Dr. Jae-Hyun Ryou

Professor of Mechanical & Aerospace Engineering

Office Location N220 Engineering Building 1

Phone 713-743-0858

Fax 713-743-4503

Email jryou [at] uh.edu

Website Ryou Research Group

Education

Ph.D., The University of Texas at Austin

Professional Experience

Associate Professor, Department of Mechanical and Aerospace Engineering, University of Houston

Assistant Professor, Department of Mechanical Engineering, University of Houston

Research Engineer, Center for Compound Semiconductors, Georgia Institute of Technology

Research Scientist, Honeywell Technology Center and Honeywell VCSEL Optical Products, Honeywell International

Professional and Scientific Affiliations

Institute of Electrical and Electronics Engineers (IEEE)

Optical Society of America (Optica)

Materials Research Society (MRS)

Courses Taught

MECE2334 Thermodynamics

MECE2336 Mechanics I: Statics

MECE3345 Materials Science

MECE3245 Materials Science Laboratory

MECE5397/6365 Semiconductor Materials and Photonic and Electronic Devices

MECE5397/6397 Functional Engineering Materials: Science and Applications

MECE6361 Mechanical Properties of Materials

MECE6364 Phase Transformations in Materials

Research Interests

Dr. Ryou's research interests are in semiconductor materials and devices for electronic, photonic, sensing, and energy applications. Specifically, he and his team study (1) heteroepitaxy of semiconductor thin films, (2) fundamental device physics of flexible electronics and photonics, (3) energy harvesting and conversion devices, (4) personal healthcare sensors, (5) extreme-environment electronics and sensors by modeling, epitaxial growth, characterizations, and fabrication development.

Some articles about Dr. Ryou and his colleagues' research:

Engineering Applications

Flexible electronics, flexible display, solid-state lighting, photovoltaic and mechanical energy harvesting, self-powered systems, and wearable and bio-compatible power sources and systems

Awards & Honors

Awards for Excellence in Research, Scholarship and Creative Activity, University of Houston, 2024

W. T. Kittinger Teaching Excellence Award, University of Houston Cullen College of Engineering, 2022

50-in-5 Scholars, University of Houston, 2022, 2020, 2019, 2018

Air Force Summer Faculty Fellowship, Air Force Office of Scientific Research, 2023, 2022

Rising Innovator Award, University of Houston Cullen College of Engineering, 2020

Senior Faculty Research Excellence Award, University of Houston Cullen College of Engineering, 2019

Outstanding Reviewer Award, Acta Materialia, 2019

Teaching Excellence Award, University of Houston Cullen College of Engineering, 2017

Roger P. Webb Research Spotlight Award, Georgia Institute of Technology School of Electrical and Computer Engineering, 2011

Professional Activities

Guest Co-Editor, Nanomaterials, Special Issue: III-N Based Semiconductor Nanomaterials for Photonic and Electronic Devices, 2022.

Associate Editor, Optics Express, 2010 – 2016

Guest Co-Editor, Special issue of Physica Status Solidi C: Current Topics in Solid-State Physics, 2015

Guest Co-Editor, Energy Express, Focus Issue: Optics in LEDs for Lighting, 2011

Organizing Committee Member, Electronic Materials Conference (EMC), 2021 – present

Committee Member, EDTM 2023 (7th IEEE Electron Devices Technology and Manufacturing Conference), 2023

Invited Organizer, EMC 2021 (63rd Electronic Materials Conference), 2021

Invited Organizer, EMC 2020 (62nd Electronic Materials Conference), 2020

Program Committee Member, ICCGE 19/OMVPE 19 (19th International Conference on Crystal Growth and Epitaxy/19th US Biennial Workshop on Organometallic Vapor Phase Epitaxy), 2019

Program Committee Member, ISGN-6 (6th International Symposium on Growth of III-Nitrides), 2015

Co-Chair, Publications Committee, ISGN-5 (5th International Symposium on Growth of III-Nitrides), 2014

External Link(s) to Publications Listing

Google Scholar

Selected Publications

N.-I. Kim, J. Chen, W. Wang, M. Moradnia, S. Pouladi, J.-Y. Kim, M.-K. Kwon, and J.-H. Ryou, "Skin-attached piezoelectric sensor arrays for continuous monitoring of oculomotor movements," Adv. Healthc. Mater. 13 (15), 2303581-1‒11 (2024). [Featured frontispiece article, in issue 15 of volume 13 (Jun. 2024)]
Y. G. Kim, S. Pouladi, N.-I. Kim, M. Moradnia, J. Kim, K.-H. Lee, and J.-H. Ryou, "Inverted n-p junction 940-nm VCSEL arrays consisting of 875 devices on p-GaAs substrate," Electron. Lett. 60 (9), e13166-1‒3 (2024).
M. Aqib, S. Pouladi, M. Moradnia, R. P. Rajesh Kumar, N.-I. Kim, and J.-H. Ryou, "Strain accumulation and relaxation on crack formation in epitaxial AlN film on Si (111) substrate," Appl. Phys. Lett. 124 (4), 042109-1‒6 (2024).
N.-I. Kim, M. Yarali, M. Aqib, M. Moradnia, C.-H. Liao, F. AlQatari, M. Nong, X. Li, and J.-H. Ryou, "Piezoelectric sensor operating at very high temperatures and in extreme environments made of flexible ultrawide-bandgap single-crystalline AlN thin films," Adv. Funct. Mater. 33, 2212538-1‒10 (2023). [Featured front-cover article, in issue 10 of volume 33 (March 2023)]
M. Moradnia, S. Pouladi, J. Chen, N.-I. Kim, O. Aigbe, and J.-H. Ryou*, "Thermodynamic analysis of hybrid chemical vapor deposition of transition-metal-alloyed group-III-nitride ScAlN piezoelectric semiconductor films," Cryst. Growth Des. 22 (4), 2239−2247 (2022). [Featured supplementary-cover article in issue 5 of volume 22 (April 2022)] [Also Featured in a special issue of Women Researchers at the Forefront of Crystal Engineering]
J.-H. Ryou and S. Choi, "All-around diamond for cooling high-power devices," Nat. Electron. 5, 834‒835 (2022).
S. Pouladi, C. Favela, W. Wang, M. Moradnia, S. Shervin, N.-I. Kim, J. Chen, S. Sharma, G. Yang, M.-C. Nguyen, R. Choi, J. Kim, A. Fedorenko, B. Bogner, J. Bao, S. Hubbard, V. Selvamanickam, and J.-H. Ryou, "Significant improvement of conversion efficiency by passivation of low-angle grain boundaries in flexible low-cost single-crystal-like GaAs thin-film solar cells directly deposited on metal tape," Sol. Energy Mater. Sol. Cells 243, 111791-1‒9 (2022).
S. Shervin, M. Moradnia, K. Alam, T. Tang, M.-H. Ji, J. Chen, S. Pouladi, T. Detchprohm, R. Forrest, J. Bao, R. D. Dupuis, and J.-H. Ryou, "Flexible single-crystalline GaN substrate by direct deposition of III-N thin films on polycrystalline metal tape," J. Mater. Chem. C 9 (7), 2243−2251 (2021). [Featured front-cover article in issue 7 of volume 9 (February 2021)]
N.-I. Kim, J. Chen, W. Wang, M. Moradnia, S. Pouladi, J. Y. Kim, M.-K. Kwon, X. Li, and J.-H. Ryou, "Highly-sensitive skin-attachable self-powered eye-movement sensor using flexible non-hazardous piezoelectric thin film," Adv. Funct. Mater. 31 (8), 2008242-1−11 (2021).
W. Wang, J. Chen, J. S. Lundh, S. Shervin, S. K. Oh, S. Pouladi, Z. Rao, J. Y. Kim, M.-K. Kwon, X. Li, S. Choi, and J.-H. Ryou, "Modulation of the 2-dimensional electron gas channel in flexible AlGaN/GaN high-electron-mobility transistors by mechanical bending," Appl. Phys. Lett. 116 (12), 123501-1–5 (2020). [Featured editor’s pick article in issue 12 of volume 116 (March 2020)]
J. Chen, H. Liu, W. Wang, N. Nabulsi, W. Zhao, J. Y. Kim, M.-K. Kwon, and J.-H. Ryou, "High durable, biocompatible and flexible piezoelectric pulse sensor using III-N thin film," Adv. Funct. Mater. 29 (37), 1903162-1–10 (2019). [Featured back-cover article in issue 37 of volume 29 (September 2019)]
W. Wang, S. M. Lee, S. Pouladi, J. Chen, S. Shervin, S. Yoon, J. H. Yum, E. S. Larsen, C. W. Bielawski, B. Chatterjee, S. Choi, J. Oh, and J.-H. Ryou, "Polarization modulation effect of BeO on AlGaN/GaN high-electron-mobility transistors," Appl. Phys. Lett. 115 (10), 103502-1–5 (2019). [Featured editor’s pick article in issue 10 of volume 115 (September 2019)]
S. Pouladi, M. Asadirad, S. K. Oh, S. Shervin, J. Chen, W. Wang, C.-N. Manh, R. Choi, J. Kim, D. Khatiwada, M. Rathi, P. Dutta, V. Selvamanickam, and J.-H. Ryou, "Effects of grain boundaries on conversion efficiencies of single-crystal-like GaAs thin-film solar cells directly deposited on flexible metal tapes," Sol. Energy Mater. Sol. Cells 199, 122‒128 (2019).
(Invited review paper) S. K Oh, J. S. Lundh, S. Shervin, B. Chatterjee, D. K. Lee, S. Choi, J. S. Kwak, and J.-H. Ryou, "Thermal management and characterization of high-power wide-bandgap semiconductor electronic and photonic devices in automotive applications," J. Electron. Packaging 141, 020801-1‒17 (2019).
P. Dutta, M. Rathi, D. Khatiwada, S. Sun, Y. Yao, B. Yu, S. Reed, M. Kacharia, J. Martinez, A. Litvinchuk, X. Pasala, S. Pouladi, B. Eslami, J.-H. Ryou, H. Ghasemi, P. Ahrenkiel, S. M. Hubbard, and V. Selvamanickam, "Flexible GaAs solar cells on roll-to-roll processed epitaxial Ge films on metal foils: a route towards low-cost and high-performance III-V photovoltaics," Energy Environ. Sci. 12, 756‒766 (2019).
J. Chen, S. K. Oh, N. Nabulsi, H. Johnson, W. Wang, and J.-H. Ryou, "Biocompatible and sustainable power supply for self-powered wearable and implantable electronics using flexible III-nitride thin-film-based piezoelectric generator," Nano Energy 57, 670‒679 (2019).
S. Pouladi, M. Rathi, D. Khatiwada, M. Asadirad, S. K. Oh, P. Dutta, Y. Yao, Y. Gao, S. Sun, Y. Li, S. Shervin, K. H. Lee, V. Selvamanickam, and J.-H. Ryou, "High-efficiency flexible III-V thin-film photovoltaic solar cells based on single-crystal-like thin-film directly grown on metallic tapes," Prog. Photovoltaics: Res. Appl. 27 (1), 30‒36 (2019). [Featured cover article in issue 1 of volume 27 (January 2019)]
K. J. Son, T. K. Kim, Y.-J. Cha, S. K. Oh, S.-J. You, J.-H. Ryou, and J. S. Kwak, "Impact of electron flux on plasma damage-free sputtering of ultrathin indium-tin-oxide contact layer on p-GaN for InGaN/GaN light-emitting diodes," Adv. Sci. 5 (2), 1700637-1–10 (2018).
S. Shervin, S. K. Oh, H. J. Park, K.-H. Lee, M. Asadirad, S. H. Kim, J. Kim, S. Pouladi, S.-N. Lee, X. Li, J. S. Kwak, and J.-H. Ryou, "Flexible deep-ultraviolet light-emitting diodes for significant improvement of quantum efficiencies by external bending," J. Phys. D: Appl. Phys. 51 (10), 105105-1–7 (2018).
W. Lee, S. Muhammad, T. Kim, H. Kim, E. Lee, M. Jeong, S. Son, J.-H. Ryou, and W. S. Yoon, "New insight into Ni-rich layered structure for next-generation Li rechargeable batteries," Adv. Energy Mater. 8 (4), 1701788-1–12 (2018). [Featured cover article in issue 4 of volume 8 (February 2018)]
S. M. Lee, J. H. Yum, S. Yoon, E. S. Larsen, W. C. Lee, S. K. Kim, S. Shervin, W. Wang, J.-H. Ryou, C. W. Bielawski, and J. Oh, "Atomic layer deposition of single-crystalline BeO epitaxially grown on GaN substrates," ACS Appl. Mater. Interfaces 9 (48), 41973–41979 (2017).
S. K. Oh, M. U. Cho, J. Dallas, T. Jang, D. G. Lee, S. Pouladi, J. Chen, W. Wang, S. Shervin, H. Kim, S. Shin, S. Choi, J. S. Kwak, and J.-H. Ryou, "High-power flexible AlGaN/GaN heterostructure field-effect transistors with negative differential conductivity suppression," Appl. Phys. Lett. 111 (13), 133501-1–5 (2017).
W. Wang, S. Shervin, S. K. Oh, J. Chen, Y. Huai, S. Pouladi, H. Kim, S.-N. Lee, and J.-H. Ryou, "Flexible AlGaInN/GaN heterostructures for high-hole-mobility transistors," IEEE Electron Device Lett. 38 (8), 1086–1089 (2017).
M. Asadirad, S. Pouladi, S. Shervin, S. K. Oh, K. H. Lee, J. Kim, S.-N. Lee, Y. Gao, P. Dutta, V. Selvamanickam, and J.-H. Ryou, "Numerical simulation for operation of flexible thin-film transistors with bending," IEEE Electron Device Lett. 38 (2), 217–220 (2017).
M. Asadirad, Y. Gao, P. Dutta, Y. Yao, S. Shervin, S. Sun, S. Ravipati, S.-H. Kim, K. H. Lee, V. Selvamanickam, and J.-H. Ryou, "High-performance flexible thin-film transistors based on single-crystal-like germanium on glass," Adv. Electron. Mater. 2 (8), 1600041-1–7 (2016). [Featured frontispiece article in issue 8 of volume 2 (August 2016)]
S. Shervin, S.-H. Kim, M. Asadirad, S. Yu. Kapov, D. Zimina, and J.-H. Ryou, "Bendable III-N visible light-emitting diodes beyond mechanical flexibility: Theoretical study on quantum efficiency improvement and color tunability by external strain," ACS Photon. 3 (3), 486–493 (2016). [Featured cover article in issue 3 of volume 3 (March 2016)]
J. Kim, M.-H. Ji, T. Detchprohm, R. D. Dupuis, A. M. Fischer, F. A. Ponce, and J.-H. Ryou, "Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition," J. Appl. Phys. 118 (12), 125303-1–6 (2015).
K. H. Lee, H. J. Park, S. H. Kim, M. Asadirad, Y.-T. Moon, J. S. Kwak, and J.-H. Ryou, "Light extraction efficiency control in AlGaN-based deep-ultraviolet flip-chip light-emitting diodes: A comparison to visible flip-chip light-emitting diodes," Opt. Express 23 (16), 20340–20349 (2015).
Y.-J. Yu, K. S. Kim, J. Nam, S. R. Kwon, H. Byun, K. Lee, J.-H. Ryou, R. D. Dupuis, J. Kim, G. Ahn, S. Ryu, M.-Y. Ryu, and J. S. Kim, "Temperature-dependent resonance energy transfer from semiconductor quantum wells to graphene," Nano Lett. 15 (2), 896–902 (2015).
S. Shervin, S.-H. Kim, M. Asadirad, S. Ravipati, K.-H. Lee, K. Bulashevich, and J.-H. Ryou, "Strain-effect transistors: Theoretical study on the effects of external strain on III-nitride high-electron-mobility transistors on flexible substrates," Appl. Phys. Lett. 107 (19), 193504-1–5 (2015).

Books / Book Chapters

Theeradetch Detchprohm, Jae-Hyun Ryou, Xiaohang Li, and Russell D. Dupuis, "Chapter 14. Future aspects of MOCVD technology," Metalorganic Vapor Phase Epitaxy (MOVPE): Growth, Materials Properties and Applications, S. J. C. Irvine and P. Capper, Ed., Wiley, Hoboken, New Jersey, U.S.A. (2019) (ISBN-12: 978-11193130).
Jae-Hyun Ryou and Wonseok Lee, "Chapter 3. GaN on sapphire substrates for visible light-emitting diodes," Nitride Semiconductor Light-Emitting Diodes (LEDs): Materials, Technologies, and Applications, 2nd Ed., J. J Huang, H.-C. Kuo, and S.-C. Shen, Ed., Elsevier, Amsterdam, Netherlands (2017) (ISBN-13: 978-0081019429).
Jae-Hyun Ryou, "Chapter 3. Gallium nitride (GaN) on sapphire substrates for visible LEDs," Nitride Semiconductor LEDs: Materials, Performance and Applications, J. J Huang, H.-C. Kuo, and S.-C. Shen, Ed., Woodhead Publishing, Cambridge, U.K. (2013) (ISBN-13: 978-0857095077).
Shyh-Chiang Shen, Jae-Hyun Ryou, and Russell D. Dupuis, "Chapter 13. GaN/InGaN heterojunction bipolar transistors using a direct-growth technology," Nano-Semiconductors: Devices and Technology, K. Iniewski, Ed., CRC Press, New York, New York, U.S.A. (2011) (ISBN-13: 978-1439848357).
Jae-Hyun Ryou, Ravi Kanjolila, and Russell D. Dupuis, "Chapter 6. CVD of III-V compound semiconductors," Chemical Vapour Deposition: Precursors, Processes, and Applications, A. Jones and M. L. Hitchman Ed., RSC (Royal Society of Chemistry) Publishing, Cambridge, U.K. (2009) (ISBN-13: 978-0854044658).
Jae-Hyun Ryou, Shyh-Chiang Shen, and Russell D. Dupuis, "Chapter 10. Ultraviolet photodetectors based on III-nitride semiconductors," Advanced Semiconductor Materials and Devices Research - SiC and III-Nitrides, H. Cha, Ed., Research Signpost, India (2009) (ISBN-13: 978-8178953717).

Dissertations Directed

Mina Moradnia, Ph.D. (May 2023), “Single-Crystalline III-N Film Growth for Photonic, Electronic, Sensing, and Energy Harvesting Applications,” Zetta Energy, Houston, TX
Miad Yarali, Ph.D. (Dec. 2022), “Ultra-Wide Bandgap AlN-Based Semiconductor Materials for Optoelectronic and Sensing Devices,” Samsung Austin Semiconductor, Austin, TX
Nam-In Kim, Ph.D. (Aug. 2022), “Flexible Piezoelectric Sensors Based on Single-Crystalline III-N Films for Personal Healthcare and Extreme-Environment Applications,” [Best Dissertation Award of Cullen College of Engineering and Materials Science and Engineering Program, 2022], University of Houston
Sara Pouladi, Ph.D. (May 2020), “High-Efficiency Flexible Thin-Film Single-Crystal-Like GaAs Solar Cells Based on Cheap Metal Tape,” [Best Dissertation Award of Materials Science and Engineering Program, Spring 2020], University of Houston
Weijie Wang, Ph.D. (Dec. 2019), “Strain Effect in III-N Thin Film Based High Electron Mobility Transistors,” [Best Dissertation Award of Department of Mechanical Engineering, Spring 2019], Lam Research, Fremont, CA
Jie Chen, Ph.D. (Aug. 2019), “Flexible Piezoelectric Generators and Pulse Sensors Using Single-Crystalline III-N Thin Films,” [Best Dissertation Award of Cullen College of Engineering and Materials Science and Engineering Program, Spring 2019], Applied Optoelectronics Inc., Sugar Land, TX
Shahab Shervin, Ph.D. (May 2017), “Flexible III-Nitride-Based Materials and Devices for Electronic and Photonic Applications. [Best Dissertation Award of Materials Science and Engineering Program, Spring 2017], ASML. Wilton, CT
Mojtaba Asadirad, Ph.D. (Aug. 2016), “High-Performance Flexible Thin-Film Electronics Based on Single-Crystal-Like Inorganic Semiconductor Materials,” [Best Dissertation of Materials Science and Engineering Program, Spring 2016], Micron Technology, Boise, ID

Patents

Jae-Hyun Ryou, Shahab Shervin, and Seung-Hwan Kim, “Externally-strain-engineered semiconductor photonic and electronic devices and assemblies and methods of making same,” US Patent 10897120 (Jan. 19, 2021).
Jae-Hyun Ryou, “Flexible single-crystalline semiconductor device fabrication and methods of thereof,” US Patent 10411035 (Sep. 10, 2019).
Jae-Hyun Ryou, Shahab Shervin, and Seung-Hwan Kim, “Externally-strain-engineered semiconductor photonic and electronic devices and assemblies and methods of making same,” US Patent 10476234 (Nov. 12, 2019).
Jae-Hyun Ryou, “Flexible single-crystalline semiconductor device fabrication and methods of thereof,” US Patent 9831273 (Nov. 27, 2017).
Daniel Guidotti, Gee-Kung Chang, Jae-Hyun Ryou, and Russell D. Dupuis, “Edge viewing photo detector and method of making same,” US Patent 7482667 (Jan. 27, 2009).
Tzu-Yu Wang, Hoki Kwon, Jae-Hyun Ryou, Gyoungwon Park, and Jin K. Kim “InP-based long wavelength VCSEL,” US Patent 7433381 (Oct. 7, 2008).
Tzu-Yu Wang, Jin K. Kim, Hoki Kwon, Gyoungwon Park, and Jae-Hyun Ryou, “Carrier bonded 1550nm VCSEL with InP substrate removal,” US Patent 7286584 (Oct. 23, 2007).
Jae-Hyun Ryou and Gyoungwon Park, “Dielectric VCSEL gain guide,” US Patent 7277461 (Oct. 2, 2007).
Jae-Hyun Ryou, “Pseudomorphic layer in tunnel junction,” US Patent 7136406 (Nov. 14, 2006).
Jae-Hyun Ryou, Michael D. Ringle, and Yue Liu, “VCSEL having thermal management,” US Patent 7075962 (Jul. 11, 2006).
Jae-Hyun Ryou, Tzu-Yu Wang, Jin K. Kim, Gyoungwon Park, and Hoki Kwon, “Enhanced lateral oxidation,” US Patent 7054345 (May 30, 2006).
Ying-Lan Chang, Scott W. Corzine, Russell D. Dupuis, Min Soo Noh, Jae-Hyun Ryou, Michael R. T. Tan, and Ashish Tandon, “Long-wavelength photonic devices with GaAsSb quantum-well layers,” US Patent 6711195 (Mar. 23, 2004).