Empirical Role of Crystalline Defects in the Transport Properties of Sb₂Te₃ Single Crystals

Abstract

This report emphasizes the impact of crystalline defects on the transport properties of single crystals of the topological insulator (TI) Sb2Te3. 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 (VTe +2) and “Sb” antisite (AS) defects (SbTe –1) are recognized as the intrinsic defects accountable for the inherent n-type and p-type conductivities observed in Sb2Te3. By utilizing the manipulation of intrinsic defects, it becomes possible to adjust the position of the Fermi level within Sb2Te3 single crystals. This development opens up new opportunities for the extensive exploration of the topological insulator behavior in Sb2Te3.

Correlating the Anisotropic Etching Behavior in Layered Chalcogenide Sb2Te3 with Crystal Defect Distribution

“…For Sb 2 Te 3 , it is possible to achieve either hole-dominated or electron-dominated conduction behavior, depending on the defect type . From the perspective of atomic desorption, under the tellurium-deficient atmosphere, the formation of tellurium vacancies ( V Te ) is easier when compared to the Sb vacancies ( V Sb ) because of the higher saturation vapor pressure of tellurium .…”

“…For Sb 2 Te 3 , it is possible to achieve either hole-dominated or electron-dominated conduction behavior, depending on the defect type. 38 From the perspective of atomic desorption, under the tellurium-deficient atmosphere, the formation of tellurium vacancies (V Te ) is easier when compared to the Sb vacancies (V Sb ) 39 because of the higher saturation vapor pressure of tellurium. 40 Thus, we infer that along the crystallographic orientations perpendicular to the high-energy {101̅ 0} facets, the weakly bounded tellurium atoms are easily volatile, resulting in the higher carrier density, as schematically shown in Figure 3h.…”

Tuning of thermoelectric performance by modulating vibrational properties in Ni-doped Sb2Te3

“…West et al estimated the formation energy of native point defects in Sb 2 Te 3 from first principles calculations, which is in the following order Sb Te < V Sb < V Te . Due to the presence of a prevailing amount of Sb Te -type AS defects, which donate holes into the system, pristine Sb 2 Te 3 is always p-type in nature [64,65]. On the other hand, V Sb , having the second lowest formation energy, donates electrons in the system [64].…”