Nanoindentation of single‐crystal Bi₂Te₃ topological insulators grown with the Bridgman–Stockbarger method

Abstract

In this work, bismuth telluride (Bi 2 Te 3 ) single crystals were grown from melted polycrystalline Bi-Te material using the Bridgman-Stockbarger method. Crystalline quality and surface chemistry were investigated through X-ray diffraction analysis and X-ray photoelectron spectroscopy. The mechanical properties were investigated by means of depth-sensing nanoindentation tests carried out using the continuous stiffness measurement (CSM) technique. In turn, the distribution of material hardness and Young's modulus in the depth direction (i.e., perpendicular to the single crystal basal plane) were resolved and quantitative comparisons with the available data extracted from previous literature works were drawn. It is shown that the obtained single crystals are free of contaminants and/or oxide phases and that the mechanical properties lie between those reported in recent literature for Bi 2 Te 3 polycrystalline thin films and 2D nanosheets.

Effects of Substrate Temperature on Nanomechanical Properties of Pulsed Laser Deposited Bi2Te3 Films

“…This means that both the values of H and Ef of the Bi2Te3 thin films m otonically decrease with increasing TS. Noticeably, the H and Ef of the present Bi2Te3 films are significantly larger than that reported for the bulk Bi2Te3 (H = 1.6 ± 0.2 GPa E = 32.4 ± 2.9 GPa) [22]. The reason for the apparent discrepancy is not clear at pre Nevertheless, by comparing the results of the films in this study with that reported in [23], the stoichiometric levels and crystallite orientation of the films may have inti correlations with the H and Ef results.…”

Elastic constants determination of anisotropic materials by depth-sensing indentation

“…3D topological insulators are considered a novel topological phase of matter, and are gaining growing interest from the worldwide scientific community [16][17][18], due to their promising applications in optoelectronics [19], plasmonics [20], spintronics [21], quantum computing [22], and thermoelectric devices [17,23,24]. Bi 2 Te 3 and Bi 2 Se 3 represent the most studied topological insulators, due to their large energy gap (~ 0.2-0.3 eV) that allows applications at room temperature [15,[25][26][27][28][29]. In this section we focus on Bi 2 Te 3 , a layered and anisotropic material, whose atomic structure is illustrated in Fig.…”

“…For both the directions parallel and perpendicular to the Bi 2 Te 3 lamellae, the experimental indentation modulus M E stabilizes when the penetration depth reaches a value of 120 nm. The stabilization is obtained only when the condition of full plasticity contact is satisfied, as discussed in [28].…”

THERMODYNAMİC PROPERTİES OF THE Bi2Te3 AND Bi4Te5 COMPOUNDS

“…Bismuth tellurides, especially Bi 2 Тe 3 , phases, and composites based on it have long been in the field of view of researchers as valuable thermoelectric materials [1][2][3]. After the discovery of a special quantum state of mattera topological insulator (TI) [4], it was found that Bi2Te3 and many other layered compounds of tetradimite-like structures are TI which are rather promising for their varied applications [5][6][7][8][9][10][11]. In particular, the unique optical properties make them promising for the use in broadband optoelectronics as photodetectors [12][13][14][15].…”