Thermally Induced Defects on WSe2

• DOI: 10.1021/acs.jpcc.0c04440
• Publication Date: 2020-06-23T20:39:44Z
• Authors: William H. Blades; Nicholas J. Frady; Peter M. Litwin; Stephen J. McDonnell; Petra Reinke
• Keywords: Tungsten diselenide

The 2D nature of transition metal dichalcogenides (TMDs) makes their electronic and optical performance highly susceptible to the presence defects. At elevated temperatures, which can be reached during growth or in operation, additional defects introduced lead further material degradation. Therefore, by studying impact temperature on 2D-TMDs, formation respective degradation pathways established. geometric structure density thermally induced tungsten diselenide (WSe2) layers were examined using scanning tunneling microscopy/spectroscopy (STM/STS). WSe2 grown ordered pyrolytic graphite (HOPG), via molecular beam epitaxy (MBE) annealed at 600 °C, caused a 7-fold increase overall defect density. A layer-dependent trend emerged whereby first layer was greater than second, suggesting that TMD–graphite TMD–TMD van der Waals interactions influence energy inventory included single-point vacancies collection larger with complex signatures. These classified matching unique structures topographical presentation spatially resolved STS maps. Defect states conduction valence band edges n- p-type character generally lowered local gap around each site. displayed an increased gap, likely as consequence delamination TMD due subsurface Se–cluster formation. Density functional theory (DFT) used examine select supported interpretation STM/STS work (DOS) local-integrated DOS calculations. assessment signatures details doping profile all sites deepened our understanding thermal stability WSe2.