Abstract
In this paper, we investigated the electronic and optical properties of silicene on GaAs(111) substrates (silicene/HGaAs) on the basis of first-principles density functional theory. The hydrogen intercalation introduced substantially weakened the interaction between silicene and the GaAs(111) substrate and induced considerable bandgaps in silicene/HGaAs heterostructures. The effects of the interlayer spacing (L) between silicene and the substrate, silicene buckling height (h), biaxial strain (ε), and external electric field (F) on the electronic properties were also considered. Our results showed that the electronic properties of silicene/HGaAs heterostructures could be controlled by adjusting L and h and applying ε and an external F. Silicene/HGaAs heterostructures possessed the typical optical absorption properties of freestanding silicene and had high absorption coefficients. Besides, some strong peaks of absorption spectra and energy loss spectra existed in the ultraviolet light region, which showed that silicene/HGaAs heterostructures had evident enhancement in the ultraviolet light region. Results laid a theoretical foundation for the study of the electronic and optical properties and applications of silicene on semiconductor substrate devices.
Highlights
Low-dimensional materials are important for the development of modern industry nowadays due to the demand for miniature electronic devices.[1,2,3] Two-dimensional layered materials have high mechanical toughness, adjustable bandgap energy (Eg) and optical transparency, and a high surface area ratio.[4]
Where EHGaAs, Esilicene, and Etot are the energies of the GaAs(111) substrate with hydrogen intercalation, isolated silicene, and silicene/HGaAs heterostructure, respectively, and N is the number of Si atoms in the silicene layer
The existence of the direct bandgap indicates that the interaction between the silicene layer and the As-terminated GaAs(111) surface is largely weakened by the hydrogen intercalation, resulting in no electronic orbital hybridization between Si atoms in the silicene layer and the substrate surface
Summary
Low-dimensional materials are important for the development of modern industry nowadays due to the demand for miniature electronic devices.[1,2,3] Two-dimensional layered materials have high mechanical toughness, adjustable bandgap energy (Eg) and optical transparency, and a high surface area ratio.[4]. The buckled two-dimensional silicon is foreseen two decades ago (prior to graphene),[8] and silicene was successfully grown on Ag(111) single crystals in 20129–11 and the properties on this substrate were fully studied.[12,13,14] The freestanding silicene layer is extremely unstable under normal temperature and pressure and is oxidized, thereby losing its structural characteristics when exposed to air.[15] This surface sensitivity comes from its mixed sp2–sp[3] characteristics.[16] Its instability in the air has severely limited investigations of its experimental properties. The effects of interlayer spacing (L) between silicene and the substrate, buckling height (h), biaxial strain (3), and external electric eld (F) on its electronic properties are considered It provides theoretical supports for the growth of silicene on semiconductor substrates and the application of silicene devices in experiments
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