Abstract
In the current work, growth and thermoelectric characterization of tin and selenium co-doped single crystal bismuth telluride have been carried out in the range of temperature 10–400 K. The crystals show hexagonal crystal structure with Roverline{3 }m space group. The direction of growth, quality of the single crystals, the density of dislocation, and dopants effect on the inner plane structure of the crystals have been analyzed through high-resolution X-ray diffraction study. Energy dispersive analysis of X-rays approves the elemental composition, and field emission scanning electron microscopy shows uniform growth with micro precipitates on the surface of the crystals. Quasi degenerate and non-degenerate electrical resistivity is observed in the pristine and doped samples, respectively. Temperature-dependent Seebeck coefficient measurements confirm the n-type semiconducting nature of the pristine as well as doped samples. Temperature-dependent power factor of (Bi0.96Sn0.04)2Te2.7Se0.3 is found to increase by 1.1 times, and electrical resistivity reduced by 3.3 times as compared to pristine Bi2Te3.
Highlights
Thermoelectric materials/devices have attracted huge global attention to waste heat utilization, converting heat energy into electrical energy and vice versa [1]
The quality of the thermoelectric materials are estimated using the thermoelectric figure of merit (ZT = SK2qT) where S is the Seebeck coefficient, T is the temperature, K is the thermal conductivity and q is the electrical resistivity [3]
The crystalline perfection, symmetries, dislocations, and dopants influence on the inner plane structure of the single crystals were determined using high-resolution X-ray diffraction (HR-XRD) study
Summary
Thermoelectric materials/devices have attracted huge global attention to waste heat utilization, converting heat energy into electrical energy and vice versa [1]. Bismuth chalcogenides are the vital materials utilized in low and near room temperature thermoelectric power converters [2]. Bi2Te3 and Bi2Se3 are considered suitable thermoelectric materials for low and near room temperature applications because of their electronically active antisite defects, which influence the co-factors like carrier concentration, mobility, bandgap, and activation energy [4, 5]. The point defects, low angle grains, and tilts are the major disorders in the melt-grown Bi2Te3 single crystals, and they have a significant influence on the thermoelectric properties. Sn behaves as acceptor-like impurity in Bi2Te3 generating quasi-local states situated on the background of conduction electrons. Due to presence of large number of grain boundaries, polycrystalline bismuth chalcogenide sintered compounds fail to perform selective phonon scattering, unlike the single crystals. Sn and Se co-doped single crystal bismuth telluride grown by melt-grown technique
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