AVS 56th International Symposium & Exhibition
    Electronic Materials and Processing Tuesday Sessions
       Session EM1+PV-TuM

Paper EM1+PV-TuM3
Synthesis of PbTe Nanowires by Lithographically Patterned Nanowire Electrodeposition (LPNE) and Their Thermoelectric Properties

Tuesday, November 10, 2009, 8:40 am, Room A8

Session: High Efficiency and Quantum Structure Photovoltaics
Presenter: Y. Yang, University of California, Irvine
Authors: Y. Yang, University of California, Irvine
D.K. Taggart, University of California, Irvine
R.M. Penner, University of California, Irvine
S.C. Kung, University of California, Irvine
F. Yang, University of California, Irvine
C.X. Xiang, University of California, Irvine
M.A. Brown, University of California, Irvine
J.C. Hemminger, University of California, Irvine
Correspondent: Click to Email
Thermoelectric materials have received renewed interest in the past decade stemming from theoretical calculations that one-dimensional thermoelectric materials (i.e., nanowires) should show a remarkable enhancement in the dimensionless figure of merit—ZT caused by enhanced Seebeck coefficients, electrical conductivities and/or depressed thermal conductivities relative to their bulk counterparts. The prediction has been verified recently on silicon single-crystalline nanowire-arrays that showed almost one hundred times of enhancement of ZT. In contrast, there has not been anydemonstration of a similar effect on PbTe nanowires—one of the best thermoelectric materials in bulk. This presentation reports a synthesismethod called lithographically patterned nanowire electrodeposition (LPNE) for making PbTe nanowires and characterization of their thermoelectricproperties. The nanowires are semi-rectangular in cross-section with width and height independently controlled from 60 to 500 nm and from 10 to 100nm respectively, and they are electrically continuous up to millimeters. The structure and chemical composition of the nanowires are characterizedwith X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electrical conductivity and Seebeck coefficient are measured at variable temperatures. A method for making suspended nanowires cross an air gap is also developed, which iscrucial for measurement of thermal conductivity. Ag-doped PbTe nanowires synthesized by the same method demonstrate tunable thermoelectric

properties due to the modification of the carrier type and concentration.