Empirical Role of Crystalline Defects in the Transport Properties of Sb<sub>2</sub>Te<sub>3</sub> Single Crystals
Indu Rajput, Devendra Kumar, Archana Lakhani
Abstract
This report emphasizes the impact of crystalline defects on the transport properties of single crystals of the topological insulator (TI) Sb 2 Te 3 . Two different single crystals S1 and S2, with slight variations in the tellurium composition are grown by the modified Bridgman method. X-ray diffraction (XRD), high-resolution X-ray diffraction (HRXRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) measurements are used to characterize the structural properties. The slight variation of “Te” has a substantial influence on the quality of the crystal structure and consequently affects the observed physical properties. Both crystals exhibit different strengths of microstrain, which were determined by the Williamson–Hall (WH) analysis. The resistivity shows a metallic behavior in the absence of a magnetic field, whereas magnetoresistance (MR) shows no sign of saturation up to 9T. The Hall resistivity demonstrates different types of charge carriers, revealing a crossover from p- to n-type behavior for S1 and S2 crystals due to the presence of varied defects. The “Te” vacancies (V Te +2 ) and “Sb” antisite (AS) defects (Sb Te –1 ) are recognized as the intrinsic defects accountable for the inherent n-type and p-type conductivities observed in Sb 2 Te 3 . By utilizing the manipulation of intrinsic defects, it becomes possible to adjust the position of the Fermi level within Sb 2 Te 3 single crystals. This development opens up new opportunities for the extensive exploration of the topological insulator behavior in Sb 2 Te 3 .