Nigel Shepherd

Associate Professor
Discovery Park E118
940-369-7714
Nigel.Shepherd@unt.edu
  • Research

    Optoelectronics and Thin Films Laboratory - Research          

    Our main focus is the growth of compound semiconductor thin films, and understanding their optical and carrier transport properties with the aim of engineering better power and external quantum efficiencies in solid state lighting and solar cell applications, along with higher switching speeds and lower power consumption for transistor applications.

    We routinely use photoluminescence, photoluminescence excitation, electroluminescence, excited state lifetime, power efficiency, quantum efficiency, current-voltage, capacitance-voltage, residual potential and temperature dependent Hall measurements to study the electro-optical properties of our materials (III-Vs, ZnS, ZnO, ITO, Al2O3, BaTa2O6, SiC, graphene, organics) and devices (alternating current thin film electroluminescence, inorganic light emitting diodes, solar cells, organic light emitting diodes and thin film transistors).

    • Vacuum deposition of compound semiconductor thin films
    • Processing-structure-properties relationships of electronic and optical materials
    • Optical and carrier transport properties
    • Electroluminescent devices, photovoltaics  and thin film batteries
  • Publications
    • Reinaldo Santos-Ortiz, Vyacheslav Volkov, Stefan Schmid, Fang-Ling Kuo, Kim Kisslinger, Soumya Nag, Rajarshi Banerjee, Feng Wang, Yimei Zhu and Nigel D. Shepherd, "The Microstructure and Electronic Band Structure of Pulsed Laser Deposited Iron Fluoride Thin-Film for Battery Electrodes", ACS Applied Materials and Interfaces, http://dx.doi.org/10.1021/am3017569, 2013.
    • Fang-Ling Kuo, Yun Li, Marvin Solomon, Jincheng Du and Nigel D Shepherd, "Workfunction tuning of zinc oxide films by argon sputtering and oxygen plasma: an experimental and computational study", Journal of Physics D: Applied Physics 45, p.065301, 2012.
    • Pradeep Gali, Fang-Ling Kuo, Nigel Shepherd and U Philipose, "Role of oxygen vacancies in visible emission and transport properties of indium oxide nanowires", Semiconductor Science and Technology 27, p.015015, 2012.
    • Minghang Li, Ming-Te Lin, Joyce Chen, Roy McDougald Jr, Ravi Arvapally, Mohammad Omary and Nigel D. Shepherd, "High efficiency orange-red phosphorescent organic light emitting diodes based on a Pt(II)-pyridyltriazolate complex from a structure optimized for charge balance and reduced efficiency roll-off",Physica Status Solidi A 209, No. 1, pg.221–225, 2012.
    • Fang-Ling Kuo, Mohammad H. Maneshian and Nigel D. Shepherd, "Electrical and chemical analysis of zinc oxide interfaces with high dielectric constant barium tantalate and aluminum oxide in metal-insulator-semiconductor structures fabricated at low temperatures", Thin Solid Films 520, Issue 1, pg. 475, 2011.
    • Minghang Li, Wei-Hsuan Chen, Ming-Te Lin, Iain Oswald, Mohammad Omary and Nigel D. Shepherd, "High Efficiency Electrophosphorescence from Bilayer Organic Light Emitting Diodes", Journal of Physics: D Applied Physics 44, pg. 365103, 2011.
    • M. H. Maneshian, F. L. Kuo, K. C. Mahdak, J. Y. Hwang, R. Banerjee, and Nigel. D. Shepherd, "The influence of high dielectric constant aluminum oxide sputter deposition on the structure and properties of multilayer epitaxial graphene", Nanotechnology 22, pg.205703 (7pg), 2011.
    • Evan Law, Mark Davidson, Nigel Shepherd and Paul H. Holloway, "Enhanced outcoupling of electroluminescence from ZnS:ErF3 thin films by a photonic crystal", Journal of Vacuum Science and Technology B, 29, pg. 011003 (7pgs), 2011.  
    • M. H. Maneshian, K. C. Mahdak, F.L. Kuo, J.Y. Hwang, R. Banerjee and N. D. Shepherd, "Atomic scale characterization of titanium Ohmic contacts to SiC using three dimensional atom probe tomography and high resolution transmission electron microscopy",  Applied Physics Letters 97,  pg.024103(3pg), 2010.
    • Fang Ling Kuo, Ming-Te Lin, Benedict A. Mensah, Thomas W. Scharf and Nigel D. Shepherd, "A comparative study of the photoluminescence and conduction mechanisms of low temperature pulsed laser deposited and atomic layer deposited zinc oxide thin films",  Physica Status Solidi A 207 (No 11), pg.2487-2491, 2010.
    • Mohammad H. Maneshian, Ming-Te Lin, David Diercks, and Nigel D. Shepherd, "Structural and electrical characterization of Ohmic contacts to graphitized silicon carbide", Nanotechnology 20, 495703 (7pg), 2009.
    • Minghang Li, Wei-Hsuan Chen, Ming-Te Lin, Mohammad A. Omary, and Nigel D. Shepherd, "Near-white and tunable electrophosphorescence from bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) based organic light emitting diodes", Organic Electronics 20, pg.863-870, 2009.
    • William Glass, Ajay Kale, Nigel Shepherd, Mark Davidson, David DeVito and Paul H. Holloway, "Sputter Deposited Electroluminescent Zinc Sulfide Thin Films Doped with Rare Earths", Journal of Vacuum Science and Technology A, Volume 25 (3), pg. 492-499, 2007.
    • Nigel Shepherd, David C. Morton, Eric W. Forsythe and Dave Chiu, "The influence of insulator properties on the electro-optical performance of flexible ZnS:ErF3 alternating current thin film electroluminescent devices",  Thin Solid Films, Volume 515, Issue 4, pg. 2342-2346, 2006.
    • Kenneth Dedeian, Jianmin Shi, Nigel Shepherd, Eric Forsythe, and David C. Morton, "Photophysical and  Electrochemical Properties of Heteroleptic Tris-Cyclometalated Iridium(III) Complexes" , Inorganic  Chemistry,  44, pg. 4445-4447, 2005. 
    • Nigel Shepherd and Paul H. Holloway, "Zinc Sulfide",  in Handbook of Electroluminescent Materials,    Chapter 2, pages 27-117, Ed. D.R. Vij, Institute of Physics Publishing,  London, 2004.
    • J.H. Kim, N. Shepherd, M. Davidson and P. Holloway, "Sputter deposited GaN doped Erbium Thin Films: Photoluminescence and Infra-red Electroluminescence", Applied Physics Letters, Volume 83, No 4, pg. 641-643, 2003.
    • J.H. Kim, N. Shepherd, M. Davidson and P.  Holloway, "Visible and Near-Infrared Alternating Current Electroluminescence from Sputter   Grown GaN Thin Film Doped with Er", Applied Physics Letters, Volume 83, No 21, pg. 4279-4281, 2003.
    • Kale, N.   Shepherd, W. Glass, D. DeVito, M. Davidson and Paul H. Holloway, "Infrared Emission from Zinc-Sulfide: Rare-Earth Doped Thin Films", Journal of Applied Physics, Volume 94, No 5, pg. 3147-3152, 2003.
    • R.E. Hummel, N. Shepherd and D. Burton, "Interpretation of Photoluminescence Spectra Obtained for Spark-Processed Silicon", Applied Physics Letters, Volume 79, No 20, pg. 3218-3220, 2001.
  • Groups