Abstract
A newC2hphase of 2D group III monochalcogenides with excellent electronic properties is computationally predicted and explored.
Highlights
Two-dimensional (2D) group III monochalcogenides (MX, M = Ga, In and X = S, Se, Te) are promising candidates for next-generation ultrathin optoelectronic devices due to their exotic properties
We further explore the polymorphic nature of 2D MX semiconductors through artificial swarm intelligence computational structural searches on CALYPSO (Crystal structure AnaLYsis by Particle Swarm Optimization)[36] and ab initio calculations using the Vienna ab initio simulation package (VASP) software,[37,38,39,40] and identified a monolayer phase belonging to the C2h point group
Ab initio molecular dynamics (AIMD) calculations were performed through the Vienna ab initio simulation package (VASP) software[37,38,39,40] using the NVT ensemble in which the temperature was held constant at 300 K in the Nose–Hoover thermostats.[41]
Summary
New polymorphs of 2D MXs belonging to the space group C2h are predicted through a global structural search based on artificial swarm intelligence and density functional theory calculations We demonstrate that such monolayer polymorphs are thermodynamically and kinetically stable through phonon spectrum analysis and ab initio molecular dynamics simulations. Examples include the coexistence of metallic octahedral (1T0) and semiconducting trigonal prismatic (2H) monolayer MoS223,24 as well as the presence of blue phosphorus with wider band gaps compared to the black phosphorus polymorphs.[25] the exploration of monolayer polymorphs of known semiconductors leave room for the discovery of unexpected properties and emergent applications Among these 2D materials, group III monochalcogenides (MX), represented by InSe, have attracted growing research attention because of their idiosyncratic optoelectronic properties and their promising potential applications as field-effect transistors,[17,21] photodetectors,[26,27,28] and photocatalysts.[30] Significant efforts have been spent on investigating the polymorphic nature of MXs. Take InSe as an example. Such superior properties render the C2h III–VI binary 2D semiconductors worthwhile for further studies to shape them into promising candidates for high-performance electronics and optoelectronics
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