The Effect of Annealing Ambience on the Material and Photodetector Characteristics of Sputtered ZnGa2O4 Films

Abstract

Spinel ZnGa2O4 films were grown on c-plane sapphire substrates at the substrate temperature of 400 °C by radio-frequency magnetron sputtering. Post thermal annealing was employed at the annealing temperature of 700 °C in order to enhance their crystal quality. The effect of thermal annealing on the microstructural and optoelectronic properties of ZnGa2O4 films was systematically investigated in various ambiences, such as air, nitrogen, and oxygen. The X-ray diffraction patterns of annealed ZnGa2O4 films showed the crystalline structure to have (111) crystallographic planes. Transmission electron micrographs verified that ZnGa2O4 film annealed under air ambience possesses a quasi-single-crystalline structure. This ZnGa2O4 film annealed under air ambience exhibited a smooth surface, an excellent average transmittance above 82% in the visible region, and a wide bandgap of 5.05 eV. The oxygen vacancies under different annealing ambiences were revealed a substantial impact on the material and photodetector characteristics by X-ray photoelectron spectrum investigations. ZnGa2O4 film exhibits optimal performance as a metal-semiconductor-metal photodetector when annealed under air ambience. Under these conditions, ZnGa2O4 film exhibits a higher photo/dark current ratio of ~104 order, as well as a high responsivity of 2.53 A/W at the bias of 5 V under an incident optical light of 240 nm. These results demonstrate that quasi-single-crystalline ZnGa2O4 films have significant potential in deep-ultraviolet applications.

Influence of different annealing ambient on terbium oxide passivation layers sputtered using the RF sputtering on silicon substrate

“…However, an increase in the δ value for the Tb 4 O 7 passivation layer annealed in NON ambient to (4.5031 × 10 −4 nm −2 ) was observed. The increase in the Tb 4 O 7 passivation layer annealed in NON ambient may be attributed to the increase in O 2 adsorption and diffusion activity while decreasing oxygen defect/vacancies (V o ) available for N 2 attachment reported elsewhere [56]. Hence, it was hypothesized that the increase in crystallite size occurs due to the decrease in lattice parameters, microstrain, and dislocation density of the investigated materials [57].…”

Growth optimization, optical, and dielectric properties of heteroepitaxially grown ultrawide-bandgap ZnGa2O4 (111) thin film

“…Finally, the XRD spectrum for the ZGO thin film deposited using the Zn-rich (98% ZnO-2% Ga 2 O 3 ) target illustrates single-crystalline XRD peaks at 18.48°, 37.44°, 57.49°, and 79.76°, which corresponds to the cubic phase of the ZGO thin film (JCPDS-381240). 30 In order to view distinctly the difference between the XRD peaks of the β-Ga 2 O 3 and ZGO thin film, an enlarged view of the (111) planes is shown in Fig. 1(b).…”