Theoretical Study of Anisotropic Carrier Mobility for Two-Dimensional Nb₂Se₉ Material

Abstract

Finding new materials with satisfying all the desired criteria for nanodevices is an extremely difficult work. Here, we introduce a novel Nb 2 Se 9 material as a promising candidate, capable of overcoming some physical limitations, such as a suitable band gap, high carrier mobility, and chemical stability. Unlike graphene, it has a noticeable band gap and no dangling bonds at surfaces that deteriorate transport properties, owing to its molecular chain structure. Using density functional theory (DFT) calculations with deformation potential (DP) theory, we find that the electron mobility of 2D Nb 2 Se 9 across the axis direction reaches up to 2.56 × 10 3 cm 2 V −1 s −1 and is approximately 2.5−6 times higher than the mobility of other 2D materials, such as MoS 2 , black phosphorous, and InSe, at room temperature. Moreover, the mobility of 2D Nb 2 Se 9 is highly anisotropic (μ a /μ c ≈ 6.5). We demonstrate the potential of 2D Nb 2 Se 9 for applications in nanoscale electronic devices and, possibly, mid-infrared photodetectors.

Large and anisotropic carrier mobility in monolayers of the MA2Z4 series (M = Cr, Mo, W; A = Si, Ge; and Z = N, P)

“…We find that the monolayers considered in this work exhibit anisotropic carrier mobility, similar to that reported in other 2D materials such as phosphorene, PC 6 , group IVB dichalcogenide monolayers, etc. 26,[33][34][35][36][37][38][39][40][41] (see Table S4 in the ESI †). MoGe 2 P 4 is the most anisotropic monolayer, with the ratio of mobilities along the zigzag and armchair directions being ∼3.6.…”

Emerging quasi-one-dimensional material NbS4 with high carrier mobility and good visible-light adsorption performance for nanoscale applications

“…It can be found that the hole mobilities of the 1D NbS 4 nanowire is 316.63 cm 2 V À1 s À1 , which is larger than other 1D materials, such as Nb 2 Se 9 (2.5), 22 Ta 2 Ni 3 Se 8 (42.9), 23 X V Y VI Z VII (X = As, Sb, and Bi; Y = S, Se, and Te; Z = Cl, Br, and I) (ranging from 5.25 to 27.29), 27 InSeI (54.17), 96 Sn 2 S 3 (33.9) and Sn 2 Se 3 (309.1), 83 SbSeI (6.84) and SbSI (23.41) as well as SbSBr (0.64). 95 And the electron mobility of 1D NbS 4 nanowire is 111.9 cm 2 V À1 s À1 , which is larger than that of most reported 1D materials, such as Nb 2 Se 9 (41.9), 22 Ta 2 Ni 3 Se 8 (59.6), 23 most of X V Y VI Z VII (X = As, Sb, and Bi; Y = S, Se, and Te; Z = Cl, Br, and I) (ranging from 16.43 to 322.95), 27 Sn 2 S 3 (63.5), Sn 2 Se 3 (85.9), 83 SbSeI (25.69), SbSI (54.55), SbSBr (96.68), 95 and InSeI (27.49). 96 Furthermore, the carrier mobility of the 1D NbS 4 nanowire exhibits obvious anisotropy, manifesting that the hole mobility is approximately three times larger than the electron mobility.…”

“…For van der Waals materials, different band gap values and transport properties are common in the bulk phase and their isolated low-dimensional counterparts. The transformation of bandgap properties is also revealed with decreased dimension in the quasi-1D material Nb 2 Se 9 of the same family, 22,91 which is mainly attributed to the redistribution of electron density caused by the reduced dimensionality as well as the changed dispersion relationship. Moreover, the dimensionality reduction imposing quantum confinement on the electrons of the nanowires also plays a role in the indirect-todirect band gap transition from the bulk phase to a single nanowire.…”

“…20,21 Therefore, significant efforts have been devoted to exploring 2D materials with satisfactory properties including a finite band gap, high mobility, good stability, and the absence of surface dangling bonds, concomitant with quasi-2D conducting channels for future applications in nanoelectronics. 22 Moreover, along with the boom in the study of 2D nanowire materials 23 and the technological advances in nanotechnology devices, attention has shifted from 2D vdW layered materials to one-dimensional (1D) nanowires. 24 The reduction in the dimension of the 1D nanowire can further increase the surface area and flexibility compared to a 2D system.…”

“…20,21 Therefore, significant efforts have been devoted to exploring 2D materials with satisfactory properties including a finite band gap, high mobility, good stability, and the absence of surface dangling bonds, concomitant with quasi-2D conducting channels for future applications in nanoelectronics. 22…”