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Hybrid nanophotonic systems

Hybrid acousto-electric devices based on two-dimensional semiconductors

AES on MoS2We aim to combine surface acoustic wave devices and emerging optically active two-dimensional semiconductor materials such as MoS2 in novel acousto-electric and field-effect devices. SAWs are well suited to probe the conductivity of these ultimately thin semiconductors because no electrical contacts have to be fabricated. The figure compares the photoconductivity of MoS2 measure by a SAW (upper panel) or electrically (lower panel). The red laser generated charge carriers in the MoS2 layer, which leads to a pronounced chage of teh conductivity. The SAW response nicely reproduceds the directly measured trace. The infrared laser does not generate charge carriers and consequently no signal is detected.

In this project we collaborate with the group of Ludwig Bartels at the University of California at Riverside.

This work is supported by the Bavaria California research Center (BaCaTeC) , Deutsche Forschungsgemeinschaft via Research Grant KR3790/7-1 and the Nanosystems Initiative Munich (NIM).

Nanothermochromic diffraction gratings

Nanothermochromic_grating_diffractionOne example of a hybrid system studied in our group are nanothermochromic diffraction gratings fabricated by ion beam synthesis. These gratings contain VO2 nanoclusters which undergo a metal-insulator transition at TC=~68°C. At this critical temperature the refractive index of this material changes dramatically. This in turn gives rise to a giant change of the diffraction efficiency of the fabricated gratings. Two typical diffraction scans recorded at room temperature and at ~100°C are shown in the figure. For this experiment the wavelength of the diffracted light was 1550 nm. This wavelength is used for optical fiber communication and therefore technologically highly relevant .

In this project we closely collaborate with the group of Helmut Karl at the Chair Experimentalphysik IV.

This work is supported in parts Deutsche Forschungsgemeinschaft via the Emmy Noether Program (KR3790/2-1) and the Cluster of Excellence Nanosystems Initiative Munich.


Key publications:

Please see full publication list to find out more about our research activities.


Team:

Former PhD students

Former Master students

Former Bachelor students