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Title: Si{sub 80}Ge{sub 20} thermoelectric alloys prepared with GaP additions

Abstract

Controlled amounts of GaP and P were added to a Si{sub 0.8}Ge{sub 0.2} matrix by a powder-metallurgical technique in order to evaluate the optimum composition for thermoelectric applications. Bulk determination of the gallium and phosphorus content in fully dense, hot pressed compacts was performed by inductively coupled plasma atomic emission spectroscopy. The transport properties of the compacts were characterized by Hall effect measurements at room temperature and by measurements of electrical resistivity, Seebeck coefficient, and thermal diffusivity to 1000 {degree}C. Considerable variation in the electrical transport properties were found to accompany changes in the Ga/P ratio, in the total amount of dopant, and changes in other preparation conditions. Alloys with gallium phosphide additions exhibit carrier concentrations higher than those obtained in alloys doped only with phosphorus. Alloys with a nominal phosphorus content greater than 2.0 at. % were found to be overdoped and those containing less than 0.6 at. % phosphorus were found to be underdoped relative to the material`s maximum figure of merit. Room temperature electron mobilities greater than 40 cm{sup 2}/V s were commonly obtained in samples with a carrier concentration of 3{times}10{sup 20} cm{sup {minus}3} or greater. A 300--1000 {degree}C integrated average figure of merit ({ital Z}={italmore » S}{sup 2}/{rho}{Lambda}) of 0.93{times}10{sup {minus}3} {degree}C{sup {minus}1} was achieved within an optimum composition range of 0.8--1.2 at. % P and 0.6--0.8 mol % GaP, which is 20% higher than current {ital n}-type Si-Ge alloys doped with 0.59 at. % P as used in the Voyager, Galileo, and Ulysses missions. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less

Authors:
; ; ;  [1]
  1. Ames Laboratory, Iowa State University, Ames, Iowa 50011-3020 (United States)
Publication Date:
Research Org.:
Ames National Laboratory
OSTI Identifier:
118397
DOE Contract Number:  
W-7405-ENG-82
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 78; Journal Issue: 9; Other Information: PBD: 1 Nov 1995
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; GERMANIUM ALLOYS; THERMOELECTRIC PROPERTIES; SILICON ALLOYS; DOPED MATERIALS; ELECTRIC CONDUCTIVITY; ELECTRON MOBILITY; GALLIUM PHOSPHIDES; HALL EFFECT; POWDER METALLURGY; SEEBECK EFFECT; THERMAL DIFFUSIVITY; NESDPS Office of Nuclear Energy Space and Defense Power Systems

Citation Formats

Cook, B A, Harringa, J L, Han, S H, and Vining, C B. Si{sub 80}Ge{sub 20} thermoelectric alloys prepared with GaP additions. United States: N. p., 1995. Web. doi:10.1063/1.359663.
Cook, B A, Harringa, J L, Han, S H, & Vining, C B. Si{sub 80}Ge{sub 20} thermoelectric alloys prepared with GaP additions. United States. https://doi.org/10.1063/1.359663
Cook, B A, Harringa, J L, Han, S H, and Vining, C B. Wed . "Si{sub 80}Ge{sub 20} thermoelectric alloys prepared with GaP additions". United States. https://doi.org/10.1063/1.359663.
@article{osti_118397,
title = {Si{sub 80}Ge{sub 20} thermoelectric alloys prepared with GaP additions},
author = {Cook, B A and Harringa, J L and Han, S H and Vining, C B},
abstractNote = {Controlled amounts of GaP and P were added to a Si{sub 0.8}Ge{sub 0.2} matrix by a powder-metallurgical technique in order to evaluate the optimum composition for thermoelectric applications. Bulk determination of the gallium and phosphorus content in fully dense, hot pressed compacts was performed by inductively coupled plasma atomic emission spectroscopy. The transport properties of the compacts were characterized by Hall effect measurements at room temperature and by measurements of electrical resistivity, Seebeck coefficient, and thermal diffusivity to 1000 {degree}C. Considerable variation in the electrical transport properties were found to accompany changes in the Ga/P ratio, in the total amount of dopant, and changes in other preparation conditions. Alloys with gallium phosphide additions exhibit carrier concentrations higher than those obtained in alloys doped only with phosphorus. Alloys with a nominal phosphorus content greater than 2.0 at. % were found to be overdoped and those containing less than 0.6 at. % phosphorus were found to be underdoped relative to the material`s maximum figure of merit. Room temperature electron mobilities greater than 40 cm{sup 2}/V s were commonly obtained in samples with a carrier concentration of 3{times}10{sup 20} cm{sup {minus}3} or greater. A 300--1000 {degree}C integrated average figure of merit ({ital Z}={ital S}{sup 2}/{rho}{Lambda}) of 0.93{times}10{sup {minus}3} {degree}C{sup {minus}1} was achieved within an optimum composition range of 0.8--1.2 at. % P and 0.6--0.8 mol % GaP, which is 20% higher than current {ital n}-type Si-Ge alloys doped with 0.59 at. % P as used in the Voyager, Galileo, and Ulysses missions. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.},
doi = {10.1063/1.359663},
url = {https://www.osti.gov/biblio/118397}, journal = {Journal of Applied Physics},
number = 9,
volume = 78,
place = {United States},
year = {1995},
month = {11}
}