"We synthesize and study heterostructured nanomaterials with tunable size, shape, and lattice strain to develop new nano- and macro-electronics and solar energy conversion systems."

Moonsub Shim

Moonsub Shim
Associate Professor of Materials Science
and Engineering, Willett Faculty Scholar

Office 4105 Materials Science and Engineering Building

Telephone 217-333-7361 Fax 217-333-2736

Mail Address Department of Materials Science and Engineering
1304 W. Green St., Urbana, IL 61801

mshim@illinois.edu    Shim research group page

  • Profile
  • Research
  • Publications
  • Awards

Profile

Professor Moonsub Shim received his B.S. degree from the University of California at Berkeley in 1997 and his M.S. and Ph.D. degrees both from the University of Chicago in 1998 and 2001. After working as a postdoctoral researcher at Stanford University, he joined the faculty of the Department of Materials Science and Engineering at Illinois in 2002. Recognitions for his achievements include the Xerox Award for Faculty Research (2007), National Science Foundation CAREER Award (2004), Racheff Assistant Professorship (2002-2004), and the Willett Faculty Scholar Award (2010-2014).

Research

The overarching goal of our research program is to develop novel nanoscale materials and understand charging and charge separation phenomena occurring in them. Charging and charge separation are fundamental processes that govern how electronic, optoelectronic, and photovoltaic devices operate. Materials with nanometer dimensions provide new engineering paradigms and prospects for devices with unprecedented performance. However, ubiquitously large surface-to-volume ratio of materials in this size regime often leads to large deviations from the expected and therefore difficulties arise in achieving the desired performance. The ability to control surface and interfacial effects is then critical in elucidating the underlying materials’ properties which in turn is essential in developing any future technologies. Hence, we study how charging and charge separation processes affect structure, electrical and optical properties, and chemical reactivity with special attention to the materials’ responses to variations at surfaces and interfaces. Insights gained from these studies are then exploited to develop new materials exhibiting superior properties useful for solar energy conversion and high performance nano- and macro-electronics. 

With continuing scale down of electronic devices, increasing influence of the surface and interactions with the surrounding environment are inevitable and often present a major challenge. From device performance limits to thermal management, understanding how such extrinsic factors affect fundamental processes such as charging, electron-phonon coupling and energy relaxation/dissipation is fundamentally important. Due to their atomic thickness, carbon nanotubes and graphene are interesting platforms to examine how local chemical environments affect these fundamental processes. Such studies, in turn, may provide effective means of controlling device characteristics. By examining and controlling “hetero” interfaces of low-dimensional graphitic carbon with substrates and other surrounding media, we are developing new routes to integrating them into next generation electronics.

High quality epitaxial heterointerfaces and delicately controlled shape anisotropy can be achieved with versatile and scalable wet chemical synthesis of semiconductor nanocrystal heterostructures. Such heterostructures with tunable electronic structure and anisotropic shapes are being developed in our laboratory. Their band gaps, band offsets and the resulting optical and electrical properties are tunable through quantum confinement, composition and lattice strain effects. Anisotropic shapes are especially useful as they provide directionality in extracting/injecting carriers. These salient features of anisotropic nanocrystal heterostrctures are being exploited to develop high performance optoelectronics and photovoltaics.

Carbon Nanoelectronics carbon nanoelectronics

Nanocrystal Heterostructuresnanocrystal heterostructures

Publications

A complete list can be found at: http://shimlab.matse.illinois.edu/publications.html

C. –L. Tsai, F. Xiong, E. Pop, and M. Shim, “Carbon Nanotube Crossbar Electrode Enabled Low-Power Resistive Random Access Memory (RRAM) with sub-5 nm Bit Size,” ACS Nano, in press (2013).

C. Baeumer, S. Rogers, R. Xu, L. W. Martin, and M. Shim, “Tunable Carrier Type and Density in Graphene/PbZr0.2Ti0.8O3 Hybrid Structures through Ferroelectric Switching,” Nano Lett. 13, 1693 – 1698 (2013).

H. McDaniel, M. Pelton, N. Oh, and M. Shim, “Effects of Lattice Strain and Band Offset on Electron Transfer Rates in Type II Nanorod Heterostructures,” J. Phys. Chem. Lett. 3, 1094 – 1098 (2012).

H. McDaniel, N. Oh, and M. Shim, “CdSe/CdSexTe1-x Nanorod Heterostructures: Tuning Alloy Composition and Spatially Indirect Recombination Energies,” J. Mater. Chem. 22, 11621 – 11628 (2012).

M. Shim, H. McDaniel, and N. Oh, “Prospects for Strained Type II Nanorod Heterostructures,” J. Phys. Chem. Lett. 2, 2722 – 2727 (2011). Invited Perspective.

H. McDaniel, P. E. Heil, C. -L. Tsai, K. Kim, and M. Shim, “Integration of Type II Nanorod Heterostructures into Photovoltaics,” ACS Nano, 5, 7677 – 7683 (2011).

C. –L. Tsai, A. Liao, E. Pop, and M. Shim, “Electrical Power Dissipation in Carbon Nanotubes on Single Crystal Quartz and Amorphous SiO2,” Appl. Phys. Lett.  99, 053120 (2011).

K. T. Nguyen, D. Abdula, C. -L. Tsai, and M. Shim, “Temperature and Gate Voltage Dependent Raman Spectra of Single Layer Graphene,” ACS Nano, 5, 5273 – 5279 (2011).

D. Abdula, K. T. Nguyen, K. Kang, S. Fong, T. Ozel, D. G. Cahill, and M. Shim, “Influence of Defects and Doping on Optical Phonon Lifetime and Raman Linewidth in Carbon Nanotubes,” Phys. Rev. B 83, 205419 (2011).

S. Unarunotai, J. C. Koepke, C. –L. Tsai, F. Du, C. E. Chialvo, Y. Murata, R. Haasch, I. Petrov, N. Mason, M. Shim, J. Lyding, J. A. Rogers, “Layer-by-Layer Transfer of Large Area Sheets of Graphene Grown in Multilayer Stacks on Single SiC Wafer,” ACS Nano 4, 5591 – 5598 (2010).

M. Shim and H. McDaniel, “Anisotropic Nanocrystal Heterostructures: Synthesis and Lattice Strain,” Curr. Op. Sol. State Mater. Sci. 14, 83 – 94 (2010). Invited review article.

S. Kim, S. Kim, D. B. Janes, S. Mohammadi, J. Back, and M. Shim, “DC Modeling and the source of flicker noise in passivated carbon nanotube transistors,” Nanotechnology 21, 385203 (2010).

H. McDaniel, J. –M. Zuo, and M. Shim, “Anisotropic Strain Induced Curvature in Type II CdSe/CdTe Nanorod Heterostructures,” J. Am. Chem. Soc. 132, 3286 – 3288 (2010).

K. Kang, D. Abdula, D. G. Cahill, and M. Shim, “Lifetimes of optical phonons in graphene and graphite by time-resolved incoherent anti-Stokes Raman scattering,” Phys. Rev. B 81, 165405(2010).

K. H. Hsu, J. H. Back, K.-H. Fung, P. M. Ferreira, M. Shim, and N. X. Fang, “SERS EM-field Enhancement Study through Fast Raman Mapping of Optical Sierpinski Carpet Fractals,” J. Raman Spectr. 41, 1124 – 1130 (2010).

J. H. Back, C. –L. Tsai, S. Kim, S. Mohammadi, and M. Shim, “Manifestation of Kohn Anomaly in 1/f Fluctuations in Metallic Carbon Nanotubes,” Phys. Rev. Lett. 103, 215501 (2009).

K. T. Nguyen and M. Shim, “Role of covalent defects on phonon softening in metallic carbon nanotubes,” J. Am. Chem. Soc. 131, 7103 (2009).

T. Ozel, D. Abdula, E. Hwang, and M. Shim, “Nonuniform Compressive Strain in Horizontally Aligned Single-Walled Carbon Nanotubes Grown on Single Crystal Quartz,” ACS Nano 3, 2217 (2009).

H. McDaniel and M. Shim, “Size and Growth Rate Dependent Structural Diversification of Fe3O4/CdS Anisotropic Nanocrystal Heterostructures,”  ACS Nano 3, 434 (2009).

W.J. Huang, J.M. Zuo, B. Jiang, K.W. Kwon and M. Shim, “Sub-Å resolution diffractive imaging of single nanocrystals,” Nature Phys. 5, 129 (2009).

S. Kim, S. Ju, J. H. Back, Y. Xuan, P. D. Ye, M. Shim, D. B. Janes, and S. Mohammadi, “Fully Transparent Thin-Film Transistors Based on Aligned Carbon Nanotube Arrays and Indium Tin Oxide Electrodes,” Adv. Mater. 21, 564 (2009).

Awards
  • Elizabeth R. Norton Prize, U. of Chicago (2000)
  • Racheff Assistant Professor (2002-2004)
  • NSF CAREER Award (2004)
  • Xerox Award for Faculty Research (2007)
  • Willett Faculty Scholar (2010-)