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Steven Ringel

  • Assoc VP & IMR Executive Dir, OR - Inst for Material Res
  • Professor, Neal A Smith Chair, Electrical & Computer Engr.
  • Professor, Materials Science Engineering
  • Professor, Physics
  • 2024 Neil Ave RM 375
    Columbus, OH 43210
  • 614-292-6904



Steven A. Ringel is a Distinguished University Professor and the Associate Vice President for Research at The Ohio State University.  Ringel is also the Neal A. Smith Endowed Chair in Electrical and Computer Engineering at Ohio State, and he is the Executive (Founding) Director of the Institute for Materials Research (IMR). In FY19 IMR executed more than $86M in sponsored research across a base of 26 academic departments and many research centers within IMR’s multi-college umbrella, including OSU’s Nanotech West Lab and Center for Electron Microscopy and Analysis (CEMAS). IMR Signature areas are: (a) Electronic & Photonic Materials & Devices, (b) Materials Characterization, (c) Emergent Materials, (d) Manufacturing & Processing, (e) Magnetic Materials & Phenomena, and (f) Materials for Energy & Sustainability. See for more details. 

Outside of academic leadership, Ringel’s research career has spanned electronic materials and devices based on compound semiconductors with applications in photovoltaics, integrated electronic-optoelectronics, RF and power devices, and energy harvesting; epitaxial growth strategies for compound semiconductor-Si integration; wide bandgap semiconductors; defect characterization methods, defect science and engineering; and translational research and global innovation. Ringel is widely recognized as a global pioneer in photovoltaics, III-V/Si integration and wide bandgap semiconductor characterization. He is the author/co-author of more than 450 journal articles and conference presentations and has given more than 175 invited talks.  Among his honors, Ringel is a Fellow of IEEE, Fellow of AAAS, Associate Fellow of AIAA, former NSF National Young Investigator, and with his students have received 9 best paper/presentation awards. He has held visiting positions in Singapore, Spain and Ireland. In addition to being an Ohio State Distinguished University Professor, Ohio State’s highest faculty title, he has been honored with the Ohio State Distinguished Scholar Award - the university’s highest recognition for scholarly achievement, and the following OSU College of Engineering recognitions: Scott Award, Harrison Award, 4 Lumley research awards, and the College Faculty Mentoring Award.  Ringel is deeply committed to global innovation that connect academic to industry.  Some examples are his founding of the IIT-Bombay/Ohio State Frontier Science and Engineering Research Center, and his role as the current Chair of the Scientific Advisory Board of the Singapore-MIT Alliance for Research and Technology (SMART) for the Low Energy Electronic Systems (LEES) IRG.   Ringel is a co-founder/founder/leadership team of several high tech startups – 4Power LLC, 4GEN LLC, Amberwave and New Silicon Pte LTD.

View Ringel's full CV here.


Ph.D. 1991, Georgia Institute of Technology

Research Interests

Electronic materials and devices, photovoltaics, defect engineering, epitaxy and innovation in defect characterization methods; Broad interests in the science and application of electronic materials for applications in energy, electronics and optoelectronic technologies; Defect engineering in semiconductors and development of methods for trap spectroscopy; with applications to wide bandgap semiconductor devices and new materials; Substrate engineering; heterogeneous integration and interface science; The academic-industry research interface; Translational materials and its role in global innovation in solar energy, next generation electronics and general technology development.


375 Caldwell Laboratory

Personal website


  • June, 2015

    Advisor, Best Student Paper Award: Zeng Zhang.

  • February, 2015

    Distinguished Scholar Award.

  • March, 2014

    Honorary Professor.

  • January, 2014

    Chair, Scientific Advisory Board/Visiting Committee.

  • January, 2014

    Member, Advisory Board.

  • April, 2013

    Invited Tutorial Speaker.

  • January, 2012

    Clara M. and Peter L. Scott Award for Outstanding Achievement.

  • February, 2010

    Lumley Research Award.

  • January, 2004-
    January, 2009

    Invited Guest Lecturer.

  • January, 2008

    Co-investigator of Clean Energy Research Program.

  • January, 2008

    Associate Fellow.

  • January, 2008

    Visiting Professor.

  • July, 2007

    Invited Tutorial Speaker. University of Saint Francis.

  • February, 2005

    Lumley Research Award.

  • January, 2005

    AAAS Fellow.

  • January, 2004

    Advisor, MRS Gold Medal Student Award: A. Armstrong.

  • January, 2004

    Neal A. Smith Endowed Chair.

  • June, 2003

    Advisor, Best Student Paper Award: O. Kwon.

  • June, 2001

    Advisor, Best Student Paper Award: R. Kaplar.

  • November, 2000

    Advisor, MRS Gold Medal Student Award: A. Hierro.

  • February, 2000

    Lumley Research Award.

  • February, 1999

    Stanley F. Harrison Faculty Award for Excellence in Engineering Research & Education.

  • January, 1999

    Stanley E. Harrison Faculty Award for Excellence in Engineering.

  • January, 1994

    National Young Investigator Award.

Edited Books


  • Schwarz, R.B., Ceder, G., Ringel, S.A.. 2002. "Materials for Energy Storage, Generation and Transport." Materials Research Society Press.


  • S.A. Ringel, S.A., Fitzgerald, E.A., Adesida, I., Houghton, D.. 1999. "III-V and IV-IV Materials and Processing Challenges for Highly Integrated Microelectronics and Optoelectronics." Materials Research Society Press.


  • Buckley, D.N., Ringel, S.A., Ren, F.. 1995. "Symposium on Large Area Wafer Growth and Processing for Electronic and Photonic Devices and the Twentieth State of the Art Program on Compound Semiconductors." The Electrochemical Society Press.



  • 2010. "The III-V solar cell on Silicon." In III-V Compound Semiconductors: Integration with Silicon-Based Microelectronics, edited by Li, T., E. Piner, E., Dadgar, A.,


  • 1998. "Electronic Properties and Deep Levels in Germanium-Silicon." In Semiconductors and Semimetals, edited by Bean, J., Hull, R.,


  • 1997. "Hydrogenation of Compound Semiconductors." In Processing Technology for Semiconductors, edited by Pearton, SJ,

Journal Articles


  • Xuan Sang Nguyen,X,S; Goh,Xuan,Long; Zhang,Li; Zhang,Zeng; Arehart,Aaron,R; Ringel,Steven,A; Fitzgerald,Eugene,A; Chua,Soo,Jin, 2016, "Deep level traps in GaN LEDs grown by metal organic vapour phase epitaxy on an 8 inch Si(111) substrate." JAPANESE JOURNAL OF APPLIED PHYSICS 55, no. 6, 060306 - 060306.


  • Sasikumar,A; Arehart,A,R; Via,G,D; Winningham,B; Poling,B; Heller,E; Ringel,S,A, 2015, "Identification of an RF degradation mechanism in GaN based HEMTs triggered by midgap traps." MICROELECTRONICS RELIABILITY 55, no. 11, 2258-2262 - 2258-2262.


  • Chmielewski,Daniel,J; Grassman,Tyler,J; Carlin,Andrew,M; Carlin,John,A; Speelman,Austin,J; Ringel,Steven,A, 2014, "Metamorphic GaAsP Tunnel Junctions for High-Efficiency III-V/IV Multijunction Solar Cell Technology." IEEE JOURNAL OF PHOTOVOLTAICS 4, no. 5, 1301-1305 - 1301-1305.


  • Long,R,D; Jackson,C,M; Yang,J; Hazeghi,A; Hitzman,C; Majety,S; Arehart,A,R; Nishi,Y; Ma,T,P; Ringel,S,A; McIntyre,P,C, 2013, "Interface trap evaluation of Pd/Al2O3/GaN metal oxide semiconductor capacitors and the influence of near-interface hydrogen." APPLIED PHYSICS LETTERS 103, no. 20, 201607 - 201607.


  • Zhang,Z; Hurni,C,A; Arehart,A,R; Yang,J; Myers,R,C; Speck,J,S; Ringel,S,A, 2012, "Deep traps in nonpolar m-plane GaN grown by ammonia-based molecular beam epitaxy." APPLIED PHYSICS LETTERS 100, no. 5, 052114 - 052114.


  • Grassman,Tyler,J; Brenner,Mark,R; Gonzalez,Maria; Carlin,Andrew,M; Unocic,Raymond,R; Dehoff,Ryan,R; Mills,Michael,J; Ringel,Steven,A, 2010, "Characterization of Metamorphic GaAsP/Si Materials and Devices for Photovoltaic Applications." IEEE TRANSACTIONS ON ELECTRON DEVICES 57, no. 12, 3361-3369 - 3361-3369.


  • Yang,Chieh-Kai; Roblin,Patrick; Malonis,Andrew; Arehart,Aaron; Ringel,Steven; Poblenz,Christiane; Pei,Yi; Speck,James; Mishra,Umesh, 2009, "Characterization of Traps in AlGaN/GaN HEMTs with a Combined Large Signal Network Analyzer/Deep Level Optical Spectrometer System." 2009 IEEE/MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM, VOLS 1-3 1-3, 1209-1212 - 1209-1212.
  • Grassman,T,J; Brenner,M,R; Rajagopalan,S; Unocic,R; DEHOFF,R; Mills,M; Fraser,H; Ringel,S,A, 2009, "Control and elimination of nucleation-related defects in GaP/Si(001) heteroepitaxy." APPLIED PHYSICS LETTERS 94, no. 23, 232106 - 232106.


  • Smith,P,E; LUECK,M; Ringel,S,A; BRILLSON,L,J, 2008, "Atomic diffusion and interface electronic structure at In0.49Ga0.51P/GaAs heterojunctions." JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B 26, no. 1, 89-95 - 89-95.
  • Arehart,A,R; Corrion,A; Poblenz,C; Speck,J,S; Mishra,U,K; DenBaars,S,P; Ringel,S,A, 2008, "Comparison of deep level incorporation in ammonia and rf-plasma assisted molecular beam epitaxy n-GaN films." PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 5, NO 6 5, no. 6, 1750-1752 - 1750-1752.


  • Mosbacker,H,L; El Hage,S; Gonzalez,M; Ringel,S,A; Hetzer,M; Look,D,C; Cantwell,G; Zhang,J; Song,J,J; BRILLSON,L,J, 2007, "Role of subsurface defects in metal-ZnO(0001) Schottky barrier formation." JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B 25, no. 4, 1405-1411 - 1405-1411.
  • Smith,P,E; LUECK,M; Ringel,S,A; BRILLSON,L,J, 2007, "Atomic diffusion and electronic structure in Al0.52In0.48P/GaAs heterostructures." JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B 25, no. 6, 1916-1921 - 1916-1921.


  • Armstrong,A; Green,D; Arehart,A,R; Mishra,U,K; Speck,J,S; Ringel,S,A, 2005, "Carbon-related deep states in compensated n-type and semi-insulating GaN : C and their influence on yellow luminescence." GAN, AIN, INN AND THEIR ALLOYS 831, 311-316 - 311-316.
  • Armstrong, A.; Arehart, A.; Green, D.; Speck, J. S.; Mishra, U. K.; Ringel, S. A., 2005, "A novel method to investigate defect states in MBE grown highly resistive GaN doped with C and Si." Physica Status Solidi C 2, no. 7, 2411-2414 - 2411-2414.


  • Armstrong,A; Arehart,A,R; Ringel,S,A; Moran,B; DenBaars,S,P; Mishra,U,K; Speck,J,S, 2003, "Identification of carbon-related bandgap states in GaN grown by MOCVD." GAN AND RELATED ALLOYS - 2003 798, 509-514 - 509-514.
  • Arehart,A,R; Poblenz,C; Heying,B; Speck,J,S; Mishra,U,K; DenBaars,S,P; Ringel,S,A, 2003, "Influence of growth parameters on the deep level spectrum in MBE-grown n-GaN." GAN AND RELATED ALLOYS - 2003 798, 735-740 - 735-740.

Papers in Proceedings


  • Sasikumar,A; Arehart,A; Ringel,S,A; Kaun,S; Wong,M,H; Mishra,U,K; Speck,J,S "Direct Correlation Between Specific Trap Formation and Electric Stress-induced Degradation in MBE-grown AlGaN/GaN HEMTs." in IEEE International Reliability Physics Symposium (IRPS). (1 2012).