Spectroscopic and Electrical Studies of Electronic and Optical Materials
The research in our lab involves studies of materials used in microelectronic, optical, and magnetic applications. In the area of
electronics, present and ongoing materials of interest are SiC and GaN. They are studied in order to deduce their potential in
high speed and/or high power electronic applications. Specifically, point defects in SiC wafers are examined using electron
paramagnetic resonance spectrosocopy (EPR) so that we may understand their role in achieving semi-insulating material. GaN, the
semiconductor which will form the basis of future lighting applications, contains several point defects critical to its application
in both light emitting diodes and high power devices. We address the chemical kinetics of these defects to assess the response of
the material to varying environments.
In collaboration with Physics colleague, Dr. Sergey Mirov, we study the structure of defects in potentially laser-active media.
At present, the work focuses on the role of Cr in achieving lasing in various II-VI and ternary compounds.
In collaboration with colleagues throughout the United States, we are studying complex oxides, materials which can be mated to
well-established electronics substrates such as SiC and produce multi-functional devices. Magnetic, optical, and electronic
operations are to be collected on one chip. With this goal, we are studying the Fe impurity in LiNbO3 and well as magnetic
impurities in SiC and GaN.
The experimental techniques used in this work, electron paramagnetic resonance (EPR) spectroscopy and a wide variety of electrical
measurements, are designed to address the low concentrations of isolated defects and impurities typical of technological-grade
electronic material. In addition, the low temperature EPR measurements are key to understanding the physical structure of the
impurities responsible for the properties of semi-insulating SiC,and other materials.
The EPR equipment, located in the solid state laboratory includes:
- Bruker Model EMX
9.6GHz EPR Spectrometer
- Air Products Closed-cycle Helium Refrigerator
- Oxford Instruments ESR900 Cryostat System
- Southbay Diamond Wheel
and polishing equipment
The equipment in the materials fabrication and analysis laboratory
- Keithley Model 82
Simultaneous CV System
- AC Conductance Instrumentation: 1 Hz to 1 MHz
- Bias Temperature Stress Instrumentation
- MMR Joule Thompson Refrigerator and high
- TENCOR Alpha-Step 500 Surface
- Ultra-dry Annealing Furnace and Moisture Monitor
- High Temperature Oxidation Furnace
- Metal Deposition System
- Southbay Wire Saw
Our research programs and students are supported in part by the Office of Naval Research and the National Science Foundation.
Recent Research Papers
- J. Dashdorj,
M.E. Zvanut, J.G. Harrison, K. Udwary, and T. Paskova, “Charge transfer in
semi-insulating Fe-doped GaN”, J. Appl. Phys. 112, 013712 (2012).
- M.E. Zvanut,
Y. Uprety, J. Dashdorj, M. Moseley and W. Alan Doolittle, “Passivation and
activation of Mg acceptors in heavily doped GaN”, J. Appl. Phys. 110,
- J. Dashdorj,
M.E. Zvanut, and L.J. Stanley, “Iron-related defect levels in SrTiO3
measured by photoelectron paramagnetic resonance spectroscopy”, J. Appl. Phys.
107, 083513 (2010).
Zvanut, G. Ngetich , J. Dashdorj, N.Y. Garces and E.R. Glaser,
“Photo-induced behavior of the VcCSi- pair
defect in 4H-SiC grown by physical vapor transport and halide chemical vapor
deposition”, J. Appl. Phys., 106, 64908 (2009).
- John Rozen,
Sarit Dhar, M. E. Zvanut, J. R. William, and L. C. Feldman, “Density of
interface states, electron traps, and hole traps as a function of the nitrogen
density in SiO2 on SiC” J. Appl. Phys. 105, 124506 (2009).
- J. van Tol,
G.W. Morley, S.Takahashi, D.R. McCamey, C. Boehme, and M.E. Zvanut,“High-field
phenomena of qubits”, Appl. Magn. Reson., 36 (2-4), 259-268 (2009
- J. Dashdorj, M.E. Zvanut, and J.G. Harrison,
“Measurements of optical cross sections of carbon vacancy in 4H-SiC by
time-dependent photo-electron paramagnetic resonance”, J. Appl. Phys. 104,
- M.E. Zvanut, S. Jeddy, E.
Towett, G.M. Janowski, C. Brooks, and D.
Schlom, “An annealing study of an oxygen vacancy
related defect in SrTiO3 substrates”, J. Appl. Phys. 104,
- Wonwoo Lee and M.E. Zvanut, “A study of deep defect levels in
semi-insulating SiC using optical admittance
spectroscopy”, J. Electron. Materials 36, 623 (2007).
- W.C. Mitchel, W.D. Mitchell, G. Landis, H.E. Smith, Wonwoo Lee, and M.E.
Zvanut, “Vanadium donor and acceptor levels in semi-insulating 4H- and 6H-SiC”,
J. Appl. Phys. 101, 013707 (2007).
- M.E. Zvanut, Wonwoo Lee, W.C. Mitchel, W.D. Mitchel, W.D. Mitchell, and G.
Landis, “The acceptor level for vanadium in 4H and 6H SiC”,
Physica B 376-377, 346 (2006).
- M.E. Zvanut,
Haiyan Wang, Mpumelelo
Richards, and V. V. Konovalov, “Observation of a
spin one native defect in as-grown high purity semi-insulating 4H
SiC”, J. Appl. Phys. 97, 123509 (2005).
D.M. Matlock, M.E. Zvanut, Haiyan Wang, Jeffrey R.
DiMaio, R.F. Davis, J.E. Van Nostrand, R.L. Henry,
Daniel Koleske, and Alma
Wickenden, “The effects of oxygen, nitrogen, and hydrogen annealing on Mg
acceptors in GaN as monitored by electron
paramagnetic resonance spectroscopy”, Journal of Electronic Materials 34,
- M.E. Zvanut,
Ustun R. Sunay, J. Dashdorj, W.R. Willoughby and A.A. Allerman, “Mg-hydrogen
interaction in AlGaN alloys”,
Proc. SPIE 8262, 82620L (2012).
- M.E. Zvanut, S.A. Thomas, and J. Dashdorj, “Intrinsic surface defects on 4H
SiC substrates”, edited by S.E. Saddow, E. Sanchez, F. Zhao, M. Dudley (Mater.
Res. Soc. Symp. Proc. Vol. 1246, Warrendale, PA, 2010) B03-03.
- M.E. Zvanut, G.
Ngetich, H.J. Chung, A.Y. Polyakov, M.
E. Glaser, and N. Garces, “Defect level of the
carbon vacancy carbon antisite pair center in SI 4H
SiC”, Mat. Sci. Forum 600-603,
- E.R. Glaser, N.Y. Garces, W.E. Carlos,
M.E. Zvanut, B. Magnusson, D.M. Hansen, G. Chung,and M.J. Loboda, “Infrared PL signatures of n-type bulk
substrates with nitrogen impurity concentration between 1016 and 1017
cm-3”, Mat. Sci. Forum 600-603,
- J. Dashdorj and M.E. Zvanut, “Study of chromium
impurities in SrTiO3 by photo-electron paramagnetic resonance
spectroscopy”, edited by J.F. Scott, V. Gopalan, M.
Okuyama, and M. Bibes
(Mater. Res. Soc. Symp. Proc. Volume 1034E,
Warrendale, PA, 2008), 1034-K10-19.
- M.E. Zvanut, G. Ngetich, H.J. Chung, A.Y.
Polyakov, and M. Skowronski,
“A study of vacancies and vacancy pair defects in 4H SiC
grown by halide chemical vapor deposition”, J. Mater. Sci:
Mat. in Electronics 19, 678 (2008).
- M.E. Zvanut and J. van Tol, “Nitrogen-related
point defect in 4H and 6H SiC”, Physica B
401-402, 73-76 (2007).
- Shehnaz Jeddy, Mary
Ellen Zvanut, Brian Einstein Lassiter, Gregg M. Janowski, and Leonard J.
Brillson “Themal stability of defects in substrates of
materials”, in Ferroelectrics and Multiferroics,
edited by V. Gopalan, J-P. Maria, M.
Fiebig, C-W. Nan (Mater. Res. Soc.
Symp. Proc. 966E, Warrendale, PA, 2007), 0966-T05-04.
- M.E. Zvanut, H.J. Chung, A.Y. Polyakov, and M.
Skowronski, “Point defects in 4H
SiC grown by halide
chemical vapor deposition”, Mat. Sci. Forum 556-557, 473 (2007).
- The Naval Research Laboratory
- Air Force Research Laboratory, Wright Patterson
- Auburn University
- University of Pittsburgh
- University of Alabama at Tuscaloosa
- General Electric Global Research