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Chemistry and Biochemistry
University of California
230 Physical Sciences Bldg.
Santa Cruz, CA 95064
Phone: (831) 459-4002
Fax: (831) 459-2935
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Yat Li Assistant Professor of Chemistry   Office: 160 PSB Phone: (831) 459-1952 Fax: (831) 459-2935 yli@chemistry.ucsc.edu

Li Research Group Department of Chemistry University of California 1156 High Street Santa Cruz, CA 95064 Office Hours Class Times & Locations Labs: 198 PSB, (831) 459-1952

RESEARCH INTERESTS:   Experimental physical chemistry, Materials chemistry, Nanomaterials, Nanoscale photonics and electronics

The primary aim of my research is to address fundamental science in low-dimensional materials through bottom-up paradigm, specifically consists of three interrelated areas including (i) design and rational synthesis of functional nanomaterials, (ii) investigation of their fundamental properties and (iii) use these novel nanomaterials to address the scientific issues in photovoltaic, nanoscale photonics and electronics.

The fundamental part of my research is centered on the development of well-defined functional nanostructures (metals, metal oxides and semiconductors). Particular emphasis will be placed on the rational synthesis of modulated semiconductor nanowires, like axial and radial nanowire heterostructures, where the composition and/or doping, and thus the optical and electronic properties can be modulated down to the atomic level along or perpendicular to the axes of NWs, respectively. These nanomaterials can provide a versatile platform for addressing fundamental questions in chemistry and physics at quantum size regime.

Enormous surface area to volume ratio and the size associated quantum confinement effect of these novel nanostructures can lead to unique properties. The structural, chemical and physical properties of these nanomaterials will be studied using advanced electron microscopy techniques, electrical transport measurements and a variety of spectroscopic techniques. The studies not only allow optimization of nanostructures on atomic level, but also understanding of the correlation between properties and structures. The ultimate goal is to predict and tuning their fundamental properties through controlled synthetic variation of structures.

The distinctive properties of nanomaterials offer broad opportunities in addressing the critical basic science issues that are required to enable a specific technology, for example, photovoltaic, nanoscale photonics and electronics. Combined with novel device concepts and assembly techniques, nanoscale devices and systems can be developed that could lead to new functions and/or greatly enhanced performance compared to conventional bulk/planar structures.

SELECTED PUBLICATIONS

Jiang X.C., Xiong Q.H., Nam S., Qian F., Li Y. and Lieber C. M. "InAs/InP Radial Nanowire Heterostructures as High Electron Mobility Devices" Nano Lett. 7 3214 (2007)

Li Y., Qian F., Xiang J. and Lieber C. M. “Electronic and optoelectronic properties of nanowires”, Materials Today, 9 (10), 18 (2006).

Li Y., Xiang J., Qian F., Gradecak S., Wu Y., Yan H. and Lieber C. M. “Dopant-free GaN/AlN/AlGaN radial nanowire heterostructures as high electron mobility transistors”, Nano Lett. 6, 1468-1471 (2006).

Qian F.,* Gradecak S.,* Li Y.,* Wen C. Y. and Lieber C. M. “Core/multishell nanowire heterostructures as multicolor, high-efficiency light-emitting diodes”, Nano. Lett. 5, 2287-2291 (2005).

Gradecak S., Qian F., Li Y., Park H. G. and Lieber C. M. “GaN nanowire lasers with low lasing thresholds”, Appl. Phys. Lett. 87, 173111 (2005).

Greytak A. B., Barrelet C. J., Li Y. and Lieber C. M. “Semiconductor nanowire laser and nanowire waveguide electro-optic modulators”, Appl. Phys. Lett. 87, 151103 (2005). (Cover article)

Qian F.,* Li Y.,* Gradecak S.,* Wang D, Barrelet C. J. and Lieber C. M. “Gallium nitride based nanowire radial heterostructures for nanophotonic”, Nano. Lett. 4, 1975-1979 (2004).