Cross-plane Seebeck coefficient and thermal conductivity of CuFeSe2 thin film

Abstract

The CuFeSe2 is a member of the I-III-VI2 semiconductors, whereas it shows different physical properties from the chalcopyrite family, include the tetragonal structure, the small band gap ∼0.16 eV and the weak magnetic behavior. Only a few articles focused on this material in recent years. The measurements of the Seebeck coefficient and thermal conductivity of the high quality CuFeSe2 thin film could provide valuable information for its thermal application. In this report, a CuFeSe2 thin film with thickness ∼200 nm on SiO2/Si substrate was prepared by pulse laser deposition (PLD). The highly crystallized film shows a preferred orientation (h 0 0) normal to the film surface. Two pairs of heater/sensor Au strips were thermally deposited on the thin film and substrate separately for thermal conductivity measurement using differential 3ω method. The Seebeck coefficient across the film plane was directly measured by two additional EMF probes below and above the film with temperature gradient generated by heater/sensor at frequency 2ω. The temperature dependence of thermal conductivity and Seebeck coefficient were measured in a wide temperature range from 150 to 300 K. The room-temperature thermal conductivity and Seebeck coefficient are obtained to be 3.5 W/m-K and −108 μV/K respectively.