High In-Plane Seebeck Coefficients of Bi-Sb-Te Alloy Thin Films with Growth Texture and Their Field-Controlled Seebeck Coefficients

Abstract

Bismuth antimony telluride (BixSb2-xTe3, BST) is an alloy that has widely been used over the past 5 decades for excellent p-type thermoelectric (TE) materials that operate around 300 K, for example, for electronic refrigeration and generators with other n-type TE materials, including Bi2Te3 alloy materials. However, despite significant progress in bulk materials, there has been less progress and less detailed TE information on Seebeck coefficients in the thin-film form. Here, we report reliable in-plane Seebeck coefficients of p-type Bi0.5Sb1.5Te3 (BST) films and Bi2Te3/Bi0.5Sb1.5Te3 (BT/BST) multilayer films at 300 K using a promising measurement technique with a precisely controlled temperature difference and excellent linearity. Due to the growth texture of the films, a high in-plane Seebeck coefficient of similar to 298 mu V/K was achieved in 100 nm thick BST films at 300 K, which is an increase of'similar to 224% compared to that in 200 nm thick BT/BST multilayer films. Moreover, we demonstrate field-controlled Seebeck coefficients of p-BST films by a backside gate configuration in a field-effect transistor. Our results demonstrate the importance of providing a promising measurement technique and reliable information on the in-plane Seebeck coefficients of Bi-Sb-Te alloy thin films for further TE device applications.