Atomic mechanism of the semiconducting-to-metallic phase transition in single-layered MoS2

Abstract

Phase transitions can be used to alter the properties of a material without adding any additional atoms and are therefore of significant technological value. In a solid, phase transitions involve collective atomic displacements, but such atomic processes have so far only been investigated using macroscopic approaches. Here, we show that in situ scanning transmission electron microscopy can be used to follow the structural transformation between semiconducting (2H) and metallic (1T) phases in single-layered MoS2, with atomic resolution. The 2H/1T phase transition involves gliding atomic planes of sulphur and/or molybdenum and requires an intermediate phase (α-phase) as a precursor. The migration of two kinds of boundaries (β- and γ-boundaries) is also found to be responsible for the growth of the second phase. Furthermore, we show that areas of the 1T phase can be controllably grown in a layer of the 2H phase using an electron beam.

Graphene versus MoS2: A short review

“…While the studies on the yield stress in SLMoS 2 are limited, the novel structure transition in SLMoS 2 has received considerable attention [70][71][72][73]. In this structure transition, the outer two S atomic layers are shifted relative to each other, leading to abrupt changes in the electronic and phonon properties in SLMoS 2 .…”

Ternary CuIn7Se11: Towards Ultra‐Thin Layered Photodetectors and Photovoltaic Devices

“…Previous studies have shown, however, that elemental composition plays an important role in defining the physical properties of 2D materials. For example, binary systems and their alloys exhibit a variety of behaviors and modification spaces that can be optimized to meet the requirements of applications: the 1T-2H phase transition in transition metal dichalcogenides, [24][25][26][27] similar phase transitions in InSe, [28] and the structure of junctions between MoS 2 and WS 2 , [29] are but a few examples. In sharp contrast, modification methods for the properties of single elemental systems are far more limited.…”

Metallic and highly conducting two-dimensional atomic arrays of sulfur enabled by molybdenum disulfide nanotemplate

“…13 In addition, experimentally and computationally it has demonstrated that external high pressure (~19 to 40 GPa) could induce the semiconducting to metallic transition.…”