TRANSIENT THERMOELECTRIC EFFECT IN BISMUTH SINGLE-CRYSTALS

The photo-induced transient thermoelectric effect (TTE) has been measured for bismuth single crystals along nearly tbe X and Y axes over the temperature range 6-300 K and time range 50 ns-2 ms. The decay curves of the TTE voltages are characterized by multiple relaxation processes for thermal diffusions of photogenerated electrons and holes. From the analysis of the relaxation times, we have evaluated the carrier mobilities and their effective masses of each carrier pocket at the L and T points based on the existing band model; in particular, we have found an additional hole pocket at the L point lying below the Fermi energy. This TTE technique is shown to be useful for understanding electronic properties of a multicarrier system.