Welcome to Tansu's Group at Lehigh University!

Our research laboratory is affiliated with the Center for Optical Technologies (COT) and Electrical and Computer Engineering, within in the  P. C. Rossin College of Engineering and Applied Science at Lehigh University (Bethlehem, PA. The city is ranked as one of the 100 best places to live and launch 2008 ). Our research work is to advance the science and technology of semiconductor optoelectronics, based on low-dimensional (or semiconductor nanostructure) gain media. The pursuit of our research covers both the theoretical and experimental aspects of the physics, devices, and MOCVD growth of semiconductor optoelectronics material and devices, compound semiconductors, and low-dimensional semiconductors. Our research field, which is in the Applied Physics area, utilizes knowledge and ideas derived from fundamental physics to advance the science & technology of semiconductor optoelectronics for engineering applications.

The experimental aspects include the material epitaxy with metalorganic chemical vapor deposition (MOCVD) & device fabrications of III-V and III-Nitride compound semiconductor nanostructures and optoelectronics devices. In our laboratory (as part of Center for Optical Technologies), we currently have two MOCVD reactors, with one reactor dedicated for the III-Nitride (GaN-based) optoelectronics and nanostructures research (P-75 reactor) and the other for GaAs / InP-based optoelectronics and nanostructures research (D-125 reactor).

Several focus of our research works are listed below. Our research works on semiconductor nanostructure and optoelectronics primarily focus on applications in the fields of energy (wide bandgap semiconductor for high-efficiency solid state lightings, and high-efficiency solar photovoltaic cells), optical communications (dilute-nitride or InGaAsN QW lasers), free space and NLOS communications (mid-IR lasers and UV LEDs), biological and chemical sensors (mid-IR and UV optoelectronics), and recently also on III-Nitride based dilute-magnetic semiconductors and surface plasmonics.

We are also very enthusiastic to develop new collaborations with partners from academia, industries, and national laboratories. Thanks!

Selected Recent News / Publications / Patents:                                                  (for full list, please refer to Publication or CV)

·         R. A. Arif, Y. K. Ee, and N. Tansu, “Enhancement of Radiative Efficiency of Nitride-Based LEDs via Staggered InGaN Quantum Wells Emitting at 420-500 nm,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2007, Baltimore, MD, May 2007. (pdf)

·         Y. K. Ee, P. Kumnorkaew, R. A. Arif, J. F. Gilchrist, and N. Tansu, “Enhancement of Light Extraction Efficiency of InGaN Quantum Wells LEDs Using SiO₂ Microspheres,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2007, Baltimore, MD, May 2007. (pdf)

·         Y. K. Ee, R. A. Arif, M. Jamil, and N. Tansu, “MOCVD Epitaxy and Optical Properties of Self-Assembled InGaN Quantum Dots via Stranski-Kastranow Growth Mode Emitting at 520-nm,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2007, Baltimore, MD, May 2007.(pdf)

·          (Invited Conference Paper) R. A. Arif, Y. K. Ee, H. Zhao, M. Jamil, and N. Tansu, “Nanostructure Engineering of InGaN-Based Active Regions for Improved III-Nitride Gain Media Emitting at 420-650 nm,” in Proc. of the European MRS (E-MRS) Spring Meeting 2007: Symposium F: Novel Gain Materials and Devices Based on III-N-V Compounds, Strasbourg, France, May-June 2007.

·          M. Jamil, R. A. Arif, Y. K. Ee, H. Tong, J. B. Higgins, and N. Tansu, “MOCVD Epitaxy of InN Films on GaN Templates Grown on Sapphire and Silicon (111) Substrates,” in Proc. of the 13^th Biennial Workshop on Organometallic Vapor Phase Epitaxy (OMVPE) 2007, Salt Lake City, UT, August 2007.

·          Y. K. Ee, H. Zhao, R. A. Arif, M. Jamil, and N. Tansu, “Self-Assembled InGaN Quantum Dots on GaN Grown by Metalorganic Vapor Phase Epitaxy ,” in Proc. of the 13^th Biennial Workshop on Organometallic Vapor Phase Epitaxy (OMVPE) 2007, Salt Lake City, UT, August 2007.

·          R. A. Arif, Y. K. Ee, and N. Tansu, “Polarization Engineering via Staggered InGaN Quantum Wells for Radiative Efficiency Enhancement of Light Emitting Diodes Emitting,” Appl. Phys. Lett., vol. 91 (9), Art. 091110, August 2007. (pdf)

·          H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical Gain Analysis of Strain Compensated InGaN-AlGaN Quantum Well Active Regions for Lasers Emitting at 420-520 nm,” in Proc. of the 7^th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2007), Newark, DE, September 2007. (pdf)

·          E. Readinger, G. Chern, H. Shen, M. Wraback, R. A. Arif, Y. K. Ee, and N. Tansu, "Optical and Physical Properties of In-faced InN/InGaN Multi-Quantum Wells Grown on GaN Templates by Plasma-Assisted Molecular Beam Epitaxy," in Proc. of the North America Molecular Beam Epitaxy (NAMBE) Conference 2007, Alburqueque, NM, September 2007. (pdf)

·          Y. K. Ee, R. A. Arif, N. Tansu, H. Li, H. M. Chan, R. P. Vinci, P. Capek, N. K. Jha, and V. Dierolf, “Improved Photoluminescence of InGaN Quantum Wells Grown on Nano-Patterned AGOG Sapphire Substrate by Metalorganic Vapor Phase Epitaxy,” in Proc. of the 20^th IEEE Laser and Electro-Optics Society (LEOS) Annual Meeting 2007, Lake Buena Vista, FL, October 2007. (pdf)

·          H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical Gain Analysis of Staggered InGaN Quantum Wells Active Regions for Lasers Emitting at 420-500 nm,” in Proc. of the 20^th IEEE Laser and Electro-Optics Society (LEOS) Annual Meeting 2007, Lake Buena Vista, FL, October 2007. (pdf)

·          G. Tsvid, J. Kirch, L. J. Mawst, M. Kanskar, J. Cai, R. A. Arif, N. Tansu, P. M. Smowton, and P. Blood, “Radiative Efficiency of InGaAs / InGaAsP / GaAs Quantum Well Lasers,” in Proc. of the 20^th IEEE Laser and Electro-Optics Society (LEOS) Annual Meeting 2007, Lake Buena Vista, FL, October 2007. (pdf)

·          Y. K. Ee, P. Kumnorkaew, R. A. Arif, J. F. Gilchrist, and N. Tansu, “Enhancement of Light Extraction Efficiency of InGaN Quantum Wells Light Emitting Diodes Using SiO₂ / Polystyrene Microlens Arrays,” Appl. Phys. Lett., vol. 91 (22), Art. 221107, November 2007. (pdf)

·          H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical Gain Analysis of Strain-Compensated InGaN–AlGaN Quantum Well Active Regions for Lasers Emitting at 420-500 nm,” Optical and Quantum Electronics, vol.39(14-15), December 2007. (pdf)

·        (Invited Journal Paper) R. A. Arif, Y. K. Ee, and N. Tansu, “Nanostructure Engineering of InGaN-Based Active Regions for Improved III-Nitride Gain Media Emitting at 420-550 nm,” in Physica Stat. Solidi (c), vol. 205 (1), pp. 96-100, January 2008. (pdf)

·       R. A. Arif, H. Zhao, and N. Tansu, “Type-II InGaN-GaNAs Quantum Wells Active Regions for Lasers Applications,” Appl. Phys. Lett. vol. 92(1), Art. No. 011104, January 2008. (pdf)

·          R. A. Arif, Y. K. Ee, H. Zhao, and N. Tansu, “Radiative Efficiency and Spontaneous Recombination Rate of Staggered InGaN Quantum Wells Light Emitting Diodes Emitting at 420-510 nm,” in Proc. of the SPIE Photonics West 2007, Light-Emitting Diodes: Research, Manufacturing, and Applications XII, San Jose, CA, Jan 2008.

·          Y. K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, J. F. Gilchrist, and N. Tansu, “Comparison of Numerical Modeling and Experiments of InGaN Quantum Wells Light Emitting Diodes with SiO₂ / Polystyrene Microlens Arrays,” in Proc. of the SPIE Photonics West 2007, Light-Emitting Diodes: Research, Manufacturing, and Applications XII, San Jose, CA, Jan 2008.

·          H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Optical Gain and Spontaneous Emission of Strain-Compensated InGaN-AlGaN Quantum Wells Including Carrier Screening Effect,” in Proc. of the SPIE Photonics West 2007, Physics and Simulation of Optoelectronics Devices XVI, San Jose, CA, Jan 2008.

·        Y. K. Ee, H. Zhao, R. A. Arif, M. Jamil, and N. Tansu, “Self-Assembled InGaN Quantum Dots on GaN Emitting at 520 nm Grown by Metalorganic Vapor Phase Epitaxy ,” J. Crystal Growth, vol. 310(7-9), pp.2320-2325, April 2008. (pdf)

·         C. C. Hsu, J. H. Lin, Y. H. Lin, H. C. Kuo, S. C. Wang, W. F. Hsieh, N. Tansu, and L. J. Mawst, “Ultrafast Carrier Dynamics of InGaAsN and InGaAs Single Quantum Wells,” J. Phys. D: Appl. Phys., vol. 41(8), Art. 085107, April 2008. (pdf)

·       H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Approaches for Low-Threshold ‘Green’ Nitride Lasers Diodes,” in IEEE Semiconductor Lasers Workshop 2008, San Jose, CA, May 2008.

·         R. A. Arif, H. Zhao, and N. Tansu, “InGaN-GaNAs Type-II ’W’ Quantum Well Lasers for Emission at 450-nm,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2008, San Jose, CA, May 2008. (pdf)

·         H. Zhao, R. A. Arif, G. S. Huang, Y. K. Ee, and N. Tansu, “Self-Consistent Optical Gain Analysis and Epitaxy of Strain-Compensated InGaN-AlGaN Quantum Wells for Laser Applications,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2008, San Jose, CA, May 2008. (pdf)

·         R. A. Arif, H. Zhao, Y. K. Ee, S. T. Penn, V. Dierolf, and N. Tansu, “Spontaneous Recombination Rate and Luminescence Efficiency of Staggered InGaN Quantum Wells Light Emitting Diodes,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2008, San Jose, CA, May 2008. (pdf)

·         Y. K. Ee, P. Kumnorkaew, R. A. Arif, H. Tong, J. F. Gilchrist, and N. Tansu, “Size Effects and Light Extraction Efficiency Optimization of III-Nitride Light Emitting Diodes with SiO₂ / Polystyrene Microlens Arrays,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2008, San Jose, CA, May 2008. (pdf)

·         S. K. Tripathy, G. Xu, X. Mu, Y. J. Ding, M. Jamil, R. A. Arif, and N. Tansu, “Resonant Raman Scattering of Coherent Picosecond Pulses by One and Two Longitudinal-Optical Phonons in GaN Film Grown on Silicon (111) Substrate,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2008, San Jose, CA, May 2008. (pdf)

·         X. Mu, Y. J. Ding, R. A. Arif, M. Jamil, and N. Tansu, “Observation of Enhanced THz Emission from InGaN/GaN Multiple Quantum Wells,” in Proc. of the IEEE/OSA Conference on Lasers and Electro-Optics (CLEO) 2008, San Jose, CA, May 2008. (pdf)

·       R. A. Arif, H. Zhao, Y. K. Ee, and N. Tansu, “Spontaneous Emission and Characteristics of Staggered InGaN Quantum Wells Light Emitting Diodes,” IEEE J. Quantum Electron., vol. 44(6), pp.573-580, June 2008. (pdf)

·       M. Jamil, H. Zhao, J. Higgins, and N. Tansu, “Narrow Band Gap (0.77 eV) InN on GaN / Sapphire Substrate by Pulsed MOCVD Growth Mode,” in Proc. of the TMS Electronics Material Conference (EMC) 2008, Santa Barbara, CA, June 2008. (accepted).

·       M. Jamil, H. Zhao, J. Higgins, and N. Tansu, “MOVPE Growth and Photoluminescence of Narrow-Bandgap InN Alloys on GaN / Sapphire Substrate Using Pulsed Growth Mode,” in Proc. of the 14^th Int. Conf. – Metalorganic Vapor Phase Epitaxy (IC-MOVPE XIV) 2008, Metz, France, June 2008 (accepted).

·       (Invited Conference Paper) N. Tansu, R. A. Arif, Y. K. Ee, H. Zhao, H. Tong, M. Jamil, and G. S. Huang, “Nano-Engineering of III-Nitride Semiconductor Optoelectronics and New Applications,” in Proc. of the International Conferences of Materials and Technologies (CIMTEC) 2008 – 3rd International Conference on Smart Materials, Structures and Systems, Sicily, Italy, June 2008 (accepted).

·         M. Jamil, R. A. Arif, Y. K. Ee, H. Tong, J. B. Higgins, and N. Tansu, “MOVPE of InN films on GaN Templates grown on sapphire and silicon (111) Substrates,” in Physica Stat. Solidi (a) vol. 205 (7), pp.1619-1624, July 2008. (pdf)

·         (Invited Journal Paper) L. J. Mawst, J. Y. T. Huang, D. P. Xu, J. Y. Yeh, and G. Tsvid, T. F. Kuech, and N. Tansu, “MOCVD grown Dilute-Nitride Type-II Quantum Wells,” in IEEE Selected Topics in J. Quantum Electron., vol. 14(4), pp. 979-991, July / August 2008. (pdf)

·       (Invited Conference Paper) N. Tansu, R. A. Arif, H. Zhao, and Y. K. Ee, “Polarization Engineering of III-Nitride Nanostructures for High-Efficiency Light Emitting Diodes,” in Proc. of the SPIE Optics + Photonics 2008, The 8^th International Conference on Solid State Lighting, San Diego, CA, August 2008.

·         G. Tsvid, J. Kirch, L. J. Mawst, M. Kanskar, J. Cai, R. A. Arif, N. Tansu, P. M. Smowton, and P. Blood, “Spontaneous Radiative Efficiency and Gain Characteristics of Strained Layer InGaAs / GaAs Quantum Well Laser,” in IEEE J. Quantum Electron. , vol. 44(8), pp. 732-739, August 2008 (pdf).

·         P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Rapid Convective Deposition Of Microsphere Monolayers for Fabrication Of Microlens Arrays,” in Proc. of the 15^th International Congress on Rheology 2008, The Society of Rheology 80th Annual Meeting, Monterey, CA, August 2008 (accepted).

·       H. Zhao, R. A. Arif, and N. Tansu, “Self Consistent Analysis of Type-II 'W' InGaN-GaNAs Quantum Well Lasers,” J. Appl. Phys., vol. 104(5), 043104, September 2008 (pdf).

·       H. Zhao, R. A. Arif, Y. K. Ee, and N. Tansu, “Self-Consistent Analysis of Strain-Compensated InGaN-AlGaN Quantum Wells for Lasers and Light Emitting Diodes,” IEEE J. Quantum Electron., vol. 44(10), October 2008. (pdf)

·         M. Jamil, H. Zhao, J. Higgins, and N. Tansu, “MOVPE and Photoluminescence of Narrow Band Gap (0.77 eV) InN on GaN / Sapphire by Pulsed Growth Mode,” in Physica Stat. Solidi (a) (accepted)

·         M. Jamil, H. Zhao, J. Higgins, and N. Tansu, “Influence of Growth Temperature and V/III Ratio on the Optical characteristics of Narrow-Band Gap (0.77 eV) InN Grown on GaN / Sapphire Using Pulsed MOVPE,” in J. Crys. Growth (accepted).

·         (Cover Article) P. Kumnorkaew, Y. K. Ee, N. Tansu, and J. F. Gilchrist, “Deposition of Microsphere Monolayers for Fabrication of Microlens Arrays,” Langmuir, vol. 24 (21), November 2008. (pdf).

 

·          Luke J. Mawst, Nelson Tansu, Igor Vurgaftmann, and Jerry R. Meyer, “Type-II Quantum Well Mid-Infrared Optoelectronic Devices“ Novel techniques to achieve 3000-5000 nm wavelength emission. Lasers, US Patent No. 7,256,417; approved on August 14^th 2007.

·          Luke J. Mawst, Nelson Tansu, and Jeng-Ya Yeh, Novel techniques on dilute-nitride semiconductor for long wavelength lasers on GaAs.  (US-Patent filed, pending).

·          Nelson Tansu, Ronald A. Arif, and Yik Khoon Ee, Novel techniques to achieve high performance visible LEDs and lasers. (US-Patent filed, pending).

·          Nelson Tansu, Ronald A. Arif, and Yik Khoon Ee, Novel methods for achieving nitride-based gain media with significant enhancement in radiative recombination rate and optical gain for high efficiency LEDs and lasers.  (US-Patent filed, pending).

·          Nelson Tansu, Yik Khoon Ee, James F. Gilchrist, Pisist Kumnorkaew, and Ronald A. Arif, Novel techniques to achieve large light extraction efficiency of nitride-based LEDs using a low cost and straight forward approach.  (US-Patent filed, pending).

 

Contact Information:

Prof. Nelson Tansu, Ph.D.

The Peter C. Rossin Assistant Professor

Center for Optical Technologies

Dept of Electrical and Computer Engineering
Lehigh University
7 Asa Drive, Bethlehem, PA 18015, USA
Email: Tansu@Lehigh.Edu
Phone: (610) 758-2678 or (610) 75-TANSU