While nanophotonic devices are unfolding their potential for single-molecule fluorescence studies, metallic quenching and steric hindrance, occurring within these structures, raise the desire for site-specific immobilization of the molecule of interest. Here, we refine the single-molecule cut-and-paste technique by optical superresolution routines to immobilize single fluorescent molecules in the center of nanoapertures. By comparing their fluorescence lifetime and intensity to stochastically immobilized fluorophores, we characterize the electrodynamic environment in these nanoapertures and proof the nanometer precision of our loading method.

We characterize terahertz metamaterials by applying apertureless near-field microscopy with a bandwidth that covers the entire spectral response of the structures. The observations agree with the interpretation of the fundamental mode of the metamaterial. But the high frequency resonance shows properties that deviate from the common interpretation. We show that the high frequency response is governed by surface Plasmon excitations, which have a comparable oscillator strength as the fundamental mode.

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Static characterisation and fast switching processes of lateral β-Ga 2 O 3 metal oxide semiconductor field-effect transistors (MOSFETs) are presented. The investigated transistors with 10 mm gate width and 6 µm gate drain distance achieve on-state resistances of 5 Ω and saturation currents above 2.4 A. Hard switching in a double pulse test setup with an inductive load results in voltage slopes up to 65 V/ns at 300 V input voltage. After longer blocking times and higher DC voltages, a strong dynamic increase in on-state resistance occurs. Switching with an ohmic load and different load currents reveals only minor influence of the hot electron mechanism during the hard turn on. However, a clear influence of the turn-on gate drive voltage on the dynamic increase is observed, indicating a shift of the transfer characteristic due to charge trapping in the gate region. für Kristallzüchtung for providing the β-Ga 2 O 3 bulk crystal as well as A. Popp and S. Bin Anooz for the MOCVD layer deposition of n-type β-Ga 2 O 3. This work was funded by the Federal Ministry of Education and Research in Germany within the frame of the joint research project OXIKON, funding no. 03VP03711.

Since the atomic force microscope (AFM) has evolved into a general purpose platform for mechanical experiments at the nanoscale, the need for a simple and generally applicable localization of the AFM cantilever in the reference frame of an optical microscope has grown. Molecular manipulations like in single molecule cut and paste or force spectroscopy as well as tip mediated nanolithography are prominent examples for the broad variety of applications implemented to date. In contrast to the different kinds of superresolution microscopy where fluorescence is used to localize the emitter, we, here, employ the absorbance of the tip to localize its position in transmission microscopy. We show that in a low aperture illumination, the tip causes a significant reduction of the intensity in the image plane of the microscope objective when it is closer than a few hundred nm. By independently varying the z-position of the sample slide, we could verify that this diffraction limited image of the tip is not caused by a near field effect but is rather caused by the absorbance of the transmitted light in the low apex needle-like tip. We localized the centroid position of this tip image with a precision of better than 6 nm and used it in a feedback loop to position the tip into nano-apertures of 110 nm radius. Single-molecule force spectroscopy traces on the unfolding of individual green fluorescent proteins within the nano-apertures showed that their center positions were repeatedly approached with very high fidelity leaving the specific handle chemistry on the tip's surface unimpaired.