Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 7: "New" Materials and New Physics in "Old" Materials I

HL 7.7: Vortrag

Montag, 26. März 2012, 11:00–11:15, EW 015

Electronic and vibrational properties of single- and few-layer MoS₂ — •Gerd Plechinger, Stefanie Heydrich, Johannes Schmutzler, Franz-Xaver Schrettenbrunner, Jonathan Eroms, Dieter Weiss, Christian Schüller, and Tobias Korn — Institut für experimentelle und angewandte Physik, Universität Regensburg, 93040 Regensburg, Germany

The layered transition-metal dichalcogenide MoS₂ has attracted great interest because of good optical properties and as alternative to graphene for nanoelectronic applications. With the transparent tape liftoff method, single- and few-layer MoS₂ flakes were prepared. By annealing the samples in vacuum, photoluminescence peak intensity positions varying by about 20 meV at room temperature, were made uniform. Low temperature photoluminescence measurements on single-layer MoS₂ flakes show an additional low-energy peak. It can be attributed to a surface-bound exciton, because samples with a HfO₂ or Al₂O₃ coating do not show the low-energy peak.

In Raman-measurements, we have identified an interlayer shear mode at 30 cm⁻¹ in bulk material. We observed a decrease in wavenumber with decreasing layer number. By scanning an area on the sample, we can distinguish regions of different layer numbers by mapping the spectral position of the shear mode.