The thickness-induced magneto-transport and optic properties enhancement in Sb2Te3 flakes

Abstract

The electric and optical properties were studied in Sb2Te3 with different thickness. It reveals the same resistivity at measured temperatures, but shows a larger magnetoresistance ratio at thicker flakes. All measured data conformed to a linear correlation between magnetoresistance ratio which is one-order enhanced, and mobility over a wide mobility range. A higher photocurrent response is observed in thicker flakes. These results support that the thickness enhances the effective carrier mobility which leads to magneto-transport and optic properties enhancement.

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

“…The FWHM value of the main peak is 3 times larger than that of the nearly perfect strain-free silicon single crystal (0.03°, measured on the same machine ). 22 The rocking curve for S2 possesses a broad angular region and holds a shoulder of higher ω side, which shows two deconvoluted peaks with a separation of Δω = 0.276°. The generation of the second peak is mainly attributed to low-angle grain boundaries and slight misorientation from the main crystal domain.…”

“…The azimuthal ϕ-scan shown in Figure 4(b, d) exhibits three peaks at the separation of 120°, which correspond to the threefold crystal symmetry of the (015) plane, indicating in-plane orientation. 22 However, the ϕscan of S2 shows sharp peaks in contrast to S1. This indicates the existence of disorders such as mosaic twist or spread in the in-plane direction for S1.…”

“…Out-of-plane and in-plane XRD patterns support the single-crystalline nature of both crystals. The azimuthal ϕ-scan shown in Figure (b, d) exhibits three peaks at the separation of 120°, which correspond to the threefold crystal symmetry of the (015) plane, indicating in-plane orientation . However, the ϕ-scan of S2 shows sharp peaks in contrast to S1.…”

“…This expansion in the basal plane might be associated with the occurrence of vacancy-type defects in the lattice of S2. The slight increment in the ‘ c ’ of sample S1 compared to that of S2 suggests the lattice expansion along the c -axis in S1, which could be due to the intercalation of “Sb” between the QLs. − The expansion of the c -axis may also occur for (Sb Te –1 ) antisite defects, where the larger Sb occupies the Te­(I) site . As shown in Table , the gained site occupancy from the Rietveld refinement of powder XRD indicates the presence of intercalated atoms between the QLs and vacancy-type defects for S1 and S2, respectively.…”

“…12,22 For an almost strain-free crystal, the value of ϵ is ∼10 −6 . 22 However, crystal S1 possesses a large value of ϵ as compared to S2, which indicates the enhanced microstrain in crystal S1 along the c-axis. The enhanced microstrain is further supported by the higher value of the lattice parameter "c" in S1 and a large proportion of "Sb" in EDX, which also suggests the intercalation of "Sb" atoms in between the Sb 2 Te 3 QLs.…”