelectronic properties and crystalline quality. It exhibits the highest merit figure and mean visible transmittance, lowest resistivity, largest grain size, least microstrain, and smallest dislocation density, recorded as 1.241 × 10 ⁴ Ω ⁻¹ · cm ⁻¹ , 87.02%, 5.863 × 10 ⁴ Ω· cm, 84.65 nm, 6.162 × 10 ⁻¹ and 1.396 × 10 ⁻⁴ nm ⁻² , respectively. Additionally, the direct optical energygap was estimated using the Tauc plot method, revealing values between 3.342 and 3.501 eV . The Urbach energy, evaluated by the Urbach relation, ranges from 0.173 to 0.191 eV . Optical constants of GaTiZnO TCFs were derived via optical characterization, assessing refractive index dispersion using the Wemple-DiDomenico (WDD) model to determine oscillator parameters and nonlinear optical constants. Notably, all films show normal dispersion in the visible range, with nonlinear optical constants decreasing monotonically as wavelength increases, regardless of deposition power. The optical parameters strongly depend on deposition power.