Browsing by Author "He, Ziyi"

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    Characterizations of two-photon absorption process induced by defects in aluminum nitride using Z-scan method
    (IOP Publishing, 2024) Zhou, Jingan; Li, Tao; Zhao, Xuan; Zhang, Xiang; Doumani, Jacques; Xu, Mingfei; He, Ziyi; Luo, Shisong; Mei, Zhaobo; Chang, Cheng; Robinson, Jacob T.; Ajayan, Pulickel M.; Kono, Junichiro; Zhao, Yuji; Smalley-Curl Institute
    In this work, we reported two-photon absorption (TPA) measurements for aluminum vacancies in Aluminum nitride single crystals. We measured the linear transmission and identified the defect levels. Using the Z-scan method, we measured the TPA coefficients of the transitions between defect levels from 380 nm to 735 nm. The transition occurs between the aluminum vacancies defect levels. Furthermore, the power dependence shows good linear fitting, confirming the TPA mechanism. These results will be helpful for the design and fabrication of ultra-low loss waveguides and integrated photonics in the ultraviolet spectral range.
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    β-Ga2O3-Based Heterostructures and Heterojunctions for Power Electronics: A Review of the Recent Advances
    (MDPI, 2024) Herath Mudiyanselage, Dinusha; Da, Bingcheng; Adivarahan, Jayashree; Wang, Dawei; He, Ziyi; Fu, Kai; Zhao, Yuji; Fu, Houqiang
    During the past decade, Gallium Oxide (Ga2O3) has attracted intensive research interest as an ultra-wide-bandgap (UWBG) semiconductor due to its unique characteristics, such as a large bandgap of 4.5–4.9 eV, a high critical electric field of ~8 MV/cm, and a high Baliga’s figure of merit (BFOM). Unipolar β-Ga2O3 devices such as Schottky barrier diodes (SBDs) and field-effect transistors (FETs) have been demonstrated. Recently, there has been growing attention toward developing β-Ga2O3-based heterostructures and heterojunctions, which is mainly driven by the lack of p-type doping and the exploration of multidimensional device architectures to enhance power electronics’ performance. This paper will review the most recent advances in β-Ga2O3 heterostructures and heterojunctions for power electronics, including NiOx/β-Ga2O3, β-(AlxGa1−x)2O3/β-Ga2O3, and β-Ga2O3 heterojunctions/heterostructures with other wide- and ultra-wide-bandgap materials and the integration of two-dimensional (2D) materials with β-Ga2O3. Discussions of the deposition, fabrication, and operating principles of these heterostructures and heterojunctions and the associated device performance will be provided. This comprehensive review will serve as a critical reference for researchers engaged in materials science, wide- and ultra-wide-bandgap semiconductors, and power electronics and benefits the future study and development of β-Ga2O3-based heterostructures and heterojunctions and associated power electronics.