$\mathrm{Tl}{\mathrm{P}}_5$: An unexplored direct band gap 2D semiconductor with ultra-high carrier mobility

Abstract

Two-dimensional materials with a proper band gap and high carrier mobility are urgently desired in the field of nanoelectronics. We propose a novel two-dimensional crystal monolayer $\mathrm{Tl}{\mathrm{P}}_5$, which is dynamically and thermodynamically stable and possesses a direct band gap of 2.02 eV with high carrier mobilities (13960 $\mathrm{c}{\mathrm{m}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ for electrons and 7560 $\mathrm{c}{\mathrm{m}}^2{\mathrm{V}}^{-1}{\mathrm{s}}^{-1}$ for holes), comparable to that of phosphorene. The band gap value and band characteristics of monolayer $\mathrm{Tl}{\mathrm{P}}_5$ can be adjusted by biaxial and uniaxial strains, and excellent optical absorption over the visible-light range is predicted. These properties, especially for the balanced high mobilities for not only the electrons but also the holes, render monolayer $\mathrm{Tl}{\mathrm{P}}_5$ an exciting functional material for future nanoelectronics and optoelectronic applications.

5 figures, 1 table