The energy distribution of electron states at SiC/SiO2 interfaces produced by oxidation of various (3C, 4H, 6H) SiC polytypes is studied by electrical analysis techniques and internal photoemission spectroscopy. A similar distribution of interface traps over the SiC bandgap is observed for different polytypes indicating a common nature of interfacial defects. Carbon clusters at the SiC/SiO2 interface and near‐interfacial defects in the SiO2 are proposed to be responsible for the dominant portion of interface traps, while contributions caused by dopant‐related defects and dangling bonds at the SiC surface are not observed.

The electronic structure of SiC/SiO2 interfaces was studied for different SiC polytypes (3C, 4H, 6H, 15R) using internal photoemission of electrons from the semiconductor into the oxide. The top of the SiC valence band is located 6 eV below the oxide conduction band edge in all the investigated polytypes, while the conduction band offset at the interface depends on the band gap of the particular SiC polytype. In the energy range up to 1.5 eV above the top of the SiC valence band, interface states were found. Their electron spectrum is similar to that of sp2-bonded carbon clusters in diamond-like a-C:H films suggesting the presence of elemental carbon at the SiC/SiO2 interfaces.

Low-temperature electrical measurements and photon-stimulated electron tunneling experiments reveal the presence of a high density of interface states at around 0.1 eV below the conduction band of 4H–SiC at its interface with thermally grown SiO2. These states, related to defects in the near-interfacial oxide layer, trap a considerable density of electrons from the SiC, and are likely responsible for the severe degradation of the electron mobility observed in the surface channel of 4H–SiC/SiO2 devices. The negative impact of the observed defects can be minimized by using SiC modifications (e.g., 6H, 15R, 3C) with a larger conduction band offset with the oxide than 4H–SiC leading to a largely reduced density of electrons trapped in the oxide.

The preoxidation cleaning of silicon carbide surfaces (3C, 4H, 6H polytypes) by exposing them to ultraviolet radiation and oxygen is shown to produce a significant improvement in the electronic properties of SiC/SiO2 interfaces. It is found that this treatment results in a removal of defect species, otherwise present at the SiC surface after thermal oxidation of SiC. Carbon clusters are proposed as the attacked species responsible for a substantial part of the SiC/SiO2 interface states.

An optical detection technique for a flow cytometer is described, which delivers high signal-to-noise discrimination without precision optics to enable a flow cytometer that can combine high performance, robustness, compactness, low cost, and ease of use. The enabling technique is termed “spatially modulated emission” and generates a time-dependent signal as a continuously fluorescing bioparticle traverses a predefined pattern for optical transmission. Correlating the detected signal with the known pattern achieves high discrimination of the particle signal from background noise. The technique is demonstrated with measurements of fluorescent beads flowing through a microfluidic chip.

The density of interface states Dit at SiC/SiO2 interfaces of different SiC polytypes (4H-, 6H- and 15R-SiC) is monitored and the origin of these states is discussed. The hydrogenation behavior of interface states in the temperature range from 250°C to 1000°C is studied by C-V and G-V investigations. The strong increase of Dit close to the 4H-SiC conduction band is attributed to defects located in the oxide (so-called “Near Interface Traps”).

Complete blood count and differentiation of leukocytes (DIFF) belong to the most frequently performed laboratory diagnostic tests. Here, a flow cytometry‐based method for label‐free DIFF of untouched leukocytes by digital holographic microscopy on the rich phase contrast of peripheral leukocyte images, using highly controlled 2D hydrodynamic focusing conditions is reported. Principal component analysis of morphological characteristics of the reconstructed images allows classification of nine leukocyte types, in addition to different types of leukemia and demonstrates disappearance of acute myeloid leukemia cells in remission. To exclude confounding effects, the classification strategy is tested by the analysis of 20 blinded clinical samples. Here, 70% of the specimens are correctly classified with further 20% classifications close to a correct diagnosis. Taken together, the findings indicate a broad clinical applicability of the cytometry method for automated and reagent‐free diagnosis of hematological disorders.

A chip-size spectrometer is realized by combining a linear variable band-pass filter with a CMOS camera. The filter converts the spectral information of the incident light into a spatially dependent signal that is analyzed by the camera. A fluidic platform is integrated onto the spectrometer for analyzing the fluorescence from moving objects. The target is continuously excited within an anti-resonant waveguide, and its fluorescence spectrum is recorded as the object traverses the detection area.