GeP3: A small indirect band gap 2D crystal with high carrier mobility and strong interlayer quantum confinement

TL;DR

This paper introduces GeP3, a 2D material with low indirect band gaps, high carrier mobility, and tunable electronic properties, suitable for optoelectronic applications like photovoltaics.

Contribution

It reports the discovery of a stable 2D GeP3 crystal with unique quantum confinement effects and strain-tunable band gaps, expanding the family of 2D materials.

Findings

GeP3 has a monolayer band gap of 0.55 eV and bilayer of 0.43 eV.

Strong interlayer quantum confinement causes a transition from semiconductor to metal.

Pronounced light absorption suggests potential in photovoltaic devices.

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. It has a small cleavage energy, 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.