Browsing by Author "Qin, Yuan"

Now showing 1 - 7 of 7
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    1 kV GaN-on-Si Quasi-Vertical Schottky Rectifier
    Qin, Yuan; Xiao, Ming; Zhang, Ruizhe; Xie, Qingyun; Palacios, Tomás; Wang, Boyan; Ma, Yunwei; Kravchenko, Ivan; Briggs, Dayrl P.; Hensley, Dale K.; Srijanto, Bernadeta R.; Zhang, Yuhao (IEEE, 2023-07)
    This work demonstrates quasi-vertical GaN Schottky barrier diodes (SBDs) on 6-inch Si substrate with a breakdown voltage (BV) over 1 kV, the highest BV reported in vertical GaN-on-Si SBDs to date. The deep mesa inherently in quasi-vertical devices is leveraged to form a self-aligned edge termination, and the mesa sidewall is covered by the p-type nickel oxide (NiO) as a reduced surface field (RESURF) structure. This novel termination enables a parallel-plane junction electric field of 2.8 MV/cm. The device also shows low turn-on voltage of 0.5 V, and low specific on-resistance of 1.1 m ·cm2. Moreover, the device exhibits excellent overvoltage robustness under the continuous 800 V stress in the unclamped inductive switching test. These results show the good promise of the low-cost vertical GaN-on-Si power diodes.
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    1 kV Self-Aligned Vertical GaN Superjunction Diode
    Ma, Yunwei; Porter, Matthew; Qin, Yuan; Spencer, Joseph; Du, Zhonghao; Xiao, Ming; Wang, Yifan; Kravchenko, Ivan; Briggs, Dayrl P.; Hensley, Dale K.; Udrea, Florin; Tadjer, Marko; Wang, Han; Zhang, Yuhao (IEEE, 2024-01)
    This work demonstrates vertical GaN superjunction (SJ) diodes fabricated via a novel self-aligned process. The SJ comprises n-GaN pillars wrapped by the charge-balanced p-type nickel oxide (NiO). After the NiO sputtering around GaN pillars, the self-aligned process exposes the top pillar surfaces without the need for additional lithography or a patterned NiO etching which is usually difficult. The GaN SJ diode shows a breakdown voltage (B V) of 1100 V, a specific on-resistance ( RON) of 0.4 mΩ⋅ cm2, and a SJ drift-region resistance ( Rdr) of 0.13 mΩ⋅ cm2. The device also exhibits good thermal stability with B V retained over 1 kV and RON dropped to 0.3 mΩ⋅ cm2 at 125oC . The trade-off between B V and Rdr is superior to the 1D GaN limit. These results show the promise of vertical GaN SJ power devices. The self-aligned process is applicable for fabricating the heterogeneous SJ based on various wide- and ultra-wide bandgap semiconductors.
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    10-kV Ga2O3 Charge-Balance Schottky Rectifier Operational at 200 ◦C
    Qin, Yuan; Xiao, Ming; Porter, Matthew; Ma, Yunwei; Spencer, Joseph; Du, Zhonghao; Jacobs, Alan G.; Sasaki, Kohei; Wang, Han; Tadjer, Marko; Zhang, Yuhao (IEEE, 2023-08)
    This work demonstrates a lateral Ga2O3 Schottky barrier diode (SBD) with a breakdown voltage (BV) over 10 kV, the highest BV reported in Ga2O3 devices to date. The 10 kV SBD shows good thermal stability up to 200◦C, which is among the highest operational temperatures reported in multi-kilovolt Ga2O3 devices. The key device design for achieving such high BV is a reduced surface field (RESURF) structure based on the p-type nickel oxide (NiO), which balances the depletion charges in the n-Ga2O3 channel at high voltage. At BV, the chargebalanced Ga2O3 SBD shows an average lateral electric field (E-field) over 4.7 MV/cm at 25 ◦C and over 3.5 MV/cm at 200◦C, both of which exceed the critical E-field of GaN and SiC. The 10 kV SBD shows a specific on-resistance of 0.27 ·cm2 and a turn-on voltage of 1 V; at 200◦C, the former doubles and the latter reduces to 0.7 V. These results suggest the good potential of Ga2O3 devices for mediumand high-voltage, high-temperature power applications.
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    2 kV, 0.7 mΩ·cm2 Vertical Ga2O3 Superjunction Schottky Rectifier with Dynamic Robustness
    Qin, Yuan; Porter, Matthew; Xiao, Ming; Du, Zhonghao; Zhang, Hongming; Ma, Yunwei; Spencer, Joseph; Wang, Boyan; Song, Qihao; Sasaki, Kohei; Lin, Chia-Hung; Kravchenko, Ivan; Briggs, Dayrl P.; Hensley, Dale K.; Tadjer, Marko; Wang, Han; Zhang, Yuhao (IEEE, 2023)
    We report the first experimental demonstration of a vertical superjunction device in ultra-wide bandgap (UWBG) Ga2O3. The device features 1.8 μm wide, 2×1017 cm-3 doped n-Ga2O3 pillars wrapped by the charge-balanced p-type nickel oxide (NiO). The sidewall NiO is sputtered through a novel self-align process. Benefitted from the high doping in Ga2O3, the superjunction Schottky barrier diode (SJ-SBD) achieves a ultra-low specific on-resistance (RON,SP) of 0.7 mΩ·cm2 with a low turn-on voltage of 1 V and high breakdown voltage (BV) of 2000 V. The RON,SP~BV trade-off is among the best in all WBG and UWBG power SBDs. The device also shows good thermal stability with BV > 1.8 kV at 175 oC. In the unclamped inductive switching tests, the device shows a dynamic BV of 2.2 kV and no degradation under 1.7 kV repetitive switching, verifying the fast acceptor depletion in NiO under dynamic switching. Such high-temperature and switching robustness are reported for the first time in a heterogeneous superjunction. These results show the great potential of UWBG superjunction power devices.
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    Artificial Neuronal Devices Based on Emerging Materials: Neuronal Dynamics and Applications
    Liu, Hefei; Qin, Yuan; Chen, Hung-Yu; Wu, Jiangbin; Ma, Jiahui; Du, Zhonghao; Wang, Nan; Zou, Jingyi; Lin, Sen; Zhang, Xu; Zhang, Yuhao; Wang, Han (Wiley-V C H Verlag, 2023-03)
    Artificial neuronal devices are critical building blocks of neuromorphic computing systems and currently the subject of intense research motivated by application needs from new computing technology and more realistic brain emulation. Researchers have proposed a range of device concepts that can mimic neuronal dynamics and functions. Although the switching physics and device structures of these artificial neurons are largely different, their behaviors can be described by several neuron models in a more unified manner. In this paper, the reports of artificial neuronal devices based on emerging volatile switching materials are reviewed from the perspective of the demonstrated neuron models, with a focus on the neuronal functions implemented in these devices and the exploitation of these functions for computational and sensing applications. Furthermore, the neuroscience inspirations and engineering methods to enrich the neuronal dynamics that remain to be implemented in artificial neuronal devices and networks toward realizing the full functionalities of biological neurons are discussed.
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    Recent progress of Ga2O3 power technology: large-area devices, packaging and applications
    Qin, Yuan; Wang, Zhengpeng; Sasaki, Kohei; Ye, Jiandong; Zhang, Yuhao (IOP Publishing, 2023-06)
    Benefitted from progress on the large-diameter Ga2O3 wafers and Ga2O3 processing techniques, the Ga2O3 power device technology has witnessed fast advances toward power electronics applications. Recently, reports on large-area (ampere-class) Ga2O3 power devices have emerged globally, and the scope of these works have gone well beyond the bare-die device demonstration into the device packaging, circuit testing, and ruggedness evaluation. These results have placed Ga2O3 in a unique position as the only ultra-wide bandgap semiconductor reaching these indispensable milestones for power device development. This paper presents a timely review on the state-of-the-art of the ampere-class Ga2O3 power devices (current up to >100 A and voltage up to >2000 V), including their static electrical performance, switching characteristics, packaging and thermal management, and the overcurrent/overvoltage ruggedness and reliability. Exciting research opportunities and critical technological gaps are also discussed.
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    Thermal management and packaging of wide and ultra-wide bandgap power devices: a review and perspective
    Qin, Yuan; Albano, Benjamin; Spencer, Joseph; Lundh, James Spencer; Wang, Boyan; Buttay, Cyril; Tadjer, Marko; DiMarino, Christina; Zhang, Yuhao (IOP Publishing, 2023-03)
    Power semiconductor devices are fundamental drivers for advances in power electronics, the technology for electric energy conversion. Power devices based on wide-bandgap (WBG) and ultra-wide bandgap (UWBG) semiconductors allow for a smaller chip size, lower loss and higher frequency compared with their silicon (Si) counterparts, thus enabling a higher system efficiency and smaller form factor. Amongst the challenges for the development and deployment of WBG and UWBG devices is the efficient dissipation of heat, an unavoidable by-product of the higher power density. To mitigate the performance limitations and reliability issues caused by self-heating, thermal management is required at both device and package levels. Packaging in particular is a crucial milestone for the development of any power device technology; WBG and UWBG devices have both reached this milestone recently. This paper provides a timely review of the thermal management of WBG and UWBG power devices with an emphasis on packaged devices. Additionally, emerging UWBG devices hold good promise for high-temperature applications due to their low intrinsic carrier density and increased dopant ionization at elevated temperatures. The fulfillment of this promise in system applications, in conjunction with overcoming the thermal limitations of some UWBG materials, requires new thermal management and packaging technologies. To this end, we provide perspectives on the relevant challenges, potential solutions and research opportunities, highlighting the pressing needs for device-package electrothermal co-design and high-temperature packages that can withstand the high electric fields expected in UWBG devices.