Thermoelectric microstructures of Bi 2Te 3/Sb 2Te 3 for a self-calibrated micro-pyrometer

Abstract

The fabrication of thermopiles suitable for thermoelectric cooling and energy generation using Bi 2Te 3 and Sb 2Te 3 as n- and p-type layers, respectively, is reported. The thin-film thermoelectric material deposition process, thin-film electronic characterization and device simulation is addressed. The thermoelectric thin-films were deposited by co-evaporation of Bi and Te, for the n-type element and Sb and Te, for the p-type element. Seebeck coefficients of −190 and +150 μV K −1 and electrical resistivities of 8 and 15 μΩ m were measured at room temperature on Bi 2Te 3 and Sb 2Te 3 films, respectively. These values are better than those reported in the literature for films deposited by co-sputtering or electrochemical deposition and are close to those reported for films deposited by metal-organic chemical vapour deposition and flash evaporation. A small device with a cold area of 4 mm × 4 mm 2 and four pairs of p–n junctions was fabricated on a Kapton ® substrate, showing the possibility of application in Peltier cooling, infrared detection and energy generation. Small devices fabricated on a polyimide (Kapton ®) substrate and micro-devices fabricated on a silicon nitride substrate were simulated using finite element analysis. The simulations show the possibility of achieving near 20 K cooling over 1 mm 2 areas.