Electrodeposition and Characterization of p-type Sb_xTe_y Thermoelectric Thin Films

Abstract

The electro-deposition of compound semiconductors has been attracting more attention because of its ability to rapidly deposit nanostructured materials and thin films with controlled morphology, dimensions, and crystallinity in a costeffective manner (1). In particular, low band-gap A 2 B 3-type chalcogenides, such as Sb 2 Te 3 and Bi 2 Te 3 , have been extensively studied because of their potential applications in thermoelectric power generator and cooler and phase change memory. Thermoelectric Sb x Te y films were potentiostatically electrodeposited in aqueous nitric acid electrolyte solutions containing different ratios of TeO 2 to Sb 2 O 3. The stoichiometric Sb x Te y films were obtained at an applied voltage of −0.15V vs. SCE using a solution consisting of 2.4 mM TeO 2 , 0.8 mM Sb 2 O 3 , 33 mM tartaric acid, and 1M HNO 3. The stoichiometric Sb x Te y films had the rhombohedral structure with a preferred orientation along the [015] direction. The films featured hole concentration and mobility of 5.8 × 10 18 /cm 3 and 54.8 cm 2 /V•s, respectively. More negative applied potential yielded more Sb content in the deposited Sb x Te y films. In addition, the hole concentration and mobility decreased with more negative deposition potential and finally showed insulating property, possibly due to more defect formation. The Seebeck coefficient of as-deposited Sb2Te3 thin film deposited at −0.15V vs. SCE at room temperature was approximately 118 µV/K at room temperature, which is similar to bulk counterparts.