Dependence of Ga-doped ZnO thin film properties on different sputtering process parameters: Substrate temperature, sputtering pressure and bias voltage

Abstract

This paper reports on the effects of different sputtering deposition process parameters (substrate temperature, sputtering pressure and bias voltage) on the electrical, optical, structural and morphological properties of gallium-doped ZnO (ZnO:Ga) of~1 μm thick. These highly transparent and conductive films were deposited on glass surfaces by d.c. pulsed magnetron sputtering from a GZO (ZnO(95.5):Ga 2 O 3 (4.5)) ceramic target in an argon atmosphere. X-ray diffraction experiments show that all films have a hexagonal wurtzite structure with the [001] preferred crystallographic direction, and the morphology of the films (obtained from scanning electron microscope analysis) is sensitive to the process parameters. All ZnO:Ga films have an average transmittance above 80% in the visible region, and the lowest electrical resistivity of 3.03 × 10 −4 Ω•cm was achieved for the sample submitted to the lowest bias voltage (−40 V), which corresponds to a carrier concentration and a carrier mobility of 6.99 × 10 20 cm −3 and 29.49 cm 2 V −1 s −1 , respectively. A high substrate temperature, high sputtering pressure and low negative bias voltage (within the range of studied parameters) proved to be very promising on obtaining optimized ZnO:Ga films, ensuring suitable properties for application as transparent electrodes in photovoltaic cells.

Magnetron Sputtering for ZnO:Ga Scintillation Film Production and Its Application Research Status in Nuclear Detection

“…When the sputtering pressure increases from 0.5 Pa to 1.0 Pa, all electric properties of the films are improved [75,100]. As the pressure continues to rise, the sputtered particles continue to be oxidized, and oxygen in the grain boundary gap is excessive, which leads to the formation of Ga 2 O 3 and the deterioration of electrical properties [103,105]. The average transmittance is independent of the sputtering pressure, and it can reach 90% or even higher in the visible region, as shown in Figure 8 [75].…”

Investigation of the Properties of Al-doped ZnO Thin Films with Sputtering Pressure Deposition by RF Magnetron Sputtering

“…On the one hand, at very low sputtering pressures (lower than 0.80 Pa) the particles when arriving at the substrate surface do not have enough energy (and therefore have low mobility), resulting in more irregular crystalline lattice formation [4]. On the other hand, the increase in the sputtering pressure above 0.80 Pa and concomitant reduction in the energy of the sputtered particles leads to a decrease in the intensity of diffraction peak [4]. Fig.…”

Transparent Amorphous Oxide Semiconductor as Excellent Thermoelectric Materials

“…From a material point of view, oxide semiconductors have attracted much attention due to their lower toxicities and lower prices compared to Te compounds, which are widely used and studied TE materials [2,3]. In 2 O 3 based and ZnO based oxides have been extensively investigated as the transparent conductive oxide for their high electrical conductivity (~3 × 10 −4 Ω•cm), high transmittance (over 80%), and remarkable thermal stability at high temperature [17,18].…”