About the electrical conductivity of p-SixGe1-x

The specific, reduced and universal electrical conductivities of silicon/germanium is studied in this paper. Si_xGe_1-x samples with different compositions were used for research: x=0.7, 0.76 and 0.8. Their conductivity is p-type, for which they were doped with boron. The temperature dependences of reduced electrical conductivity for individual samples have the shape of a "distorted" inverted parabola i.e., they are characterized by a maximum. Based on these maximum values of reduced electrical conductivity, the maximum values of the figure of merit (ZT=σS²T/k, σ – specific electrical conductivity, S – Seebeck coefficient, T – absolute temperature and k – total thermal conductivity) of the samples can be determined. (ZT)_max can also be defined by . The Seebeck coefficient and the natural logarithm of the specific electrical conductivity are mutually proportional. Our data shows that for all three samples under study, the experimental points forms almost the single set. From this dependence you can obtain information about such important characteristics as the scattering parameter, effective mass and mobility of charge carriers.