Studying the structural, optical, and electrical characteristics of Zn2SnO4 films using a direct current magnetron sputtering method

Abstract

In this study, the characteristics of ZTO films are examined by varying the substrate temperature at an Ar ambient pressure of 3 × 10−3 Torr. The elemental content of Zn, Sn, and O in the generated Zn2SnO4 films was confirmed using X-ray dispersive and X-ray photoelectron spectroscopy. The result reveals that the Zn/Sn ratio for the film formed at 300 °C reaches 2. The (222) and (311) lattice planes validated the cubic inverse spinel structure of ZTO films in the X-ray diffraction investigation. Atomic force microscopy was used to measure surface roughness, and the RMS rose in a range of 1.34–4.79 nm as the substrate temperature increased. Field-emission scanning electron microscopy revealed that the average crystal grain size grew in the region of 60–95 nm as the substrate temperature increased. The UV–vis absorption edge shift validates the Burstein-Moss shift rule, with a bandgap of ZTO-300 achieving the greatest value of 3.75 eV, corresponding to the largest carrier concentration. Electrical characteristics were investigated using Hall measurements. Film conductivity was primarily determined by the electron concentration or the presence of oxygen vacancies. The lowest resistivity measured was 5.4 × 10−3 Ω cm, which corresponded to an electron concentration of 8.57 × 1019 cm−3. The current-voltage characteristics of the ZTO/p-Si junction proved its rectifiable quality. Because of the low resistivity of the ZTO-300 sample, the ZTO-300/p-Si heterojunction has the largest photocurrent (4.72 10−3 A), making it suitable for use in optoelectronic devices.