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A1: Low temperature materials

Concentration anomalies of the thermoelectric propertiesin Bi1-xSbx solid solutions thin films 

E.I. Rogacheva,1 D.A. Orlova,1 A.N. Doroshenko,1 A.Yu. Sipatov, 1M.S. Dresselhaus,2 and S. Tang2
1National Technical University "Kharkov Polytechnic Institute", Ukraine2Massachusetts Institute of Technology, USA 

Earlier [1,2], we revealed a non-monotonic behavior of the concentration dependences of thermoelectric properties in polycrystalline Bi1-xSbx solid solutions in the vicinity of x = 0.01, 0.03 and 0.07, which indicates qualitative changes in the electronic and lattice crystal subsystems under increasing Sb concentration at the indicated compositions. We attributed the concentration anomalies to percolation effects in the solid solution, transition to a gapless state, and semimetal - semiconductor transition, respectively.

 

The goal of the present work is to establish whether the non-monotonic behavior of the concentration dependences of thermoelectric properties is observed in the thin film state as well. The Bi1-xSbx thin films with d = 300 nm were prepared by thermal evaporation of Bi1-xSbx crystals (x = 0 – 0.09) and their deposition as thin films on (111) mica substrates at temperature Тs = 380 K. It was established that the concentration anomalies of the thermoelectric properties, which we had earlier observed in bulk polycrystalline Bi1-xSbx solid solutions are reproduced in thin Bi1-xSbx films. On the one hand, this represents another evidence of the existence of concentration anomalies of the properties in the Bi1-xSbx solid solutions, and on the other hand it shows a good correspondence between the composition of solid solution used as the initial material and that of the thin film. The existence of the concentration anomalies of thermoelectric properties of Bi1-xSbx solid solutions in bulk and thin film state should be taken into account when interpreting the results of studies and predicting thermoelectric properties of Bi1-xSbx crystals and thin films as well as when developing new thermoelectric materials on their basis.

  1. E.I. Rogacheva, A.A. Drozdova, O.N. Nashchekina, M.S. Dresselhaus, G. Dresselhaus, Appl. Phys. Lett., 94 (2009) 202111.
  2. E.I. Rogacheva, A.A. Drozdova, O.N. Nashchekina, Phys. Stat. Sol. (A), 207 (2010) 344.