Abstract
The interesting and tunable properties of layered metal dichalcogenides heavily depend on their phase and layer stacking. Here, we show and explain how the layer stacking and physical properties of WSe2 are influenced by screw dislocations. A one-to-one correlation of atomic force microscopy and high- and low-frequency Raman spectroscopy of many dislocated WSe2 nanoplates reveals variations in the number and shapes of dislocation spirals and different layer stackings that are determined by the number, rotation, and location of the dislocations. Plates with triangular dislocation spirals form noncentrosymmetric stacking that gives rise to strong second-harmonic generation and enhanced photoluminescence, plates with hexagonal dislocation spirals form the bulk 2H layer stacking commonly observed, and plates containing mixed dislocation shapes have intermediate noncentrosymmetric stackings with mixed properties. Multiple dislocation cores and other complexities can lead to more complex stackings and properties. These previously unobserved properties and layer stackings in WSe2 will be interesting for spintronics and valleytronics.
| Original language | English |
|---|---|
| Pages (from-to) | 3496-3504 |
| Number of pages | 9 |
| Journal | Journal of the American Chemical Society |
| Volume | 139 |
| Issue number | 9 |
| DOIs | |
| State | Published - Mar 8 2017 |
Funding
This research is supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under Award DE-FG02-09ER46664. M.J.S. and L.S. also thank the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE-1256259 for support. Support was also provided by the Graduate School and the Office of the Vice Chancellor for Research and Graduate Education at the University of Wisconsin−Madison with funding from the Wisconsin Alumni Research Foundation. The authors also thank Professor Bruce Parkinson for supplying the 2H-WSe2 single crystal. The low-frequency Raman spectroscopy was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. M.J.S. would like to thank Dr. David Gosztola for helping with the photoluminescence and absorbance measurements performed at the Center for Nanoscale Materials at Argonne National Laboratory, which is supported by the U.S Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. M.J.S. and L.S. would like to thank Dr. Josh Weber for his help conducting the second harmonic generation measurements, performed at the Laboratory for Optical and Computational Instrumentation at UW−Madison.
| Funders | Funder number |
|---|---|
| National Science Foundation | DGE-1256259 |
| U.S. Department of Energy | DE-AC02-06CH11357 |
| Wisconsin Alumni Research Foundation | |
| Office of Science | |
| Basic Energy Sciences | |
| Argonne National Laboratory | |
| Office of the Vice Chancellor for Research and Graduate Education, University of Wisconsin-Madison | |
| Division of Materials Sciences and Engineering | DE-FG02-09ER46664 |
| Graduate School, University of Oregon |