【Epitaxy Papers】RF sputtered Ga₂O₃ thin-films for solar-blind UV-C detection: Investigating effects of crystallinity, stoichiometry, and ambient

      Researchers from the RMIT University have published a dissertation titled "RF sputtered Ga₂O₃ thin-films for solar-blind UV-C detection: Investigating effects of crystallinity, stoichiometry, and ambient" in APL Electronic Devices.

Abstract

      The ultraviolet photo-responses of metal–semiconductor–metal (MSM) devices formed on RF sputtered thin film gallium oxide have been investigated as a function of the stoichiometry and crystallinity of the films and the ambient conditions during illumination. Stoichiometry was altered via the oxygen pressure during growth, and crystallinity was altered via the growth surface; amorphous Ga₂O₃ films were grown on Si₃N₄, while polycrystalline β-Ga₂O₃ films were grown on a-plane sapphire. Interdigitated Pt–Ga₂O₃–Pt MSM photodetectors were fabricated on the Ga₂O₃ films, and selective UV-C detection was consistently observed. Under an incident optical power of 0.09 mW/cm², on/off current ratios (I_UV-C:I_dark) in the best devices exceeded 10³:1. Other figures of merit included responsivity as high as 2.0 A/W and detectivity up to 1.2 × 10¹³ Jones. Operation in air of 90% relative humidity produced the fastest UV-C response times but the highest dark current, attributed to interaction between water and oxygen surface adsorbates, which affected surface band-bending. Comparison with encapsulated devices enabled identification of trap and surface adsorbate limited components of the device response and recovery. Finally, a self-powered (zero bias) interdigitated Pt–Ga₂O₃–C UV-C photodetector was tested, and this device exhibited a responsivity of 1.1 × 10⁻² A/W and a detectivity of 3.7 × 10¹⁰ Jones under 0.09 mW/cm² UV-C illumination.

DOI：

https://doi.org/10.1063/5.0293906