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Semiconductor-metal structural phase transformation in MoTe2 monolayers by electronic excitation
Aravind Krishnamoorthy1, Lindsay Bassman Oftelie, Rajiv K Kalia
1Collaboratory for Advanced Computing and Simulations, University of Southern California, Los Angeles, CA 90089, USA. kris658@usc.edu.
Nanoscale
|January 16, 2018
Summary
Optical excitation can control crystal structure transformations in two-dimensional semiconductors like molybdenum ditelluride (MoTe2). This enables new pathways for creating advanced nano-electronics by forming semiconductor-metal heterophase homojunctions.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Optical modulation is key for functionalizing 2D semiconductors where doping is difficult.
- Controlling polytype transformations (semiconducting H to semimetallic T') in transition metal chalcogenides is vital for 2D electronics.
- Optical excitation-driven phase transformations and their mechanisms remain underexplored.
Purpose of the Study:
- To model the excited state of MoTe2 crystals.
- To investigate the mechanism of optical excitation-induced semiconductor-metal phase transformation.
- To explore the potential for creating heterophase homojunctions in 2D materials.
Main Methods:
- Modeling of electronic and ionic structure in excited MoTe2.
- Analysis of phonon mode softening driven by Fermi-surface nesting.
- Investigation of potential energy surfaces and activation barriers for phase transitions.
Main Results:
- Electronic excitation softens phonon modes at the Brillouin zone boundary.
- A low-energy intermediate crystal structure is stabilized along the semiconductor-metal transition pathway.
- Reduced activation barriers for transformation under electronic excitation were observed.
Conclusions:
- Optical excitation can drive semiconductor-metal phase transitions in MoTe2.
- This mechanism offers a route for rapid, controllable synthesis of lateral heterophase homojunctions.
- Potential applications lie in next-generation 2D nano-electronics.
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