This atomic force microscopy system (FlexAFM from NanoSurf) with lock-in capability allows the simultaneous imaging of the surface topography and the spatial mapping of surface acoustic waves in the GHz frequency and submicron wavelength range. In addition to the topography modes, it is also capable of performing magnetic force microscopy.
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We operate three optical spectroscopy setups to study the optoelectronic properties of semiconductor nanostructures in the presence of dynamic acoustic fields. All setups include cryostats with optical access and radio frequency ports for excitation of acoustic resonators and monochromators for spectroscopic analysis. They are optimized for the study of various optical properties in the near-infrared spectral range.
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Cathodoluminescence (CL) spectroscopy and imaging can be performed using a field-emission scanning electron microscope (FE-SEM) with a spatial resolution down to the nanometer range. In semiconductors, the incident electron beam in an SEM excites carriers from the valence to the conduction band. The subsequent relaxation of carriers results in light emission, which can then be analyzed by the spectrometer.
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For spatially resolved µ-Raman- and photoluminescence spectroscopy, two commercial setups are available, namely, a Jobin-Yvon Horiba LabRAM HR Evolution and a Renishaw inVia Raman microscope. Both instruments utilize single spectrometers and edge/notch filters for stray light suppression, as well as confocal microscopes for excitation and detection. They combine high spectral resolution, high optical throughput, and ease of use.
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For the characterization of electrical transport properties, two custom built setups are available, namely a system for Hall effect measurements and a mechanical probe station with a semiconductor analyzer as well as a Seebeck module.
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Electrical and spectroscopic characterization of the lasing parameters of quantum-cascade lasers (QCLs) in the far-infrared or terahertz spectral region.
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For various types of measurements utilizing Raman, photoluminescence (PL) and - in particular - PL excitation (PLE) spectroscopy, a custom built setup is available.
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The AttoLiquid1000 (Attocube Systems) cryostat in this lab comprises a superconducting vector magnet and can be used for combined atomic force and confocal optical microscopy by utilizing an attoAFM/CFM insert.
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Electronic quantum properties of semiconductor-based artificial mesoscopic or nanoscale structures are explored using cryogenic transport measurements to provide a scientific background for future quantum technology applications.
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The characterization of acoustic delay lines and resonators for surface and bulk acoustic waves patterned in semiconductor substrates up to 100 mm in diameter is performed in mechanical probe stations. These are equipped with microscopes and radio frequency probes connected to the ports of a vector network analyzer.
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