Deposition potential controlled structural and thermoelectric behavior of electrodeposited CoSb3 thin films

Abstract

In this study, the deposition potential has been used to exercise control on structural and electrical properties, and associated tuning of thermoelectric properties of CoSb₃ thin films prepared by electrochemical synthesis. Deposition potential is observed to have a strong effect on the stoichiometry of films and orientation of crystallites, and consequently on the physical properties. X-ray diffraction patterns reveal that the films grown at lower deposition potentials (≤−0.9 V) have (013) preferred orientation whereas (420) orientation is observed at higher negative deposition potentials. A correlation of the deposition potential controlled composition from a Sb-rich to a Co-rich regime and the resulting tuning of electrical transport parameters and thermoelectric properties of the CoSb₃ thin films is established. With enlarged crystallites and enhanced textured structure at a deposition potential of −0.97 V, a significantly large Seebeck coefficient (58 μV K⁻¹) with a simultaneously large electrical conductivity (2.1 × 10³ Ω⁻¹ cm⁻¹) are achieved as a result of the high mobility (60 cm² V⁻¹ s⁻¹). A high value for room temperature power factor (706 ± 9 μW K⁻² m⁻¹) observed in the as-grown CoSb₃ thin films without any further post-deposition annealing makes their synthesis and thermoelectric studies interesting for their potential applications in power generation and refrigeration.