Thermoelectric Figure of Merit in a One-Dimensional Model with k4-Dispersion: An Extension of the Theory by Hicks and Dresselhaus

Motivated by the strategy developed by Hicks and Dresselhaus in a quantum wire corresponding to a single-chain model with k2-dispersion, we study a one-dimensional double-chain model with two carriers of electrons and holes, characterized by k4-dispersion. To understand the role of the enhancement of the density of state derived from k4-dispersion, we calculate an optimized dimensionless thermoelectric figure of merit (ZT) depending on the side length of the cross section, a, in the same way as discussed by Hicks and Dresselhaus. We find that ZT enhances as a decreases similarly to the results obtained in the single-chain model, while the enhancement of ZT is smaller than that of single-chain model. We discuss the reason in connection with the difference of electronic state between the single- and double-chain models.