Physics and controllability of phase transitions in two-dimensional materials  (Conference Presentation)

Ying Wang; Xiang Zhang

doi:10.1117/12.2320640

17 September 2018 Physics and controllability of phase transitions in two-dimensional materials (Conference Presentation)

Ying Wang, Xiang Zhang

Author Affiliations +

Proceedings Volume 10721, Active Photonic Platforms X; 1072124 (2018) https://doi.org/10.1117/12.2320640
Event: SPIE Nanoscience + Engineering, 2018, San Diego, California, United States

Abstract

2D materials capable of altering innate optical properties are highly demanded with broad photonic and optoelectronic applications, especially for ultrathin and ultracompact optical devices.We first demonstrated electrostatic doping driven structural phase transition in monolayer molybdenum ditelluride (MoTe2). The reversible structural phase transition between the hexagonal and monoclinic phases is directly controlled by electrostatic gating and verified through non-polar and polarized Raman spectra. An interesting hysteresis behavior has been observed in Raman and Second Harmonic Generation (SHG). And crystal orientation during phase change is found to be conserved, making such transition robust. We also discover out-of-plane 2D ferroelectricity in atomically thin In2Se3 crystal. Through Piezoresponse Force Microscopy (PFM) and SHG, we experimentally found that in-plane lattice asymmetry and out-of-plane polarization is dynamically locked during phase change. Such unique locking mechanism stabilizes the polar order and enables a robust 2D ferroelectricity at ambient conditions with a high transition temperature. The discovery is important to the atomically thin sensors and ultrahigh density nonvolatile memory devices.

Conference Presentation

Citation Download Citation

Ying Wang and Xiang Zhang "Physics and controllability of phase transitions in two-dimensional materials (Conference Presentation)", Proc. SPIE 10721, Active Photonic Platforms X, 1072124 (17 September 2018); https://doi.org/10.1117/12.2320640

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