College of Engineering (COE)

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https://hdl.handle.net/10919/5539

Note: The Department of Biological Systems Engineering is listed within the College of Agriculture and Life Sciences (CALS).

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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.
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.
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.
12th Annual Graduate Student Research Symposium: School of Biomedical Engineering and Sciences
(Virginia Tech, 2013-05-16)
The SBES Graduate Student Research Symposium was developed to provide students and faculty the opportunity to interact and exchange research ideas with colleagues and industry personnel. This program book features a schedule of events and abstracts from the 12th annual symposium held on May 16, 2013, at The Inn at Virginia Tech.
18.1% single palladium atom catalysts on mesoporous covalent organic framework for gas phase hydrogenation of ethylene
Kuo, Chun-Te; Lu, Yubing; Arab, Pezhman; Weeraratne, K. Shamara; El-Kaderi, Hani; Karim, Ayman M. (2021-07-21)
Noble metal single-atom catalysts maximize metal utilization and offer opportunities to design heterogeneous catalysts at the molecular scale. Mesoporous covalent organic frameworks provide an ideal support to stabilize metal single atoms with specific ligand configuration similar to a homogeneous catalyst In this work, a high loading of single Pd atoms, 18.1 wt %, on mesoporous imine-linked covalent organic framework was synthesized, characterized, and evaluated for ethylene hydrogenation. X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and diffuse-reflectance infrared Fourier transform spectroscopy of adsorbed CO demonstrate that the Pd is atomically dispersed with a highly homogeneous local coordination. The Pd single atoms are active for hydrogenation of ethylene to ethane at room temperature. The study demonstrates that mesoporous COFs provide a large number of identical metal binding sites that are good candidates for immobilizing metal single atoms and their use in gas-phase catalytic applications.
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.
2012 CPES Annual Report
Center for Power Electronics Systems (Virginia Tech. Center for Power Electronics Systems, 2012)
The Center for Power Electronics Systems at Virginia Tech is a research center dedicated to improving electrical power processing and distribution that impact systems of all sizes – from battery – operated electronics to vehicles to regional and national electrical distribution systems. Our mission is to provide leadership through global collaborative research and education for creating advanced electric power processing systems of the highest value to society. CPES, with annual research expenditures about $4-5 million US dollars, has a worldwide reputation for its research advances, its work with industry, and its many talented graduates. From its background as an Engineering Research Center for the National Science Foundation during 1998 - 2008, CPES has continued to work towards making electric power processing more efficient and more exact in order to reduce energy consumption. Power electronics is the “enabling infrastructure technology” that promotes the conversion of electrical power from its raw form to the form needed by machines, motors and electronic equipment. Advances in power electronics can reduce power conversion loss and in turn increase energy efficiency of equipment and processes using electrical power. This results in increased industrial productivity and product quality. With widespread use of power electronics technology, the United States would be able to cut electrical energy consumption by 33 percent. This energy savings in the United States alone is estimated to be the equivalent of output from 840 fossil fuel based generating plants. This savings would result in enormous economic, environmental and social benefits.
2012 Via Report
(Virginia Tech, 2012)
This is the 2012 annual report for the Charles E. Via Jr. Department of Civil and Environmental Engineering.
2012-2018 Strategic Plan for the Virginia Tech College of Engineering
(Virginia Tech, 2012)
Virginia Tech’s College of Engineering is one of the finest in the world. This is evidenced by the great demand for admission to the college’s undergraduate and graduate programs, the great demand to hire the college’s graduates or to admit them to graduate school, and the great demand to participate in the college’s research. The excellent reputation of the College of Engineering arises from a “hands on, minds on” philosophy towards engineering education and practice that dates back many decades, and which gives it distinction among other great engineering colleges. The faculty and staff of the College of Engineering are committed to: • Active-learning by our students in highly regarded engineering programs; • Educational trailblazing and the early adoption of new learning technologies; • High quality research which, in the Land Grant tradition, is timely and focused on problems of great importance to society; and • An Ut Prosim spirit of generous service. Looking ahead six years, the College of Engineering will sustain its excellence and distinctiveness by following a strategic plan that is built upon five themes. Theme 1: Provide a high quality environment for teaching, learning and research. Theme 2: Recruit, educate and graduate a high quality and diverse undergraduate student body. Theme 3: Recruit, educate and graduate a high quality and diverse graduate student body. Theme 4: Address problems of regional, national and global importance. Theme 5: Support a diverse community of faculty, staff and students. Sets of emphases and measures are presented for each theme of this strategic plan.
2013 CPES Annual Report
Center for Power Electronics Systems; Uncork-it, Inc. (Virginia Tech. Center for Power Electronics Systems, 2013)
The CPES industrial consortium is designed to cultivate connectivity among researchers in academia and industry, as well as create synergy within the network of industry members. The CPES industrial consortium offers: The best mechanism to stay abreast of technological developments in power electronics; The ideal forum for networking with leadingedge companies and top-notch researchers; The CPES connection provides the competitive edge to industry members via: Access to state-of-the-art facilities, faculty expertise, top-notch students; Leveraged research funding of over $4-10 million per year; Industry influence via Industry Advisory Board and research champions; Intellectual properties with early access for Principal Plus and Principal members via CPES IPPF (Intellectual Property Protection Fund); Technology transfer made possible via special access to the Center’s multi-disciplinary team of researchers, and resulting publications, presentations and intellectual properties; Continuing education opportunities via professional short courses offered at a significant discount. The CPES industrial consortium offers the ideal forum for networking with leading-edge companies and top-notch researchers and provides the best mechanism to stay abreast of technological developments in power electronics.
2013 Via Report
(Virginia Tech, 2013)
This is the 2013 annual report for the Charles E. Via Jr. Department of Civil and Environmental Engineering.
2014 CPES Annual Report
Center for Power Electronics Systems; Uncork-it, Inc. (Virginia Tech. Center for Power Electronics Systems, 2014)
Over the past two decades, CPES has secured research funding from major industries, such as GE, Rolls-Royce, Boeing, Alstom, ABB, Toyota, Nissan, Raytheon, and MKS, as well as from government agencies including the NSF, DOE, DARPA, ONR, U.S. Army, and the U.S. Air Force, in research pursuing high-density system design. CPES has developed unique high-temperature packaging technology critical to the future powerelectronic industry. In the HDI mini-consortium, the goal of high power density will be pursued following two coupled paths, both leveraging the availability of wide-bandgap power semiconductor, as well as high-temperature passive components and ancillary functions. The switching frequency will be pushed as high as component technologies, thermal management, and reliability permit. At the same time, the maximum component temperatures will be pushed as high as component technologies, thermal management, and reliability permit. The emergence of wide‐bandgap semiconductors such as Silicon Carbide (SiC) and Gallium Nitride (GaN) makes it possible to realize power switches that operate at frequency beyond 5 MHz and temperature beyond 200° C. As the switching frequency increases, switching noise is shifted to higher frequency and can be filtered with small passive components, leading to improved power density. Higher operating temperatures enable increased power density and applications under harsh environments, such as military systems, transportation systems, and outdoor industrial and utility systems.
2014 Via Report
(Virginia Tech, 2014)
This is the 2014 annual report for the Charles E. Via Jr. Department of Civil and Environmental Engineering.
2015 CPES Annual Report
Center for Power Electronics Systems; Uncork-it, Inc. (Virginia Tech. Center for Power Electronics Systems, 2015)
In its efforts to develop power processing systems to take electricity to the next step, CPES has developed research expertise encompassing five technology areas: (1) power conversion technologies and architectures; (2) power electronics components; (3) modeling and control; (4) EMI and power quality; (5) high density integration. These technology areas target applications that include: (1) Power management for information and communications technology; (2) Point-of-load conversion for power supplies; (3) Vehicular power conversion systems; (4) Renewable energy systems. In 2015, CPES sponsored research totaled approximately $2.2 million. The following abstracts provide a quick insight to the current research efforts.
2015 Student Symposium: Department of Biomedical Engineering and Mechanics
(Virginia Tech, 2015)
This program book includes a schedule of events and abstracts from the 14th annual School of Biomedical Engineering & Sciences Graduate Student Research Symposium.
2015 Via Report
(Virginia Tech, 2015)
Department head’s message: Greetings from Blacksburg! Once again it is our pleasure to present the annual edition of the Via Report. I hope you enjoy the excellent articles on several of the outstanding research efforts that are in progress within the department. The work highlighted in these articles supports students in the department and serves society in general, particularly in the Commonwealth, as many of the issues that our faculty are researching are highly important in Virginia. Rest assured that these are but a few of the many great things in progress!
2016 CPES Annual Report
Center for Power Electronics Systems; Uncork-it, Inc. (Virginia Tech. Center for Power Electronics Systems, 2016)
In its effort to develop power processing systems to take electricity to the next step, CPES has cultivated research expertise encompassing five technology areas: (1) power conversion technologies and architectures; (2) power electronics components; (3) modeling and control; (4) EMI and power quality; and (5) high density integration. These technology areas target applications that include: (1) Power management for information and communications technology; (2) Point-of-load conversion for power supplies; (3) Vehicular power converter systems; and (4) High-power conversion systems. In 2016, CPES sponsored research totaled approximately $2.1 million. The following abstracts provide a quick insight to the current research efforts.
2016 Student Symposium: Department of Biomedical Engineering and Mechanics
(Virginia Tech, 2016)
The SBES Graduate Student Research Symposium was developed to provide students and faculty the opportunity to interact and exchange research ideas with colleagues and industry personnel. This program book includes a schedule of events and abstracts from student oral and poster presentations.
2016 Via Report
(Virginia Tech, 2016)
Department head’s message: Greetings from Blacksburg! Once again it is our pleasure to present the annual edition of the Via Report. This year’s report is especially memorable because it is the 30th edition. We will have the opportunity to recognize the current Via scholars, and alumni of the program at our annual Via Banquet in December. I know that the Via family would be proud of the work these students are doing and their service to society in general. I hope you enjoy the excellent articles on several of the outstanding research efforts that are in progress within the department.
2017 CPES Annual Report
Center for Power Electronics Systems; Uncork-it, Inc. (Virginia Tech. Center for Power Electronics Systems, 2017)
In its effort to develop power processing systems to take electricity to the next step, CPES has cultivated research expertise encompassing five technology areas: (1) power conversion technologies and architectures; (2) power electronics components; (3) modeling and control; (4) EMI and power quality; and (5) high density integration. These technology areas target applications that include: (1) power management for information and communications technology; (2) point-of-load conversion for power supplies; (3) vehicular power converter systems; and (4) high-power conversion systems. In 2016, CPES sponsored research totaled approximately $2.4 million. The following abstracts provide a quick insight to the current research efforts.

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