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Christou, Aris

Aris Christou
Professor
Director, Graduate Program in Reliability Engineering
Fellow, IEEE
2309A Chemical and Nuclear Engineering Building
Email: 
Phone: 
301-405-5208

News About This Professor

Education 

Ph.D., University of Pennsylvania, 1971

Research Interests 

Radiation effects in microelectronics, radiation hard design methodologies and physics of failure of compound semiconductors in space applications. Materials degradation, radiation induced defects in metals, corrosion and high pressure induced transformations in steels and iron alloys.

Background 

Prof Christou previously served as the Chair of the Department of Materials and Nuclear Engineering. Currently, he and his graduate students conduct research in Wide Band gap semiconductor materials for Power Electronics. Christou's research in Power Electronics Materials, devices and systems encompasses manufacturing and process science, extreme environments, and radiation effects in energy materials and devices. Christou’s group has also made significant contributions in photonic materials and devices, and optoelectronic device and component reliability. The third area of research is in flexible devices and materials for flexible displays. The emphasis has been on developing graphene interconnects for flexible electronics as well as investigating the mechanical, optical and electrical properties of graphene on polymer substrates.

Prof Christou’s research is also in the area of non lattice matched semiconductor systems based on his research of GaAs on Silicon. The research has now been extended to include optical interconnects as well as the co-integration of CMOS with analog GaAs devices. His work has now been extended to research of low temperature transistor action of amorphous silicon on flexible organic and non-organic substrates. Over the past 18 months, Christou has developed the highly reliable GaN Heterojunction GaN field effect transistor on both (100) and (111) silicon which will see application in microwave transmit-receive modules and now in the area of high voltage and high power electronics. The results published by his group over the last 12 months in the area of power electronics have made significant impact in further developing the wide band gap semiconductor device technology especially in the area of Vertical GaN HEMTs. Full Bio »

Teaching 

  • ENES100 : Introduction to Engineering Design
  • ENES 230: Introduction to Materials and Their Applications
  • ENMA 300: Introduction to Engineering Materials (formerly ENES 230)
  • ENMA 426/ENRE 447: Reliability of Materials
  • ENMA 463: Macroprocessing of Materials in Electronic Packaging
  • ENMA 626/ENRE600 : Reliability Engineering

Honors and Awards 

For a full list of honors and awards, please visit Professor Christou's web site

Books and Chapters 

Reliability of Compound Semiconductor Analogue Microwave Integrated Circuits
Published by RIAC, December 2006.

Reliability of High Temperature Electronics, Second Edition
Published by RIAC, December 2006.

Photonic Materials, Devices and Reliability, Second Edition
Published by RIAC, December 2006.
ISBN-13: 9781933904047

Lectures in: Photonic Materials, Devices and Reliability
Published by Center for Reliability Engineering, 2003.
ISBN 0-9652669-7-4

Introduction to the Physics of Materials
Published by CTRS, Beacon Press, 1999.
ISBN 0-9652669-9-0

Reliability of High Temperature Electronics
Published by CTRS, Printed by Beacon Press, 1996.
ISBN 0-9652669

Reliability of GaAs Monolithic Integrated Circuits
Published by John Wiley and Sons, October 1992; second edition 1995.

Integrating Reliability into Microcircuit Manufacturing
Published by John Wiley, 1994.
ISBN 0-4719440-7-6

Electromigration and Electronic Device Degradation
Aris Christou (Editor)
Published by John Wiley, 1993.
ISBN: 0-471-58489-4

Selected Publications 

For a more extensive list of selected publications, please visit Proessor Christou's web site
For the entire publication list, please see Professor Christou's C.V. (PDF)


Y. Lu, A. Christou, “Life Prediction of IGBT Modules Based on the Method of Particle Filters,” Microelectronics Reliability. (Accepted for  June 2018)

D.I. Shahin, M.J. Tadjer, V.D. Wheeler, A.D. Koehler, T.J. Anderson, C.R. Eddy, Jr., A. Christou, “Electrical Characterization of ALD HfO2 High-k Dielectrics on (-201) β-Ga2O3,” Applied Physics Letters 112, 042107 (2018).

D.I. Shahin, T.J. Anderson, A. Christou, “Achieving Vertical Trench-Gate GaN MOSFETs Via Process Optimization,” ECS Transactions 80 [7], 139-145 (2017).

D.I. Shahin, A. Christou, J.E. Butler “High Power Diamond Devices with 2-D Transport Channels,” ECS Transactions 80 [7], 197-201 (2017).

V.D. Wheeler, T.J. Anderson, S. Ahn, D.I. Shahin, M.J. Tadjer, A.D. Koehler, K.D. Hobart, F. Ren, F.J. Kub, A. Christou, C.R. Eddy, Jr., “ALD TiN Schottky Gates for Improved Electrical and Thermal Stability in III-N Devices,” ECS Transactions 80 [3], 17-25 (2017).

Y. Lu and A. Christou, "Lifetime Estimation of Insulated Gate Bipolar Transistor Modules Using Two-Step Bayesian Estimation," in IEEE Transactions on Device and Materials Reliability, vol. 17, no. 2, pp. 414-421, J (2017).

T.J. Anderson, K.D. Hobart, J.D. Greenlee, D.I. Shahin, A.D. Koehler, E.A. Imhoff, R.L. Myers-Ward, A. Christou, F.J. Kub, “UV and EUV Detectors Based on the Graphene/SiC Heterojunction”, Submitted to Electronic Letters, 2014.

Gary Paradee, Tom Martin, Aris Christou, “Fatigue Properties of Graphene on Flexible Substrates”, IEEE Transactions on Device and Materials Reliability, December 2014.

Gary Paradee, Tom Martin and Aris Christou, “Fatigue Properties of Uniform and Patterned ITO on Flexible Substrates,” J. Microelectronics Reliability, Accepted 2014 and to be published 2015.

Gary Paradee, Eric Bailey and A. Christou, “Stress relaxation behavior and low cycle fatigue behavior of bulk SAC 305,” J. Mater. Sci. Electron (2014) 25:4122-4128.

Gary Paradee, Tom Martin, Aris Christou, “Fatigue Properties of Graphene on Flexible Substrates”, IEEE Transactions on Device and Materials Reliability, December 2014.

A. Christou, “Process-Reliability Relationships in GaN and GaAs Field Effect Transistors and HFETs”, Compound Semiconductor Manufacturing Technology, Digest_2013, pp 391-394.

Kaushik Chatterjee, Mohammad Modarres and Joseph B. Bernstein. "Fifty Years of Physics of Failure" (PDF), Journal of the Reliability Informaiton Analysis Center, January 2012.

M. Sawant, and A. Christou. "Failure modes and effects criticality analysis and accelerated life testing of LEDs for medical applications." Solid-State Electronics, (2012) 78, 39–45.

Martin Peckerar, Thomas Martin, and Aris Christou. http://christou.umd.edu/publications/conferences.html"Nanoparticle Technology for Power Integration With Flexible Substrates."

Christou, A., & Fantini, F. "Introduction to the special issue on GaN and related nitride compound device reliability." IEEE Transactions on Device and Materials Reliability, (2008) 8(2), 239-239.

Christou, A. "Monte Carlo Reliability Model for Microwave Monolithic Integrated Circuits." Quality and Reliability Engineering International, (2008) 24(3), 315-329.

S. Yang, A. Christou, “Failure Model for Silver Electromigration,” IEEE Trans Materials, Device Reliability, Vol2,  Feb 2007.

S. Yang, J.Wu, A. Christou, “Initial Stages of Silver Electrochemical Migration Degradation,” Microelectronics Reliability vol.46 (2006) 1915-1921.

C.C. Zhang, Aris Christou, “Reliability of Leadless Interconnects in GaAs ASICS”, J. of RIAC, 2006, No.2, 20-26.

Ahangir Alam, Andrei E. Botchkarev, James A. Griffin, John M. Zavada, Aristos Christou and S. Noor Mohammad, “Optical properties of MBE-grown GaAs1-xNx alloys”, Phil Mag, 1121-1134, 2006.

S. J. Chang, C. F. Shen, S. C. Shei, C. S. Chang, W. S. Chen, T. K. Ko, J.K.Shei and Y. S. Sun, "Highly Reliable Nitride-Based LEDs with Internal ESD Protection Diodes" (PDF), IEEE Transactions on Device and Materials Reliability, November 2005.

L.Mohaddes-Ardahilli, L. Martinez-Miranda, L. Salamanca-Riba, A. Christou, William Bentley and M. Al- Sheikhley, “Preferred Orientation of DNA Olionucleotide probes on the (2x4) Reconstructed Surface of (001) GaAs,” J Appl. Physics Vol 95, No. 11, Part 1 (6021-6024), June 2004.

Mohamad Al-Sheikhley, D. Sweet, Lourdes Salamanca-Riba, B. Varughese, J. Silverman, Aris Christou and William Bentley, “Radiation-Induced Failure Mechanisms of GaAs–Based Biochips,” IEEE Transactions on Device and Materials Reliability, vol. 4, No. 2 (192-197), June 2004.

C. Zhang, P. Yalamanchili, M. Al-Sheikhley and A. Christou, Metal Migration in Epoxy Encapsulated ECL Devices, 2004 ESREF, Oct. 2004.

L.Mohaddes-Ardahilli, L. Martinez-Miranda, J. Silverman, A. Christou, L. Salamanca- Riba and M. Al- Sheikhley, “Attachment of DNA Probes on GaAs Surfaces”, Appl. Physics Lettrs, 83, No. 1, pp. 192-194 (2003).

N. Strifas, P. Yalamanchili, A. Christou, “Reliability Model for Polyimide-Metal Interconnect Shorts,” Qual and Reliability Int. 20:1-13 (2004).

M. Linnik and A. Christou, “Calculations of optical properties for Quartenary III-V semiconductor alloys in the transparent region and above” (PDF), Physica B, 318, pp 140-161 (2002). Abstract »

Selected Presentations 

For a more extensive list of selected presentations, please visit Proessor Christou's web site

D.I. Shahin, K.K. Kovi, A. Thapa, Y. Lu, I. Ponomarev, J.E. Butler, A. Christou, “Fabrication and Characterization of Diamond FETs with 2D Conducting Channels,” 2018 International Workshop on Compound Semiconductor Manufacturing Technology, May 6-11, 2018, Austin, TX. (Accepted)

D.I. Shahin, K.K. Kovi, A. Thapa, Y. Lu, I. Ponomarev, J.E. Butler, A. Christou, ``Diamond Electronics with 2-D Transport Channel,'' 2018 Lawrence Symposium on Epitaxy, February 18-21, 2018, Scottsdale, AZ (Invited)

D.I. Shahin, K. Kovi, M. Yung, Y. Lu, A. Yuan, A. Auerbach, A. Thapa, I. Ponomarev, J.E. Butler, A. Christou, “Radiation Hardness of Hydrogen-Terminated Diamond Transistor and Diode Structures,” 2017 Materials Research Society Fall Meeting and Exhibit, November 26-December 1, 2017, Boston, MA.

D.I. Shahin, T.J. Anderson, A. Christou, “Achieving Vertical Trench-Gate GaN MOSFETs Via Process Optimization,” 232nd Electrochemical Society Meeting, October 1-6, 2017, National Harbor, MD (Invited).

D.I. Shahin, A. Christou, J.E. Butler “High Power Diamond Devices with 2-D Transport Channels,” 232nd Electrochemical Society Meeting, October 1-6, 2017, National Harbor, MD (Invited).

V.D. Wheeler, T.J. Anderson, S. Ahn, D.I. Shahin, M.J. Tadjer, A.D. Koehler, K.D. Hobart, F. Ren, F.J. Kub, A. Christou, C.R. Eddy, Jr., “ALD TiN Schottky Gates for Improved Electrical and Thermal Stability in III-N Devices,” 232nd Electrochemical Society Meeting, October 1-6, 2017, National Harbor, MD.

D.I. Shahin, M.J. Tadjer, V.D. Wheeler, A.D. Koehler, A. Christou, “Characterization of ZrO2 and HfO2 Dielectrics Deposited by Thermal ALD on β-Ga2O3 Substrates,” 2nd International Workshop on Gallium Oxide and Related Materials, September 12-15, 2017, Parma, Italy.

D.I. Shahin, M.J. Tadjer, V.D. Wheeler, T.J. Anderson, A.D. Koehler, K.D. Hobart, C.R. Eddy, Jr., F.J. Kub, A. Christou, “Characterization of ZrO2 and HfO2 MOS Capacitors Deposited by ALD on (-201) β-Ga2O3 Substrates,” 59th Electronic Materials Conference, June 28-30, 2017, South Bend, IN.

D.I. Shahin, T.J. Anderson, V.D. Wheeler, M.J. Tadjer, A. Christou, “ALD High-k ZrO2 Dielectrics for Wide and Ultra-Wide Bandgap Semiconductor Devices,” 2017 Workshop on Compound Semiconductor Devices and Integrated Circuits held in Europe (WOCSDICE), May 21-24, 2017, Las Palmas de Gran Canaria, Spain.

D.I. Shahin, T.J. Anderson, V.D. Wheeler. M.J. Tadjer, L.E. Luna, A.D. Koehler, K.D. Hobart, C.R. Eddy, Jr., F.J. Kub, A. Christou, “Characterization of ALD High-k Dielectrics in GaN and Ga2O3 Metal-Oxide-Semiconductor Systems,” 2017 International Conf. on Compound Semiconductor Manufacturing Technology, May 22-25, 2017, Indian Wells, CA.

C. Eddy, Jr., V. Wheeler, D.I. Shahin, T. Anderson, M. Tadjer, A. Koehler, K. Hobart, A. Christou, F. Kub. “ZrO2 as a High-k Gate Dielectric for Enhancement-mode AlGaN/GaN MOS HEMTs,” 44th Conference on the Physics and Chemistry of Surfaces, January 15-19, 2017, Santa Fe, NM.

Y. Lu, A. Christou, “Particle-filter-based Prognostics of IGBT Modules Due to Packaging-related Failure”, CALCE Fall 2017 Technical Review.

Y. Lu, A. Christou, “Prognostics of Insulated Gate Bipolar Transistor Modules Under Power Cycling Conditions based on    Particle Filtering”, 2017 MRS Fall Meeting & Exhibits.David Shahin, and A. Christou, “GaN/Si(111) Device Defects and Degradation Mechanisms,” ECS Transactions, 64(7) 203-211 (2014).


Krishna Shenai, Aris Christou, Michael Dudley, Balaji Ragothamachar and Rajendra Singh, “Crystal Defects in Wide Bandgap Semiconductors,” ECS Transactions, 61(4) 283-293 (2014).

A. Christou, Krishna Shenai and  Dimitri Pavlidis, “Crystal Defects in Wide Bandgap Semiconductors and Effects on Device Performance,” Proceedings WOCSDICE, June 2014.

Aris Christou, P. McCuskey and A. Dasgupta, “ Physics of Failure and Reliability of Power Electronics Devices”, p. 1926, Proceedings of 224th ECS Meeting, 2013 The Electrochemical Society.

A. Christou, “GaN MESFETs and HFETs Processing Technology and Reliability Relationships, and Robust Wide-band gap Power Semiconductor Devices”, Micro-Nanotechnology, Digest of Presentations, 2013.

A. Christou and D. Pavlidis, (Keynote Talk) “Control of Surfaces and Interfaces for Enhanced Performance and Reliability of Wide Bandgap Semiconductor Devices” Technical Digest of International Conference on Intergranular and Interphase Boundaries in Materials 2013, Halkidiki Greece, Digest of Presentations.

A. Christou. "GaAs and GaN MESFETs and HFETs Processing Technology and Reliability Relationships, A Review" (PDF) Plenary Lecture. Micro- and Nanoelectronics Conference, October 5th, Heraklio, Crete, Greece. (2012)

M. Sawant and A. Christou,"A Bayes Approach and Criticality Analysis for Reliability Prediction of AlGaInP Light Emitting Diodes" (PDF), Reliability Of Compound Semiconductors Workshop (ROCS 2012), April 23, Boston, Mass. (2012)

Zahra Mohaghegh, Mohammad Modarres and Aris Christou, "Physics-Based Common Cause Failure Modeling in Probabilistic Risk Analysis: A Mechanistic Perspective" (PDF), Proceedings of the ASME 2011 Power Conference, POWER2011, July 12-14, Denver, Colorado, USA (2011)

Martin Peckerar, Thomas Martin and Aris Christou, "Flexible Displays With Nanostructured Integrated Power Sources" (PDF), IC4N 2011, June 26-30, Crete, Greece (2011)

Martin Peckerar, Thomas Martin and Aris Christou, "Nanoparticle Technology for Power Integration With Flexible Substrates" (PDF), Proceedings of the IC4N 2011, June 26-30, Crete, Greece (2011)

M. Sawant and A. Christou, "Failure Modes and Effects Criticality Analysis and Accelerated Life Testing of LEDs for Medical Applications" (PDF), ISDRS 2011, December 7-9, College Park, MD (2011)

S. Salemi and A. Christou, "Charge Control Analysis of Gallium Nitride Semiconductor Heterostructures and Comparison with GaAs HFET Failure Mechanisms" (PDF), WOCSDICE 2008, May 18-21, Leuven, Belgium (2008)

M. Linnick, Chichang Zhang and A. Christou, “Dielectric Constants for AlGaInAs Quartenary Semiconductor Alloys Grown by MBE for VCSEL Bragg Mirror Applications”, in The Physics and Challenges for Integrated Optics Symposium, MS&T 2005, pp. 23-31

M. Al-Sheikhley, A. Christou, “The Limitations of GaAs/DNA Based Bio-Memory and Sensing Device,” WOCSDICE 2005, pp. 143-148, Cardiff, Wales, UK (2005)

A. Christou, “Advances in Engineering Education: Building alliances With Professional Societies”, Proceedings of the International Conference on Engineering Education, ISBN: 1562-3580, July 2005, Gliwice, Poland

Materials Education for the 21st Century Workforce: The 18th Biennial Conference on National Materials Policy. May 24-25, National Academies’ Keck Center, Washington, DC (2004) Dr. Christou chaired the conference–Read his Opening Remarks (PDF)

CC Zhang, P. Yalamanchili, M. Al-Sheikhley and A. Christou, "Metal Migration in Epoxy Encapsulated ECL Devices," 2004, Proceedings ESREF 2004

A. Christou and M. Al-Sheikhley, “Hydridization of DNA on GaAs by VCSEL Source 980nm Photons, MRS 2003 Proceedings Dec 1-3 Boston (2003)

Agis A. Iliadis and A. Christou, "Design and Development of Short and Long Wavelength Infrared Vertical Cavity Surface Emitting Lasers,"(PDF) Invited Paper: 2003 Photonics West, Jan 29-Feb 03, 2003 Paper OE15-29-02

Related News 

Christou’s Group presents short course, research at CS ManTech
Christou and students travel to Austin, TX to present short course and diamond power electronics research May 11, 2018

MSE Grad Student, David Shahin, Receives Award for Diamond Tech Research
Shahin’s presentation at the MRS Fall 2017 Meeting took second place. December 11, 2017

MSE Professor Aristos Christou Elevated to IEEE 'Life Fellow'
Christou received this honor based on significant accomplishments and advancements to the engineering field. May 2, 2017

Professor Aristos Christou Leads Research of Diamond Electronics
Carbon electronics that are built around graphene will now include diamond. December 1, 2016

MSE Researchers Shahin and Christou Published in Applied Physics Express
David Shahin and Aris Christou collaborate with U.S. Naval Research Lab on high-electron-mobility transistors. July 21, 2016

Shahin Receives CALCE Best Presenter Award
MSE grad student David Shahin named Fall 2015 Electronic Products and Systems Consortium Technical Review Best Student Presenter December 15, 2015

Shahin Among Top 2% of UMD Graduate Assistants
Graduate School honors Ph.D. student with 2015 Outstanding Graduate Assistant Award May 7, 2015

Bailey Awarded NSF Graduate Research Fellowship
Four materials science students receive Honorable Mentions. April 21, 2015

Shahin Wins ASEE Naval Research Internship
NREIP Program selects MSE grad student for summer program. March 12, 2015

Christou Joins Md. Delegation to European Offshore Wind Energy Conference
Professor will present paper on predictive modeling of grid reliability. March 2, 2015

Undergrad Among First to Map Solar Cell Parameters at Sub-Micron Resolution
Bailey receives second SEEDS Fellowship, will conduct work in Leite Lab. November 12, 2014

Workshop on Defects in Wide Band Gap Semiconductors Sept. 23
Abstracts due July 28 July 10, 2014

Offshore Wind Energy and Reliability
Clark School professors support the State of Maryland's efforts to establish a resilient wind farm. May 25, 2014

Exploring Offshore Wind Energy for Maryland
Md. Higher Education Commission funds Clark School study of reliability, cost-effectiveness of wind-generated energy. September 10, 2013

Christou Invited to Discuss Wide Bandgap Semiconductors, Physics-of-Failure
Professor will be featured speaker in summer conferences in Greece. April 22, 2013

Christou Receives IEEE Service Award
Professor recognized for pioneering work on high-impact journal. December 17, 2012

Workshop on Wide Bandgap Power Semiconductors Stresses Need for Commercial Development
Participants from academia, government and industry discuss manufacturing initiative, new consortium to address challenges. December 3, 2012

Christou Organizes Workshop on Wide Bandgap Semiconductors
Event to be held Oct. 23 at Kim Engineering Building. October 17, 2012

Christou to Deliver Keynote at Micro&Nano 2012
Professor will also be recognized for contributions to semiconductor research. September 14, 2012

Christou Tapped for Expert Panel in Condensed Matter Physics
New program will fund research in Greece. January 26, 2012

Christou Appears on "Platts Energy Week"
Professor discusses rise of applicants to nuclear engineering programs. September 7, 2010

NRC Funds Development of New Grad-Level Corrosion Courses
Ankem, Christou, and Moderres to create new modules for nuclear, reliability, and sustainability engineering programs. June 14, 2010

NRC Collaboration Helps Bring Nuclear Engineering Education Online
Nuclear Engineering graduate degrees (M.Eng. and Graduate Certificate) available 100% online. June 15, 2009

Christou Designs Better Lasers for Threat Detection
New lasers are tunable, span longer wavelengths. April 16, 2008

Christou Receives ASM Award
International society recognizes original research, leadership. March 28, 2007

Materials Camp Will Help Teachers Innovate
Sessions seek to improve K-12 education, inspire students. June 22, 2006

Professor Christou hosts the Federation of Materials Societies Award Reception
Prof. Christou outlined the directions to be take by FMS in 2006 January 19, 2006