Exceptional Optoelectronic Properties of Hydrogenated Bilayer Silicene

Abstract

Silicon is arguably the best electronic material, but it is not a good optoelectronic material. By employing first-principles calculations and the cluster-expansion approach, we discover that hydrogenated bilayer silicene (BS) shows promising potential as a new kind of optoelectronic material. Most significantly, hydrogenation converts the intrinsic BS, a strongly indirect semiconductor, into a direct-gap semiconductor with a widely tunable band gap. At low hydrogen concentrations, four ground states of single-and doublesided hydrogenated BS are characterized by dipole-allowed direct (or quasidirect) band gaps in the desirable range from 1 to 1.5 eV, suitable for solar applications. At high hydrogen concentrations, three well-ordered double-sided hydrogenated BS structures exhibit direct (or quasidirect) band gaps in the color range of red, green, and blue, affording white light-emitting diodes. Our findings open opportunities to search for new silicon-based light-absorption and light-emitting materials for earth-abundant, highefficiency, optoelectronic applications.

Prediction of Silicon-Based Layered Structures for Optoelectronic Applications

“…energy by 73 meV/atom than the previous proposed structure. 39 shows that the band edge states, in particular the CBM state, distribute mostly around the Si triangle. The computed imaginary part ε 2 of the dielectric function shows that direct-gap transition in Si 6 H 2 -Pmm2 is dipole allowed (see figure 6).…”

“…20 For bi-layer Si, it is widely accepted the AA stacking configuration [shown in figure 1(b), referred as AA-Si) is the most stable structure. 39 Recently, Florian…”

Free-Standing Bilayer Silicene: The Effect of Stacking Order on the Structural, Electronic, and Transport Properties

“…13,18 Kawai et al 19 presented a well succeeded synthesis of a bilayer silicene on a (111) Ag surface. [31][32][33][34] Thus, a comprehensive study of the electronic and transport properties of the free-standing bilayer silicene as function of the stacking order is still lacking. [20][21][22][23][24][25][26][27][28][29][30] However, only few theoretical investigations have dealt with the bilayer silicene.…”

First‐principle calculations of optical properties of monolayer arsenene and antimonene allotropes

“…Graphene is a honeycomb monolayer of carbon atoms, which possesses superior carrier mobility 4 , but with a small on-off ratio due to the zero band gap, which limits the applications in electronic devices. Black phosphorene [5][6][7] , a monolayer of phosphorus atoms with puckered structure, induces great attention recently due to the versatile properties such as direct semiconducting property with a moderate band gap 8 , a higher hole mobility comparable to graphene 9 , high carrier mobility 10 , strongly anisotropic transport 5 and etc.…”