• Arizona State University, Tempe, Arizona, Ph.D. in Electrical Engineering, November 2005.

• Arizona State University, Tempe, Arizona, Postdoctoral Research Associate, December 2005-Janauary 2007.

February 1, 2007 – present: Assistant Research Professor, Arizona State University, Center for Nanophotonics, Arizona Institute of Nano-Electronics, Tempe, AZ.

December 16, 2005 - January 31, 2007: Postdoctoral Research Associate, Arizona State University, Center for Solid State Electronics Research, Tempe, AZ.

August 2000 - December 15, 2005: Graduate Research Associate, Arizona State University, Center for Solid State Electronics Research, Tempe, AZ.

• Theoretical investigation of the fundamental mechanisms in semiconductor electroluminescence refrigeration; design and fabrication devices; development of novel characterization techniques for optical refrigeration devices.

• Independently designed and constructed unique time resolved luminescence spectroscopy measurement system (1 ns time resolution, 400 nm to 25 µm wavelength range, 10 to 400 K tem-perature range, electroluminescence and photoluminescence capability, user friendly).

• Demonstration of first RT CW GaAsSb/GaAs edge-emitting laser; development of high perform-ance VCSELs and RCLEDs; material and device characterization, device modeling, and design optimization, improve device performance to meet industry standards.

12 S.-Q. Yu, D. Ding, J.-B. Wang, N. Samal, S. R. Johnson, Y.-H. Zhang, High performance GaAsSb/GaAs quantum well lasers, J. Vac. Sci. Technol. B (Submitted April 2007).

11 S.-Q. Yu, J.-B. Wang, S. R. Johnson, D. Ding, D. Vasileska, Y.-H. Zhang, Impact of electronic density of states on electroluminescence refrigeration, Solid State Electronics (Submitted March 2007).

10 J.-B. Wang, D. Ding, S. R. Johnson, S.-Q. Yu, and Y.-H. Zhang, Determination and improvement of spontaneous emission quan-tum efficiency in GaAs/AlGaAs heterostructures grown by mo-lecular beam epitaxy, Phys. stat. sol. (a) (Submitted November 2006).

9 S. R. Johnson, D. Ding, J.-B. Wang, S.-Q. Yu, and Y.-H. Zhang, Excitation Dependent Photolumines-cence Measurements of the Nonradiative Lifetime and Quantum Efficiency in GaAs, J. Vac. Sci. Technol. B (Accepted).

8 D. Ding, S. R. Johnson, J.-B. Wang, S.-Q. Yu, Y.-H. Zhang, Intrinsic Irreversibility in Semiconductor Light Emission, Phys. stat. sol. (c) 4, No. 5, 1698–1701 (2007).

7 K. Hild, S. Wright, D. Lock, S. Jin, I. Marko, S. Sweeney, S. R. Johnson, S. Chaparro, S.-Q. Yu, and Y.-H. Zhang, Carrier recombination in 1.3µm GaAsSb/GaAs Quantum Well Lasers, Appl. Phys. Lett. 89, 173509 (2006).

6 J.-B. Wang, S. R. Johnson, D. Ding, S.-Q. Yu, Y.-H. Zhang, Influence of photon recycling on cooling efficiency and cooling power in semiconductor luminescence refrigeration, J. Appl. Phys. 100, 043502 (2006).

5 S.-Q. Yu, X. Jin, S. R. Johnson, Y.-H. Zhang, Gain Saturation and Carrier Distribution Effects in Mo-lecular Beam Epitaxy Grown GaAsSb/GaAs Quantum Well Lasers, J. Vac. Sci. Technol. B 24, 1617 (2006).

4 N. Samal, S. R. Johnson, D. Ding, A. K. Samal, S.-Q. Yu, Y.-H. Zhang, High-Power Single-Mode Ver-tical-Cavity Surface-Emitting Lasers, Appl. Phys. Lett. 87, pp161108-1, (2005).

3 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 Ap-plications, J. Crystal Growth 251, 521 (2003).

2 D.-S. Jiang, J.-B. Wang, X.-G. Liang, Z.-B. Chen, S.-Q. Yu, Y. Cao, Y.-H. Zhang, C. Navarro, S. Chaparro, S. R. Johnson, LUMINESCENCE PROPERTIES OF GaAsSb/GaAs QUANTUM WELL LA-SER STRUCTURES, JOURNAL OF INFRARED AND MILLIMETER WAVES, Vol.21 No.z1 P.7-10 (2002).

1 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).

Palais Outstanding Doctoral Student Award, ASU Electrical Engineering Department. Selected out of 41 Ph.D students that graduated in 2005.