The Modeling and Characterization of III-V Compound Semiconductors, Alloys and Nanocomposites for Thermoelectric Applications.

摘要

The field of thermoelectricity has seen a resurgence of interest of late in the quest for an efficient, compact, renewable energy source. It is important to compute accurately the Seebeck coefficient and mobility of typical n- and p- type thermoelectric materials like InGaAs and InGaSb, and to benchmark the computations against experimental data. To that end, we formulate the Boltzmann Transport Equation (BTE) for the low-field transport problem as an integral equation, and solve it by numerical iteration. We present an algorithm for extracting the Seebeck coefficient from the solution to the BTE. This procedure helps us calculate transport coefficients without the need for common simplifying assumptions like the relaxation time approximation or the neglect of inter-band scattering in p- type materials. Doping InGaAs and InGaSb with rare-earth elements like Erbium beyond the solid solubility limit is expected to increase the thermoelectric power factor, defined as S 2sigma where S is the Seebeck coefficient and sigma is the electrical conductivity. We examine the effectiveness of doping with various rare-earth elements by comparing with appropriate controls. Low thermal conductivity is an important requirement for efficient thermoelectric materials; we discuss briefly a popular technique of measuring thermal conductivity of thin films and substrates.