Structural evolution and optoelectronic applications of multilayer silicene

Abstract

Despite the recent progress on two-dimensional multilayer materials (2DMM) with weak interlayer interactions, the investigation on 2DMM with strong interlayer interactions is far from its sufficiency. Here we report on first-principles calculations that clarify the structural evolution and optoelectronic properties of such a 2DMM, multilayer silicene. With our newly developed global optimization algorithm, we discover the existence of rich dynamically stable multilayer silicene phases, the stability of which is closely related to the extent of sp 3 hybridization that can be evaluated by the average bonds and effective bond angles. The stable Si(111) surface structures are obtained when the silicene thickness gets up to four, showing the critical thickness for the structural evolution. We also find that the multilayer silicene with π-bonded surfaces present outstanding optoelectronic properties for the solar cells and optical fiber communications due to the incorporation of sp 2 -type bonds in the sp 3 -type bonds dominated system. This study is helpful to complete the picture of structure and related property evolution of 2DMM with strong interlayer interactions.

Prediction of two‐dimensional materials by the global optimization approach

“…54 silicene from the monolayer to quadlayer. 113 The most stable bilayer silicene phase is the same as that obtained in previous work. 54,122 For trilayer silicene, the two most stable present a 2 × 1 periodicity with hexagonal and rectangular supercells, which have P121/m1 and P1 symmetries, respectively.…”

“…Instead, Luo et al found a new bilayer structure which has a lower total energy than that of AA‐Si by 41 meV/atom . Afterwards, Guo et al performed extensive searches for the most stable phases of silicene from the monolayer to quadlayer . The most stable bilayer silicene phase is the same as that obtained in previous work .…”

Quantum Simulation of Single-Qubit Thermometry Using Linear Optics

“…These considerations find an immediate application in the context of thermometry, since, on the one hand, we assist at the interaction for a given time of a probe with the monitored system, while, on the other, the probe itself needs being prepared in an informative, hence resourceful, state [13][14][15][16][17]. In [18], Jevtic et al have discussed the implementation of an elementary thermometer with a single qubit: the task is not the estimation of arbitrary temperatures, but the discrimination between two thermal baths at different temperatures.…”

A new series of two-dimensional silicon crystals with versatile electronic properties

“…In addition, due to the strong covalent bonding character of Si, as-cleaved surfaces inevitably have unpaired electrons localized at dangling bonds on the surface, which makes an energetically unfavorable situation. This is evidenced by prevalent severe surface reconstruction to reduce the number of unpaired electrons as can be seen in most of the previously reported 2D Si crystals [21][22][23][24][25][26][27]33 . In all the cases, however, some of the surface atoms still remain under-coordinated even after the reconstruction, implying that those atoms prone to form strong covalent bonding with one another as pointed out in the case of silicene 1,37 .…”

“…1. The surface layer features perfectly planar stable hexagonal framework unlike other 2D Si crystals that have hitherto been studied [21][22][23][24][25][26][27][28][29][30][31][32][33] , in which buckled surfaces are predominant. Moreover, the crystal is completely free from coordination number (CN) defects.…”