Phase Transformation-Induced Quantum Dot States on the Bi/Si(111) Surface

Abstract

Nanopatterns at near atomic dimensions with controllable quantum dot states (QDSs) are promising candidates for the continued downscaling of electronic devices. Herein, we report a phase transition-induced QD system achieved on the √3 × √3-Bi/Si(111) surface reconstruction, which points the way to a novel strategy on QDS implementation. Combining scanning tunneling microscopy, scanning tunneling spectroscopy, and density functional theory (DFT) calculations, the structure, energy dispersion, and size effect on band gap of the QDs are measured and verified. As-created QDs can be manipulated with a dot size down to 2 nm via Bi phase transformation, which, in turn, is triggered by thermal annealing at 700 K. The transition mechanism is also supported by our DFT calculations, and an empirical analytical model is developed to predict the transformation kinetics.

Emergence of quasi-1D spin-polarized states in ultrathin Bi films on InAs(111)A for spintronics applications

“…22 Almost any 2D material except graphene requires an appropriate supporting substrate, which either provides a charge transfer resulting in the doping of electrons or holes to the adsorption layer in the case of a weakly coupled interface 23 or modulates the structure of the epitaxial layer in the case of a strongly coupled interface. 24,25 The synthesis of low-dimensional Bi-induced phases on semiconducting interfaces is a hot topic; however, α(β)-Bi/Si(111) phases demonstrate significant band gaps and zero density of states in the electronic spectrum, [26][27][28] which hinders their prospects for spintronics applications; the same status is observed with Bi films on Ge (111), 29,30 where surface spin-split bands are merged within the bulk state area.…”