Dr. Jun Xiao received a Ph.D. degree in Applied Physics from UC Berkeley (2018) and a B.S. degree in Physics from Nanjing University (2012).
Jun’s research has centered on the exploration of the emerging properties of two-dimensional materials through the application of a wide range of optical spectroscopy, scanning probe microscopy and electrical measurements. More specifically, he conducted experimental investigation in how crystal symmetry and symmetry breaking substantially influence on optoelectronic properties, polar structures and phase transitions in two-dimensional systems. Along this line, Jun is also interested in visualizing the ultrafast dynamics and driving nonequilibrium phase transition in quantum materials.
Dr. Jun Xiao has published over 10 high-impact journal papers including publications in Science, Nature, Nature Nanotechnology, Physical Review Letters and Nature Communications.
Doctor of Philosophy, University of California Berkeley (2018)
Structural phase transition in monolayer MoTe2 driven by electrostatic doping
2017; 550 (7677): 487-+
Monolayers of transition-metal dichalcogenides (TMDs) exhibit numerous crystal phases with distinct structures, symmetries and physical properties. Exploring the physics of transitions between these different structural phases in two dimensions may provide a means of switching material properties, with implications for potential applications. Structural phase transitions in TMDs have so far been induced by thermal or chemical means; purely electrostatic control over crystal phases through electrostatic doping was recently proposed as a theoretical possibility, but has not yet been realized. Here we report the experimental demonstration of an electrostatic-doping-driven phase transition between the hexagonal and monoclinic phases of monolayer molybdenum ditelluride (MoTe2). We find that the phase transition shows a hysteretic loop in Raman spectra, and can be reversed by increasing or decreasing the gate voltage. We also combine second-harmonic generation spectroscopy with polarization-resolved Raman spectroscopy to show that the induced monoclinic phase preserves the crystal orientation of the original hexagonal phase. Moreover, this structural phase transition occurs simultaneously across the whole sample. This electrostatic-doping control of structural phase transition opens up new possibilities for developing phase-change devices based on atomically thin membranes.
View details for PubMedID 29019982