The fingerprint of Te-rich and stoichiometric Bi₂Te₃nanowires by Raman spectroscopy

Abstract

We unambiguously show that the signature of Te-rich bismuth telluride is the appearance of three new peaks in the Raman spectra of Bi2Te3, located at 88, 117 and 137 cm(-1). For this purpose, we have grown stoichiometric Bi2Te3 nanowires as well as Te-rich nanowires. The absence of these peaks in stoichiometric nanowires, even in those with the smallest diameter, shows that they are not related to confinement effects or the lack of inversion symmetry, as stated in the literature, but to the existence of Te clusters. These Te clusters have been found in non-stoichiometric samples by high resolution electron microscopy, while they are absent in stoichiometric samples. The Raman spectra of the latter corresponds to the one for bulk Bi2Te3. The intensity of these Raman peaks are clearly correlated to the Te content. In order to ensure statistically meaningful results, we have investigated several regions from every sample.

High-quality and Large-size Topological Insulator Bi2Te3-Gold Saturable Absorber Mirror for Mode-Locking Fiber Laser

“…Figure 2(a) shows three characteristic Raman peaks of BG-SAM at 60.9, 101.1, and 133.4 cm −1 , which are consistent with the A 1 1g , E 2 g , and A 2 1g vibrational modes of BT film474849, respectively. In order to evaluate the quality and uniformity of BG-SAM (sample size: ~20 × 15 mm 2 ), we collected the Raman spectra sequentially from left to right and top to bottom with total 15 different positions on the sample (inset of Fig.…”

Pulsed current-voltage electrodeposition of stoichiometric Bi2Te3 nanowires and their crystallographic characterization by transmission electron backscatter diffraction

“…The chemical composition of the nanowires was analyzed by EDX at three different areas along the cross-section of the nanowires. A recent study by Raman spectroscopy of Bi 2 Te 3 nanowires grown by our group in similar conditions shows a relation between the composition and the Raman spectroscopy, confirming that nanowires with a composition of 2:3 Bi/Te show the three active vibration modes of bismuth telluride without excess Te [17].…”

“…This process influences the crystallographic quality of the deposit and the properties of the semiconducting material obtained. This process has been studied before in our group for films [16], 1D nanowire arrays [6,17,18] and 3D Bi 2 Te 3 networks [19].…”

Three-Dimensional Bi2Te3 Networks of Interconnected Nanowires: Synthesis and Optimization

“…In order to corroborate the EDX results and to study in detail these 3D Bi 2 Te 3 nanowire networks, Raman shift measurements were performed in all samples. In a recent study by Rodriguez-Fernandez et al [ 19 ], Raman spectroscopy was employed to further investigate the presence of tellurium clusters in Bi 2 Te 3 nanowires. Taking into account that the non-stoichiometric 3D nanowire networks grown in this work presented tellurium excess, a similar study was carried out in different areas to look for possible tellurium clusters in our structures.…”