Band gap control and transformation of monolayer-MoS₂-based hetero-bilayers

Abstract

Study of heterostructured bilayer systems is an essential prerequisite for developing twodimensional nano-electronic devices. Using ab initio density functional theory calculations, we investigated the atomic and electronic properties of hetero-bilayers composed of silicene and germanene layers with monolayer MoS2. Our results show that both Silicene-MoS2 and Germanene-MoS2 hetero-bilayers are direct band gap semiconductors. The band gaps of silicene and germanene in hetero-bilayers are opened due to the sublattice symmetry breaking induced by the introduction of the MoS2 monolayer, indicating that the monolayer MoS2 makes a good complement to silicene and germanene. Moreover, tunable band gaps in silicene and germanene can be realized by changing the interlayer distance or employing inplane compressing/stretching. Especially, through compressing or stretching, the Germanene-MoS2 bilayers realize a transformation from an indirect band gap semiconductor to a direct band gap semiconductor, while the Silicene-MoS2 bilayers can keep the direct band gaps.Our results in this work provide a new way for designing applications in future MoS2-based nano devices with controllable band gaps.

Tunable Electronic Properties of Type-II SiS2/WSe2 Hetero-Bilayers

“…The lattice constants of SiS 2 and WSe 2 monolayers are calculated to be 3.30 and 3.33 Å, respectively, which agree well with previous results [ 33 , 41 , 42 ]. Compared with the hybrid systems investigated previously [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ], such a lattice mismatch (only about 0.9%) between the SiS 2 and WSe 2 monolayers is very small. Thus, we have employed supercells composed of 1 × 1 unit cells of SiS 2 monolayer and 1 × 1 unit cells of WSe 2 monolayer in the x-y plane.…”

“…Aretouli et al found that SnSe 2 /WSe 2 heterostructure possesses a broken gap configuration, indicating that band-to-band tunneling through an ultrathin van der Waals gap can be switched on and off easily via applying a small bias across the interface, which implies promising applications in 2D-2D vertical TFETs [ 29 ]. Thus, the heterostructures not only provide a new way to enrich the novel properties of the system but also to well preserve the electronic properties of the original freestanding two single-layer 2D components [ 30 , 31 , 32 ].…”

Excitonic quantum confinement modified optical conductivity of monolayer and few-layered MoS2

“…In recent years, two-dimensional (2D) transition metal dichalcogenide (TMDC) materials with the generalized formula MX 2 (M = Mo, W; X = S, Se, and Te) have received burgeoning research interest due to their peculiar physicochemical properties. [1][2][3][4][5] Their electronic states generally are subject to strong interlayer coupling and undergo transitions from the indirect bandgap in the bulk form to the direct bandgap in monolayers. In particular, the direct bandgap energy in many monolayer TMDCs lies in the visible and near infrared range, making them ideal candidates for 2D optoelectronic applications.…”

Construction of magnetic MgFe2O4/CdS/MoS2 ternary nanocomposite supported on NaY zeolite and highly efficient sonocatalytic degradation of organic pollutants

“…In the past few decades, molybdenum disulde (MoS 2 ) as an p-type semiconductor with a band gap energy approximately 1.9 eV (ref. 25 ) has been investigated as a suitable material owing to its unique properties like low toxicity, high catalytic performance, thermal and chemical stability, and high absorption capacity. In this regard, MoS 2 has been widely applied in multiple applications such as super capacitors, sensors, Li-ion batteries, photocatalysts and more.…”