Anab initioinvestigation of Bi₂Se₃topological insulator deposited on amorphous SiO₂

Abstract

We use first-principles simulations to investigate the topological properties of BiSe thin films deposited on amorphous SiO, BiSe/a-SiO, which is a promising substrate for topological insulator (TI) based device applications. The BiSe films are bonded to a-SiO mediated by van der Waals interactions. Upon interaction with the substrate, the BiSe topological surface and interface states remain present, however the degeneracy between the Dirac-like cones is broken. The energy separation between the two Dirac-like cones increases with the number of BiSe quintuple layers (QLs) deposited on the substrate. Such a degeneracy breaking is caused by (i) charge transfer from the TI to the substrate and charge redistribution along the BiSe QLs, and (ii) by deformation of the QL in contact with the a-SiO substrate. We also investigate the role played by oxygen vacancies ([Formula: see text]) on the a-SiO, which increases the energy splitting between the two Dirac-like cones. Finally, by mapping the electronic structure of BiSe/a-SiO, we found that the a-SiO surface states, even upon the presence of [Formula: see text], play a minor role on gating the electronic transport properties of BiSe.

Confinement and fermion doubling problem in Dirac-like Hamiltonians

“…The conductance peaks reflect the degeneracy of the states, which are directly affected by the symmetry breaking discussed previously. In the leads, the hybridization between the topmost QLs Bi 2 Se 3 and the metal [51] puts the chemical potential within an energy window composed of Bi 2 Se 3 surface and Ti states (see Appendix A). Therefore, we can judiciously assume that the effect of the leads is essentially to broaden the discrete Fabry-Perot resonances in the confined central region.…”

Revealing the Substrate Dependent Ultrafast Phonon Dynamics in Bi2Se3 Thin Films

“…The Bi 2 Se 3 has additional bulk conduction band energy levels above this level. [39][40][41][42][43] Thus, GSB is caused by the metastable state in the second bulk conduction band of bismuth selenide. [4,9] Both the GSB and ESA have maxima at 2 ps, after which they begin to decrease.…”

Amorphous Bi$_2$Se$_3$ structural, electronic, and topological nature by first-principles

“…Layered Bi and Sb chalcogenides have been extensively studied due to their enhanced thermoelectric properties [16][17][18][19][20]. Several works have demonstrates a variety of interesting electronic properties of the topological phases in these materials: doping to control of the electronic structure and surface states [21][22][23][24]; alloying induced topological phase transition [25]; temperature effects in the electronic structure and temperature-induced phase transition [26,27]; spinpolarized transport and spin-orbit torque [28][29][30]; and unique properties of heterostructures [31][32][33][34][35]. Additionally, compounds belonging to the class of chalcogenides alloys are candidates for optical data storage, and electronic phase change memories due to a fast transition between crystalline and amorphous phases [36,37].…”