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We present experimental results revealing new details of the resonant electromagnetic behavior of a single TiO2 microsphere in the THz frequency range. In order to reduce background signal contributions and to increase the excitation efficiency, measurements are done using aperture-less photoconductive near-field microprobes in parallel and crossed alignment to the polarization of a free-space radiation...
Planar resonator arrays are becoming increasingly important for THz sensing applications. Minute amounts of sample substances placed at the array surface can be detected with orders of magnitude enhanced sensitivity compared to pure transmission because of resonator-induced local field enhancement. However, for further optimization of sensitivity and read-out speeds as well as advanced scientific...
Terahertz (THz) near-field microscopy is presented as a new characterization tool for photovoltaic applications: High-resolution sheet resistance measurements at interdigitated back-contact (IBC) solar cell samples are conducted, revealing previously undetectable features with lateral dimensions as small as a few tens of μm. Despite the very high maximum resolution the method is reasonably fast and...
A novel THz emitter and transceiver for on-chip failure location and waveguide inspection is introduced. Based on a flexible PET cantilever it features a CPS waveguide for wear-free capacitive coupling to devices under test (DUTs). Embedded LT-GaAs photoconductive switches allow for ultra-high bandwidth THz pulse generation and detection which is demonstrated in exemplary measurements on CPS structures...
Doping layers like the emitter or a surface field in silicon solar cells have to fulfill two important functions: They have to allow ohmic contact formation and they should also suppress Auger and surface recombination effects. The latter can be supported by an electrical field, provided by the layer itself. In the case of an emitter this is provided by a peak doping concentration beneath the surface,...
Photoconductive Terahertz microprobes have been crystalized as powerful measurement tools for high-resolution conductivity imaging, chip inspection and near-field imaging applications. In this work we demonstrate their integration into a high-speed system with 250 pixels/s data acquisition rate.
In this work a compact microprobe for advanced chip-inspection applications is introduced. The probe features integrated photoconductive switches for Terahertz pulse generation and detection. Device application is demonstrated for contact-free high-resolution time-domain reflectometry measurements at silicon-chip test structures.
We present THz emission based on phase-matched difference frequency generation from ultra-short laser pulses with λ = 1560 nm in a plasma-activated silicon nanophotonic waveguide with second-order nonlinearity. Phase-matching is achieved using a hybrid-approach with coplanar transmission lines.
Recently, the interest in silicon-based nanophotonic devices with electro-optic functionality has strongly increased. In Silicon a second-order electro-optic activity can be induced by breaking the inversion symmetry of the crystal lattice. Commonly this is done by straining the silicon lattice for example by applying a SiliconNitride layer to a nanophotonic waveguide [1,2]. Another innovative approach...
Recently, the demand for non-destructive contact-free measurement tools which are able to measure conductivity distributions at spatial resolutions down to a few micrometres has strongly increased. This demand is caused by an increased application of micron-scale doping areas in solar cells (e.g. selective emitter structures fabricated by laser-doping [1]) and further semiconductor applications. Although,...
Integrated THz pulse generation and amplification in THz QCLs is demonstrated. Intracavity narrowband THz pulses are generated at 2.1THz by exciting the facet of a THz quantum cascade laser with a resonant interband-intersubband transition and detected using electro-optic sampling.
Terahertz pulse generation is demonstrated by a resonant femtosecond interband excitation of the miniband of a quantum-cascade-laser. The laser gain is subsequently used to amplify the terahertz pulse generated as it propagates through the cavity.
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