Ultrasensitive UV-C detection based on MOCVD-grown highly crystalline ultrawide bandgap orthorhombic κ-Ga2O3

• Published in: Applied surface science 2023-01, Vol.609, p.155350, Article 155350
• Main Authors: Lim, Namsoo, Min, Jungwook, Min, Jung-Hong, Hong Kang, Chun, Li, Kuang-Hui, Park, Tae-Yong, Kim, Woochul, Davaasuren, Bambar, Khee Ng, Tien, Ooi, Boon S., Ha Woo, Deok, Park, Ji-Hyeon, Pak, Yusin
• Format: Article
• Language: English
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.155350

[Display omitted] •The Si-doped κ-Ga2O3 thin film was grown on a 2-inch sapphire wafer by MOCVD and applied to a solar-blind photodetector.•Highly crystalline κ-Ga2O3 thin film with the bandgap of ∼4.9 eV was confirmed by Tauc plot, XRD, and TEM analyses.•The κ-Ga2O3 thin film grown under 15 sccm SiH4 showed excellent UV-C detecting performances (∼72.1 A/W, Ion/Ioff ∼14). Orthorhombic κ-Ga2O3, as one of the Ga2O3 polymorphs, is considered a promising as ultrawide bandgap material for extreme environment devices. It is considered more superior than the conventional group III-V compound semiconductors and silicon carbides in extreme environments demanding material/device characteristics of high-voltage, high-temperature, high-pressure, high-impact, and high-radiation. In this study, we demonstrate ultrasensitive ultraviolet-C (UV-C) detection using Si-doped orthorhombic κ-Ga2O3 photodetectors. A 150 nm thick κ-Ga2O3 film was grown on a 2-inch diameter sapphire (α–Al2O3) wafer via metal organic chemical vapor deposition (MOCVD) method. The crystallinity of orthorhombic κ-Ga2O3 film was investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The ultrawide bandgap of approximately 4.9 eV was confirmed by UV transmittance measurement. For UV-C detection analysis, a planar device with a channel length of 20 μm was fabricated using Au/Ti metal contacts on the orthorhombic κ-Ga2O3 film. The device doped under 15 sccm SiH4 flow rate showed ultrahigh photoresponse of ∼72.1 A/W, Ion/Ioff of ∼14, and decent rise (∼0.35 s) and decay (∼1.79 s). Our results will contribute to the understanding on a new material phase of κ-Ga2O3, as well as on developing optoelectronics devices with high radiation hardness suitable for operation in extreme environments.