Doping of Thermoelectric Nanostructured Solid Solution Si1 – xGex (x ~ 0.3) with Donor and Acceptor Impurities during the Synthesis Process by Spark Plasma Sintering

The work examines the doping of a Si1 – xGex solid solution with donor (Sb, P) and acceptor (B) impurities during the synthesis process using electric pulse plasma sintering from powders with submicron particle sizes. The impurity content varied from 0.5 to 2.0 at %. Using the methods of X-ray diffraction, scanning electron microscopy, and X-ray microanalysis, it has been shown that the introduction of an impurity into a solid solution obeys the laws of equilibrium solubility; in particular, when the solubility limit is exceeded, precipitates of the impurity material are formed in the matrix of the material. This fact seems interesting, since electric pulse plasma sintering as a synthesis method is considered nonequilibrium. Studies of thermoelectric properties show that the selection of doping conditions makes it possible to form materials for which, despite the presence of impurity phase inclusions, high values of the thermoelectric figure of merit comparable to the world level of results can be obtained.