The wide band gap and high breakdown field of β-Ga2O3 single crystals and thin films have recently attracted considerable attention not only for high-power applications, fabricating devices such as transistors and diodes, but also for several other applications such as deep-UV (DUV) sensors, with a cutoff at ∼280 nm, resulting in visible-blind detectors. Currently, most of the UV- and DUV-based simple metal−semiconductor− metal (MSM) systems use interdigitated electrodes, which requires high-quality, defect-free films. β-Ga2O3 films deposited by simple methods such as magnetron sputtering are scarce, and most high-quality β-Ga2O3 thin films have been demonstrated using pulsed laser deposition (PLD) and molecular beam epitaxy (MBE). Herein, we show a comprehensive study to effectively control the structural, optical, and electrical properties of β-Ga2O3 thin films deposited by sputtering. Highly oriented polycrystalline or nanocrystalline n-type β-Ga2O3 thin films were deposited by this method and evaluated as DUV detectors using a simple MSM structure under DUV light with 254 and 232 nm wavelengths. Different structures varying the number of fingers Are evaluated, under different light intensities and applying different electric fields. High responsivities are obtained, especially for nanocrystalline β-Ga2O3 thin films. The high responsivity for both films is attributed to self-trapped holes resulting in an internal gain. Higher responsivity is also observed for higher electric fields, lower light intensities, and a smaller number of fingers. Rise and decay times are comparable, in the range of 11−13 and 14−15 ms, respectively. Our results indicate that sputtered β-Ga2O3 thin films are promising for visible-blind DUV detectors. The paper also demonstrates simple strategies to control the crystallinity of sputtered β-Ga2O3 thin films.
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© 2020 American Chemical Society
- Gallium oxide
- Magnetron sputtering
- Thin films
- UV detector
- Wide band gap