| AVS 57th International Symposium & Exhibition | |
| Actinides and Rare Earths Topical Conference | Tuesday Sessions |
| Session AC-TuA |
| Session: | Science and Technology of Actinides and Rare Earths |
| Presenter: | T. Onishi, University of California, Santa Cruz and NASA Ames Research Center |
| Authors: | T. Onishi, University of California, Santa Cruz and NASA Ames Research Center T. Favaloro, University of California, Santa Cruz A. Shakouri, University of California, Santa Cruz and NASA Ames Research Center E. Coleman, Structured Materials Industries Inc. G.S. Tompa, Structured Materials Industries Inc. S. Kraemer, University of California, Santa Barbara H. Lu, University of California, Santa Barbara A. Gossard, University of California, Santa Barbara N.P. Kobayashi, University of California, Santa Cruz and NASA Ames Research Center |
| Correspondent: | Click to Email |
The increasing demand for efficiency in energy generation and use has increased interest in thermoelectrics (the direct conversion of heat to electricity), which has the promise to increase energy efficiency – if certain cost-performance metrics are met. However, in the continuing quest of the efficient bulk thermoelectrics material for more than 50 years, the improvement of thermoelectric properties has not been sufficient to widely replace other established power sources.
One of the promising lines of new material development is based on the use of nanostructures to dramatically change the heat transport properties of thermoelectrics while largely leaving the electrical properties in tact. In this effort we have focused on developing nanocomposites comprised of thin films containing semi-metallic nanocrystals. We herein report on the growth of nanocomposites that consist of erbium monoantimonide (semi-metal) in the form of nano crystals or nanocolumns self-assembled with in thin film group III- arsenide/antimonide alloys doped with acceptors. The nano composites are optimized in terms of three factors, electrical conductivity, and thermal conductivity, and Seebeck coefficient to maximize thermoelectric figure of merit.
Using low-pressure metal organic chemical vapor deposition (MOCVD), we have developed the growth processes of the nanocomposites that consist of indium gallium (arsenic) antimonide (InGa(As)Sb) host materials with embedded erbium antimonide (ErSb) nanocrystals. The size of ErSb nano crystals, carrier density and alloy composition of the InGa(As)Sb host materials are tuned by controlling of various growth parameters. The following techniques were used to obtain information on the growth of ErSb nanocomposites embedded InGa(As)Sb film on n-type InSb (100) substrate: Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red-absorption (FTIR), Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM).
Acknowledgement:
This research is funded by DARPA and DOE ; supported by Structured Materials Industries Inc. [www.structuredmaterials.com] for the growth; Advanced Studies Laboratories in NASA Ames research Center, and Materials Department, University of California, Santa Barbara for the characterization.