GeP₃: A Small Indirect Band Gap 2D Crystal with High Carrier Mobility and Strong Interlayer Quantum Confinement

Abstract

We propose a two-dimensional crystal which possesses low indirect band gaps of 0.55 eV (monolayer) and 0.43 eV (bilayer) and high carrier mobilities similar to those of phosphorene: GeP3. GeP3 has a stable three-dimensional layered bulk counterpart which is metallic and is known from experiment since 1970. GeP3 monolayer has a calculated cleavage energy of 1.14 J m -2 , which suggests exfoliation of bulk material as viable means for the preparation of mono-and few-layer materials. The material shows strong interlayer quantum confinement effects, resulting in a band gap reduction from mono-to bilayer, and then to a semiconductor-metal transition between bi-and triple layer. Under biaxial strain, the indirect band gap can be turned into a direct one. Pronounced light absorption in the spectral range from ~600 to 1400 nm is predicted for monolayer and bilayer and promises applications in photovoltaics.

Effects of the number of layers on the vibrational, electronic and optical properties of alpha lead oxide

“…The highest optical frequency modes of monolayer PbO reach 13.91 Thz. This vibration mode value is very close to that of MoS 2 (14.18 THz), 39 indicating the robustness of the covalent oxygen-oxygen bonds between the lead atoms. On the other hand, vibrational modes of lead atoms are under of 4.2 THz.…”

BaAs3: a narrow gap 2D semiconductor with vacancy-induced semiconductor–metal transition from first principles

“…2c. The DFT-estimated exfoliation energy of ML BaAs3 is larger than that of graphite (0.37 J m -2 from experimental and 0.32 J m -2 in theory) [41,42] but at the same level of InP3 (1.32 J m -2 ) [14], GeP3 (1.14 J m -2 ) [15], CaP3 (1.30 J m -2 ) [18] and CaAs3(1.36 J m -2 ) [19]. Therefore, in principle ML BaAs3 crystal could be prepared experimentally from its bulk counterpart using mechanical cleavage or liquid phase exfoliation.…”

“…Very recently, a series of 2D pnictides (nitrides, phosphides and arsenides) semiconductors have been theoretically proposed as novel 2D semiconductors with high carrier mobilities (~10 3 cm 2 V -1 s -1 -10 5 cm 2 V -1 s -1 ) that are comparable or superior to those of phosphorene [14][15][16][17][18][19][20][21][22][23][24][25]. For instance, in monolayer Pt2N4 with a planar pentastructure, the electron mobility at room temperature can reach 1.1×10 5 cm 2 V -1 s -1 , comparable to that in graphene [20].…”

2D GeP as a Novel Broadband Nonlinear Optical Material for Ultrafast Photonics

“…In regard to 2D Ge–P compounds, including GeP, GeP 2 , GeP 3 , and GeP 5 , some significant investigations have been performed. The calculation shows that GeP 3 possesses a higher chemical stability than BP, a high carrier mobility (8.84 × 10 3 cm 2 V −1 s −1 ), a moderate tunable E g from 0 to 0.55 eV and pronounced light absorption in the spectral range from ≈600 to 1400 nm, which indicates that GeP 3 is a promising candidate for optoelectronic and photonic application. However, much of the research on 2D Group IV–P focuses on theory, whereas experimental exploration is extremely rare.…”