Anisotropic Bi2O2Se(Te) Monolayer: Realizing Ultra-High Carrier Mobility and Giant Electric Polarization in Two-Dimension

TL;DR

This study identifies Bi2O2Se and Bi2O2Te monolayers as promising two-dimensional materials with ultra-high carrier mobility, giant electric polarization, and strong optical absorption, suitable for advanced electronic and optoelectronic applications.

Contribution

The paper predicts and characterizes the structure, high mobility, and polarization properties of Bi2O2Se(Te) monolayers, revealing their potential in electronic and photovoltaic devices.

Findings

Bi2O2Se monolayer has ultra-high carrier mobility.

Bi2O2Te monolayer exhibits electron mobility up to 3610 cm2V-1s-1.

Both materials show strong electric polarization and piezoelectricity.

Abstract

Here, we have identified the monolayer phase of Bi2O2Se as a promising two-dimensional semiconductor with ultra-high carrier mobility and giant electric polarization. Due to the strong reconstruction originated from the interlayer electrostatic force, we have applied structure prediction algorithms to explore the crystalline geometry of Bi2O2Se monolayer with the lowest total energy. Considering Se and Te belong to the same group, Bi2O2Te monolayer is also investigated based on a similar scheme. Further calculations suggest that the high carrier mobility is maintained in the monolayer phase and the moderate band gap will lead to the strong optical absorption in the visible light region. In particular, the electron mobility in Bi2O2Te can reach as high as 3610 cm2V-1s-1 at room temperature, which is almost ten times of conventional transition metal dichalcogenides (TMD) family. Because of the strong structural anisotropy, a remarkable spontaneous in-plane and out-of-plane electric polarization is additionally revealed along with significant piezoelectric properties, endowing them as promising candidates in the area of photovoltaic solar cells, optoelectronic materials and field effect transistors.