Dong Yu

Assistant Professor
Department of Physics
University of California at Davis

Office:   203 Physics
Phone:  530-554-1630
Fax:      530-752-4717
Email:   yu at physics.ucdavis.edu

2008-         Assistant Professor of Physics, University of California at Davis
2005-2008  Postdoc, Harvard University
2000-2005  Ph.D. in Physics, University of Chicago
1995-2000  B.S. in MSE, University of Science and Technology of China

Curriculum Vitae

Group Site

Research Interest

Our research group synthesizes nanostructures with vapor deposition and colloidal methods, explores physics governing charge transport in low dimensional semiconductors with advanced experimental techniques including scanning photocurrent microscopy (SPCM), Kelvin probe microscopy (KPM).

1) Narrow bandgap nanowires for solar cell applications: One-dimensional quantum confinement is of fundamental interest, and also allows for absorption and emission wavelength tunability. Narrow bandgap materials such as PbS and PbSe hold large Bohr radii, and thus are attractive candidates to realize strong exciton confinement. Narrow bandgap nanostructures have also received great attention for solar energy conversion for their multiple exciton generation and strong absorption in the infrared range of the solar energy. We have synthesized high-density PbS nanowires via vapor-liquid-solid mechanism.  Using SPCM, we determined the minority carrier diffusion length, an important parameter for solar applications, to be ~1μm in PbS nanowires.

PbS NWs            PbS SPCM

Graham, R., Miller, C., Oh, E., & Yu, D. Electric Field dependent photocurrent decay length in single lead sulfide nanowire field effect transistors. Nano Lett., 11, 717 (2011). (pdf)

2) Transition metal doped nanowires: Introducing even a small quantity of transition metal ions into semiconductors can substantially modify the electrical, magnetic and optical properties of the host materials. The incorporation of transition metal ions into nanostructures may yield even more exciting behaviors, because quantum confinement leads to significant enhancement of this short-range exchange interaction. I am particularly interested in exploring the sp-d interaction through magnetoresistive measurements of single nanowires doped with magnetic ions.

PbMnS

Isheim, D., Kaszpurenko, J., Yu, D., Mao, Z., Seidman, D., and Arslan, I., 3-D Atomic-Scale Mapping of Manganese Dopants in Lead Sulfide Nanowires. J. Phys. Chem. C, 116, 6595 (2012). (pdf)

3) Metal insulator transition in strongly correlated materials: VO2 undergoes insulator-metal transition and is one of the most studied strongly correlated materials. However, the phase transition mechanism in VO2 is still under debate even after decades of studies. Our SPCM study of VO2 nanobeams may help understand the mechanism of the insulator-metal transition. Particularly, we have investigated the electronic structure at the junction of metal-insulator domain walls in VO2 with SPCM and revealed a band bending at the domain walls.

VO2

Miller, C., Triplett, M., Lammatao, J., Suh, J., Fu, D., Wu J., & Yu, D. Unusually long free carrier lifetime and metal-insulator band offset in vanadium dioxide. Phys. Rev. B, 85, 085111 (2012). (pdf)

Publication List
15.    Isheim, D., Kaszpurenko, J., Yu, D., Mao, Z., Seidman, D., and Arslan, I., 3-D Atomic-Scale Mapping of Manganese Dopants in Lead Sulfide Nanowires. J. Phys. Chem. C, 116, 6595 (2012). (pdf)
14.    Miller, C., Triplett, M., Lammatao, J., Suh, J., Fu, D., Wu J., & Yu, D. Unusually long free carrier lifetime and metal-insulator band offset in vanadium dioxide. Phys. Rev. B, 85, 085111 (2012). (pdf)
13.    Fu, D., Zou, J., Wang, K., Zhang, R., Yu, D., & Wu, J. Electrothermal dynamics of semiconductor nanowires under local carrier modulation. Nano Lett., 11(9), 3809 (2011). (pdf)
12.    Graham, R., Miller, C., Triplett, M., & Yu, D. Scanning photocurrent microscopy in single nanowire devices. Proc. of SPIE, 8106, 81060K (2011) (Invited paper). (pdf)
 11.    Graham, R., Miller, C., Oh, E., & Yu, D. Electric Field dependent photocurrent decay length in single lead sulfide nanowire field effect transistors. Nano Lett., 11, 717 (2011). (pdf)
 10.    Yu, D., Brittman, S., Lee, J., Falk, A. L. & Park, H. Minimum voltage for threshold switching in nanoscale phase-change memory. Nano Lett. 8, 3429 (2008). (pdf)
 9.    Lee, J., Brittman, S., Yu, D. & Park, H. Vapor-liquid-solid and vapor-solid growth of phase-change Sb2Te3 nanowires and Sb2Te3/GeTe nanowire heterostructures. J. Am. Chem. Soc. 130, 6252 (2008). (pdf)
8.    Guyot-Sionnest, P., Yu, D., Jiang, P. H. & Kang, W. Spin blockade in the conduction of colloidal CdSe nanocrystal films. J. Chem. Phys. 127, 014702 (2007). (pdf)
7.    Yu, D., Wu, J., Gu, Q. & Park, H. Germanium telluride nanowires and nanohelices with memory-switching behavior. J. Am. Chem. Soc. 128, 8148 (2006). (pdf)
6.    Yu, D., Wehrenberg, B. L., Jha, P., Ma, J. & Guyot-Sionnest, P. Electronic transport of n-type CdSe quantum dot films: Effect of film treatment. J. Appl. Phys. 99, 104315 (2006). (pdf)
5.    Yu, D., Wehrenberg, B. L., Yang, I., Kang, W. & Guyot-Sionnest, P. Magnetoresistance of n-type quantum dot solids. Appl. Phys. Lett. 88, 072504 (2006). (pdf)
4.    Guyot-Sionnest, P., Wehrenberg, B. & Yu, D. Intraband relaxation in CdSe nanocrystals and the strong influence of the surface ligands. J. Chem. Phys. 123, 074709 (2005). (pdf)
3.    Wehrenberg, B. L., Yu, D., Ma, J. S. & Guyot-Sionnest, P. Conduction in charged PbSe nanocrystal films. J. Phys. Chem. B 109, 20192 (2005). (pdf)
2.    Yu, D., Wang, C. J., Wehrenberg, B. L. & Guyot-Sionnest, P. Variable range hopping conduction in semiconductor nanocrystal solids. Phys. Rev. Lett. 92, 216802 (2004). (pdf)
1.    Yu, D., Wang, C. & Guyot-Sionnest, P. n-type conducting CdSe nanocrystal solids. Science 300, 1277 (2003). (pdf)


Courses
 PHY 1A Principles of physics
PHY 9A Classical Mechanics
PHY 9C Electricity and Magnetism
PHY 110 Electricity and Magnetism (Upper division)
PHY 250 Introduction to Nanoscale Science (Graduate)