welcome





Education:
1991-1996: PhD, Physics, University of British Columbia
1987-1991: BSc (Honors) 1st Class, Physics, Simon Fraser University

Academic Experience:
2006-present: Senior Research Scientist (continuing/tenured), Arizona State University
2001-2006: Associate Research Scientist (continuing/tenured), Arizona State University
1996-2001: Assistant Research Scientist (probationary track), Arizona State University
1991-1996: Graduate Research & Teaching Assistant, University of British Columbia
1988-1991: Research Assistant, Simon Fraser University

Industrial Experience:
2006-present: Consultant (optical engineering), Synergistic Detector, Fountain Hills, AZ
2004-present: Consultant (III-V laser growth & design), Trion Technology, Tempe, AZ
2000-2006: Consultant (VCSELs & THz lasers), Lytek Corporation, Phoenix, AZ
2000-2001: Consultant (midwave IR lasers & detectors), Optolocity, Scottsdale, AZ
1997-1998: Consultant (band edge thermometry), Tokyo Electron Labs, Tempe, AZ
1993-1994: Consultant (optical thermometry), Thermionics, Port Townsend, WA

Honors and Awards:
2003-2004: Outstanding technical contributions in the areas of optoelectronics and molecular beam epitaxy and outstanding service, Waves and Devices Chapter, Phoenix Section, Institute of Electrical and Electronics Engineers
1996-1998: Natural Science and Engineering Research Council of Canada Postdoctoral Fellowship
1993-1996: Science Council of British Columbia Graduate Research, Engineering, and Technology Award
1991-1995: Natural Science and Engineering Research Council of Canada Postgraduate Scholarship
1991-1996: Graduate Fellowship, University of British Columbia
1988-1989: Honor Roll, Simon Fraser University

Areas of Research
• Thermodynamics of energy conversion devices
• Optical properties & thermodynamics of semiconductor optical refrigeration devices
• Surfactant mediated epitaxy & isoelectronic co-doping of III-V semiconductor materials
• Novel current profiling in oxide confined vertical-cavity surface-emitting lasers (VCSELs)
• Longwave IR & THz quantum cascade lasers for sensing & imaging applications
• GaAsSb/GaAs based 1.3 µm datacom VCSELs
• Optical and electronic properties of antimonide based III-V semiconductors
• Novel mixed group-V materials for longwave lasers & detectors on GaAs substrates
• Molecular beam epitaxy (MBE) growth of III-V materials & optoelectronic devices
• Noncontact thermometry using diffuse reflectance spectroscopy (DRS)
• Closed-loop control of epitaxial growth using spectroscopic ellipsometry and DRS

Areas of Teaching
• Optoelectronic device design & simulation
• Semiconductor material properties & applications in optoelectronic devices
• Epitaxial growth of III-V compound semiconductor materials & devices
• Process control & in-situ characterization of epitaxial growth
• Design, operation, & maintenance of ultra-high vacuum solid-source MBE systems

Professional Service
Scientific and Professional Societies
2006-present: Senior Member, Institute of Electrical and Electronics Engineers
2000-2006: Member, Institute of Electrical and Electronics Engineers (IEEE)
2001-present: Member, IEEE Lasers and Electro-Optics Society (LEOS)
2001-present: Member, SPIE-The International Society for Optical Engineering
1993-present: Member, American Physical Society

Conference and Workshop Activity
2005-2006: Program Committee, Organizing Committee, and Session Chair, 33rd International Symposium on Compound Semiconductors (ISCS-2006)
2002-2006: Arrangements Committee Chair, 1st, 2nd, 3rd, 4th, & 5th IEEE Phoenix Section Workshop on Devices and Packaging for Communication and Computing
2001-2005: Program Committee Member and Session Chair, 20th, 21st, 22nd, & 23rd North American Conference on Molecular Beam Epitaxy
1999-2000: Organizing Committee Chair, 19th North American Conference on Molecular Beam Epitaxy (hosted by Arizona State University)

Professional Committee Activity
2002-present: LEOS Representative, Waves and Devices Chapter, Phoenix Section, IEEE
2001-2002: Publicity Chair, Waves and Devices Chapter, Phoenix Section, IEEE
2000-2001: LEOS Representative, Waves and Devices Chapter, Phoenix Section, IEEE

Journal Referee
• Applied Physics Letters
• Electrochemical and Solid-State Letters
• Electrochemical Society Letters
• Journal of Applied Physics
• Journal of Crystal Growth
• Journal of Electronic Materials
• Journal of Vacuum Science and Technology
• Material Science and Engineering
• Materials Research Bulletin
• Optical Engineering

Publication Summary
• 63 referred journal papers
• 97 conference proceedings papers and abstracts
• 22 invited & 118 contributed presentations
• 10 patents

Selected Publications
Referred Journals
• J.-B. Wang, D. Ding, S. R. Johnson, S.-Q. Yu, Y.-H. Zhang, Determination and improvement of spontaneous emission quantum efficiency in GaAs/AlGaAs heterostructures grown by molecular beam epitaxy, Phys. Stat. Sol. (a) (submitted Nov, 2006).
• S. R. Johnson, D. Ding, J.-B. Wang, S.-Q. Yu, Y.-H. Zhang, Excitation Dependent Photoluminescence Measurements of the Nonradiative Lifetime and Quantum Efficiency in GaAs, J. Vac. Sci. Technol. B (submitted Oct, 2006).
• C. Bückers, G. Blume, A. Thränhardt, C. Schlichenmaier, P. J. Klar, G. Weiser, S. W. Koch, J. Hader, J. V. Moloney, T. J. C. Hosea, S. J. Sweeney, S. R. Johnson, Y.-H. Zhang, Microscopic Electroabsorption Lineshape Analysis for Ga(AsSb)/GaAs Heterostructures, J. Appl. Phys. (submitted Aug, 2006).
• D. Ding, S. R. Johnson, J.-B. Wang, S.-Q. Yu, Y.-H. Zhang, Intrinsic Irreversibility in Semiconductor Light Emission, Phys. Stat. Sol. (c) (accepted Sept, 2006).
• K. Hild, S. J. Sweeney, S. Wright, D. A. Lock, S. R. Jin, I. P. Marko, S. R. Johnson, S. A. Chaparro, S.-Q. Yu, Y.-H. Zhang, Carrier recombination in 1.3 µm GaAsSb/GaAs Quantum Well Lasers, Appl. Phys. Lett. 89, 173509 (2006).
• L. Borkovska, O. Yefanov, O. Gudymenko, S. R. Johnson, V. Kladko, N. Korsunska, T. Kryshtab, Yu. G. Sadofyev, Y.-H. Zhang, Effect of Growth Temperature on the Luminescent and Structural Properties of InGaAsSbN/GaAs Quantum Wells for 1.3 μm Telecom Applications, Thin Solid Films 515, 786 (2006).
• N. A. Kabir, Y. Yoon, J. R. Knab, J.-Y. Chen, A. G. Markelz, J. L. Reno, Yu. G. Sadofyev, S. R. Johnson, Y.-H. Zhang, J. P. Bird, Terahertz Transmission Characteristics of High-Mobility GaAs and InAs Two-Dimensional-Electron-Gas Systems, Appl. Phys. Lett. 89, 132109 (2006).
• J.-B. Wang, S. R. Johnson, D. Ding, S.-Q. Yu, Y.-H. Zhang, Influence of photon recycling on semiconductor luminescence refrigeration, J. Appl. Phys. 100, 043502 (2006).
• S.-Q. Yu, X. Jin, S. R. Johnson, Y.-H. Zhang, Gain Saturation and Carrier Distribution Effects in Molecular Beam Epitaxy Grown GaAsSb/GaAs Quantum Well Lasers, J. Vac. Sci. Technol. B 24, 1617 (2005).
• N. Samal, S. R. Johnson, D. Ding, A. K. Samal, S.-Q. Yu, Y.-H. Zhang, High-Power Single-Mode Vertical-Cavity Surface-Emitting Lasers, Appl. Phys. Lett. 87, 161108 (2005).
• Yu. G. Sadofyev, A. Ramamoorthy, J. P. Bird, S. R. Johnson, Y.-H. Zhang, Large Negative Persistent Photoconductivity in InAs/AlSb Quantum Wells, Appl. Phys. Lett. 86, 192109 (2005).
• Yu. G. Sadofyev, A. Ramamoorthy, J. P. Bird, S. R. Johnson, Y.-H. Zhang, Infrared Light Induced Beating of Shubnikov-de Haas Oscillations in MBE grown InAs/AlSb Quantum Wells, J. Crystal Growth 278, 661 (2005).
• J.-B. Wang, S. R. Johnson, S. A. Chaparro, D. Ding, Y. Cao, Yu. G. Sadofyev, Y.-H. Zhang, Band Edge Alignment of Pseudomorphic GaAs1-ySby on GaAs, Phys. Rev. B 70, 195339 (2004).
• S. R. Johnson, Yu. G. Sadofyev, D. Ding, Y. Cao, S. A. Chaparro, K. Franzreb, Y.-H. Zhang, Sb-Mediated Growth of n and p Type AlGaAs by Molecular Beam Epitaxy, J. Vac. Sci. Technol. B 22, 1436 (2004).
• P. Dowd, S. R. Johnson, S. A. Feld, M. Adamcyk, S. A. Chaparro, J. Joseph, K. Hilgers, M. P. Horning, K. Shiralagi, Y.-H. Zhang, Long Wavelength GaAsP/GaAs/GaAsSb VCSELs on GaAs Substrates for Communications Applications, Electron. Lett. 39, 987 (2003).
• S. R. Johnson, C.-Z. Guo, S. A. Chaparro, Yu. G. Sadofyev, J.-B. Wang, Y. Cao, N. Samal, X. Jin, S.-Q. Yu, D. Ding, Y.-H. Zhang, GaAsSb/GaAs Band Alignment Evaluation for Long-Wave Photonic Applications, J. Crystal Growth 251, 521 (2003).
• Yu. G. Sadofyev, A. Ramamoorthy, B. Naser, J. P. Bird, S. R. Johnson, Y.-H. Zhang, Large g-Factor Enhancement in High-Mobility InAs/AlSb Quantum Wells, Appl. Phys. Lett. 81, 1833 (2002).
• R. Leon, J. Ibanez, S. Marcinkevicius, J. Siegert, T. Paskova, B. Monemar, S. Chaparro, C. Navarro, S. R. Johnson, Y.-H. Zhang, Defect States in Red-Emitting InxAl1-xAs Quantum Dots, Phys. Rev. B 66, 085331 (2002).
• M. Canonico, C. Poweleit, J. Menéndez, A. Debernardi, S. R. Johnson, Y.-H. Zhang, Anomalous LO Phonon Lifetime in AlAs, Phys. Rev. Lett. 88, 215502 (2002).
• S. R. Johnson, S. Chaparro, J.-B. Wang, N. Samal, Y. Cao, Z.-B. Chen, C. Navarro, X. Jin, S.-Q. Yu, D. J. Smith, C.-Z. Guo, P. Dowd, W. Braun, Y.-H. Zhang, GaAs-Substrate Based Long-Wave Active Materials with Type-II Band Alignments, J. Vac. Sci. Technol. B 19, 1501 (2001).
• J. Ibanez, R. Leon, D. T. Vu, S. Chaparro, S. R. Johnson, C. Navarro, Y.-H. Zhang, Tunneling Carrier Escape from InAs Self-Assembled Quantum Dots, Appl. Phys. Lett. 79, 2013 (2001).
• V. Pacradouni, W. J. Mandeville, A. R. Cowan, P. Paddon, J. F. Young, S. R. Johnson, Photonic Band Structure of Dielectric Membranes Periodically Textured in Two Dimensions, Phys. Rev. B 62, 4204 (2000).
• W. Braun, P. Dowd, C.-Z. Guo, S. L. Chen, C. M. Ryu, U. Koelle, S. R. Johnson, Y.-H. Zhang, J. W. Tomm, T. Elsasser, D. J. Smith, Strained InGaAs/GaPAsSb Heterostructures Grown on GaAs (001) for Optoelectronic Applications in the 1100 nm – 1550 nm Range, J. Appl. Phys. 88, 3004 (2000).
• S. R. Johnson, P. Dowd, W. Braun, U. Koelle, C. M. Ryu, M. Beaudoin, C.-Z. Guo, Y.-H. Zhang, Long Wavelength Pseudomorphic InGaPAsSb Type-I and Type-II Active Layers Grown on GaAs, J. Vac. Sci. Technol. B 18, 1545 (2000).
• M. Beaudoin, E. Grassi, S. R. Johnson, K. Ramaswamy, K. Tsakalis, T. L. Alford, Y.-H. Zhang, Real-Time Composition Control of InAlAs Near lattice Matched to InP Using Spectroscopic Ellipsometry, J. Vac. Sci. Technol. B 18, 1435 (2000).

Invited talks
• S. R. Johnson, Y.-H. Zhang, MBE Growth of Compound Semiconductor Materials, Summer School on Semiconductor Nanostructures and Optoelectronic Devices, International Institute of Advanced Studies, Beijing, China, August 2005.
• S. R. Johnson, P. Dowd, S. A. Chaparro, S. A. Feld, M. Adamcyk, N. Samal, X. Jin, M. P. Horning, J.-B. Wang, S. Q. Yu, D. Ding, Y. Cao, Yu. G. Sadofyev, Y.-H. Zhang, Long Wavelength 1.3 µm GaAsSb/GaAs VCSELs on GaAs Substrates, 21st North American Conference on Molecular Beam Epitaxy: Workshop, Keystone CO, September 2003.
• M. Adamcyk, S. A. Chaparro, P. Dowd, S. A. Feld, K. Hilgers, S. R. Johnson, J. Joseph, B. Liang, K. Shiralagi, S.-Q. Yu, Y.-H. Zhang, 1.3 µm GaAsSb/GaAs VCSELs for Telecommunications Applications, SPIE Photonics West, San Jose CA, January 2003.
• S. R. Johnson, Y.-H. Zhang, C.-Z. Guo, S. A. Chaparro, Yu. G. Sadofyev, Y. Cao, D. Ding, J.-B. Wang, N. Samal, P. Dowd, C. Navarro, J. Xu, S.-Q. Yu, D. J. Smith, GaAsP/GaAs/GaAsSb Long Wavelength VCSELs Grown by MBE, Fourteenth American Conference on Crystal Growth & Epitaxy, Seattle WA, August 2002.
• S. R. Johnson, C.-Z. Guo, S. A. Chaparro, Yu. G. Sadofyev, J.-B. Wang, Y. Cao, N. Samal, C. Navarro, J. Xu, P. Dowd, S.-Q. Yu, D. Ding, Y.-H. Zhang, CW Room Temperature Operation of Long-Wavelength GaAsSb VCSELs on GaAs, Long-Wave on GaAs Technology Workshop, Napa Valley CA, June 2002.
• S. R. Johnson, M. Beaudoin, M. Boonzaayer, E. Grassi, Y.-H. Zhang, Real-Time Control of Substrate Temperature Using Band Edge Thermometry, 2000 IEEE Lasers and Electro-Optics Society (LEOS) Summer Topical Meetings, Aventura FL, July 2000.