【Epitaxy Papers】Cycle-ratio-controlled nominal ALD-defined In₂O₃/Ga₂O₃ multilayer films for tunable MSM ultraviolet photodetectors

      Researchers from Xi'an University of Technology have published a dissertation titled " Cycle-ratio-controlled nominal ALD-defined In₂O₃/Ga₂O₃ multilayer films for tunable MSM ultraviolet photodetectors " in Materials Science in Semiconductor Processing.

Abstract

      Gallium oxide (Ga₂O₃), with an ultrawide bandgap of ∼4.9 eV, is a promising semiconductor for ultraviolet photodetection, particularly in the solar-blind UV region. Indium incorporation enables bandgap engineering of Ga₂O₃ and provides an effective route for tuning the UV spectral response. Here, nominal ALD-defined In₂O₃/Ga₂O₃ multilayer films were fabricated via an ALD super-cycle process, and metal–semiconductor–metal (MSM) UV photodetectors with tunable spectral response were subsequently prepared. The influence of the nominal In₂O₃:Ga₂O₃ ALD cycle ratio on the bandgap, surface morphology, and device performance was investigated using three representative cycle ratios. Increasing the In₂O₃:Ga₂O₃ cycle ratio narrowed the optical bandgap and shifted the spectral response toward longer wavelengths. Under 254 nm illumination at a 10 V bias, the IGO-3/15 device exhibited a photo-to-dark current ratio of 103.6, a responsivity of 23.9 A W⁻¹, and rise/fall times of 1.25/0.36 s. Although the IGO-9/9 device exhibited a higher peak responsivity at longer UV wavelengths, its response peak shifted to 310 nm and its transient response became significantly slower. These results indicate that modulation of the In₂O₃:Ga₂O₃ cycle ratio is an effective strategy for tuning the spectral response and optimizing the overall performance of MSM UV photodetectors based on nominal ALD-defined In₂O₃/Ga₂O₃ multilayer films.

DOI：

https://doi.org/10.1016/j.mssp.2026.111007