Signature of weak-antilocalization in sputtered topological insulator Bi2Se3 thin films with varying thickness

Abstract

We report a low-temperature magneto transport study of Bi2Se3 thin films of different thicknesses (40, 80 and 160 nm), deposited on sapphire (0001) substrates, using radio frequency magnetron sputtering technique. The high-resolution x-ray diffraction measurements revealed the growth of rhombohedral c-axis {0003n} oriented Bi2Se3 films on sapphire (0001). Vibrational modes of Bi2Se3 thin films were obtained in the low wavenumber region using Raman spectroscopy. The surface roughness of sputtered Bi2Se3 thin films on sapphire (0001) substrates were obtained to be ~ 2.26–6.45 nm. The chemical and electronic state of the deposited Bi2Se3 was confirmed by X-ray photoelectron spectroscopy and it showed the formation of Bi2Se3 compound. Resistivity versus temperature measurements show the metallic nature of Bi2Se3 films and a slight up-turn transition in resistivity at lower temperatures < 25 K. The positive magneto-resistance value of Bi2Se3 films measured at low temperatures (2–100 K) confirmed the gapless topological surface states in Bi2Se3 thin films. The quantum correction to the magnetoconductivity of thin films in low magnetic field is done by employing Hikami–Larkin–Nagaoka theory and the calculated value of coefficient ‘α’ (defining number of conduction channels) was found to be 0.65, 0.83 and 1.56 for film thickness of 40, 80 and 160 nm, respectively. These observations indicate that the top and bottom surface states are coupled with the bulk states and the conduction mechanism in Bi2Se3 thin films varied with the film thicknesses.

Enhanced Photoresponse of High Crystalline Bi2Se3 Thin-Films Using Patterned Substrates

“…Here, 4F5/2- and 4F7/2-related signals were recorded as distinct peaks at 163.03 and 157.73 eV, respectively, and the shoulder peaks related to the Bi were observed at 161.58 and 156.08 eV. , Figure b reveals the core-level spectrum corresponding to Se 3d. Here, 3d3/2- and 3d5/2-related signals were recorded as distinct peaks at 53.6 and 52.8 eV, respectively. − The observed signals are in good agreement with previously reported results for Bi 2 Se 3 thin films, confirming the formation of high-quality crystals in Bi 2 Se 3 thin films synthesized on the PSS.…”

Roles of surface and bulk states in giant magnetoresistance and anomalous hall effect in antiferromagnetically ordered Bi1.9Dy0.1Te3topological insulators

“…2(b), which is consistent with previous reports. 26,27 The core-level XPS spectra corresponding to Te-3d 5/2 and Te-3d 3/2 are found around 572.4 eV and 582.8 eV with 10.4 eV splitting for our system as exhibited in Fig. 2(c), which is also reliable as reported in previous reports.…”

Broadband Optical Properties of Bi2Se3

“…The XPS signal in Figure 1d,e shows a rich spectrum with Biand Se-related peaks, and a quantitative XPS analysis based on Bi4f and Se3d showed that the stoichiometry of the film reached ∼43%:57%, close to the expected 40%:60% (2 Bi: 3 Se) [52][53][54][55]. According to the previous studies of Bi 2 Se 3 , the peak Se 0 (Figure 1e) indicates elemental selenium (Se) [55][56][57]. Additionally, we performed Raman spectroscopy (Figure 1f,g) at two excitation wavelengths: 532 nm (Figure 1f) and 632.8 nm (Figure 1g).…”