Thermal and Electrical Properties of Heavily Doped Ge-Si Alloys up to 1300°K

Abstract

The thermal resistivity, Seebeck coefficient, electrical resistivity, and Hall mobility of Ge‐Si alloys have been measured throughout the Ge‐Si alloy system as functions of impurity concentration in the range 2×10¹⁸−4×10²⁰cm⁻³, and of temperature in the range 300°–1300°K. A qualitative interpretation of these properties is given. For power conversion, boron and phosphorus were found to be useful p‐type and n‐type impurities, respectively, because of their high solid solubilities. At 1200°K, the maximum values of the dimensionless figure of merit zT were 0.8 for p‐type Ge_0.15‐Si_0.85 alloy doped to 2.1×10²⁰cm⁻³ holes, and 1.0 for n‐type Ge_0.15‐Si_0.85 alloy doped to 2.7×10²⁰cm⁻³ electrons. The maximum over‐all efficiency of a stable generator operating between 300°–1200°K, using the best p‐type and n‐type materials was computed to be 10%.