Investigation of Gallium Oxide Thin Films Deposited by Sputtering for Photomemristor Applications

Gallium oxide (Ga 2 O 3 ) is an emerging wide bandgap semiconductor material that has garnered significant attention in the field of high‐voltage and high‐frequency power electronics. Five main crystalline phases of Ga 2 O 3 have been identified, including the corundum (α), monoclinic (β), defect spinel (γ), cubic (δ), and orthorhombic (ε) phases. Their thermodynamic stability follows the order of γ, δ, α, ε, and β. Notably, the monoclinic β‐Ga 2 O 3 phase is the most stable, particularly at high temperatures, while the other phases are metastable above room temperature and tend to transform into the β phase under specific thermal conditions. In this study, thin films were deposited using the radiofrequency sputtering technique at three different deposition times: 15, 30, and 60 min. The films were deposited onto p‐type silicon substrates with 300 W power processes. Six devices were fabricated from gallium oxide in the as‐deposited and annealed states. For analysis, Rutherford backscattering spectrometry techniques, scanning electron microscopy, and X‐ray diffraction were employed, confirming the β phase. Through UV–Vis spectroscopy, the reflectance of the material was obtained, enabling the calculation of the bandgap (∼4.36 eV). After depositing metallic contacts, the I – V curve was obtained to study the material nonlinear behavior. From the I – V results of the photomemristors, resistive switching and the photoelectric effect were observed. Gallium oxide is a wide bandgap material; however, it is sensitive to light due to defects in its structure. Such defects enable charge trapping and detrapping, which facilitate resistive switching. Impedance measurements were also performed.