Martin Eickhoff

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The photoluminescence (PL) response of GaN/AlGaN nanowire heterostructures (NWHs) to hydrogen and oxygen between room temperature and 300 °C is reported. Exposure of Pt-coated NWHs to H2 leads to an increase of the PL intensity attributed to the suppression of surface recombination by local dipole fields of adsorbed atomic hydrogen. When exposed to O2,(More)
We report on the effect of Mg doping on the properties of GaN nanowires grown by plasma assisted molecular beam epitaxy. The most significant feature is the presence of triple-twin domains, the density of which increases with increasing Mg concentration. The resulting high concentration of misplaced atoms gives rise to local changes in the crystal structure(More)
We report the observation of transverse-magnetic-polarized infrared absorption assigned to the s-p(z) intraband transition in Ge-doped GaN/AlN nanodisks (NDs) in self-assembled GaN nanowires (NWs). The s-p(z) absorption line experiences a blue shift with increasing ND Ge concentration and a red shift with increasing ND thickness. The experimental results in(More)
The present paper compares three different kinds of semiconductor gas sensing materials: metal oxides (MOX), hydrogenterminated diamond (HD), and hydrogenated amorphous silicon (a-Si:H). Whereas in MOX materials oxygen is the chemically reactive surface species, HD and a-Si:H are covalently bonded semiconductors with hydrogenterminated surfaces. We(More)
Aberration corrected scanning transmission electron microscopy (STEM) with high angle annular dark field (HAADF) imaging and the newly developed annular bright field (ABF) imaging are used to define a new guideline for the polarity determination of semiconductor nanowires (NWs) from binary compounds in two extreme cases: (i) when the dumbbell is formed with(More)
We investigate the origin of the surface conductivity of H-terminated diamond films immersed in aqueous electrolyte. We demonstrate that in contrast to the in air situation, charge transfer across the diamond interface does not govern the surface conductivity in aqueous electrolyte when a gate electrode controls the diamond/electrolyte interfacial(More)
2010 WILEY-VCH Verlag Gmb Wide-bandgap semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) have received increasing attention as potential components in advanced organic/inorganic hybrid systems. In both of these materials, the Fermi level can be varied over a wide energy range by controlled impurity incorporation. Moreover, they exhibit(More)
We introduce two new approaches for near-real-time, high-precision tracking of the refractive index of the ambient atmosphere. The methods can be realized at low cost and are expected to have important practical application in those accurate dimensional metrology applications employing interferometry in air. A valuable potential application is the control(More)
We have characterized the photodetection capabilities of single GaN nanowires incorporating 20 periods of AlN/GaN:Ge axial heterostructures enveloped in an AlN shell. Transmission electron microscopy confirms the absence of an additional GaN shell around the heterostructures. In the absence of a surface conduction channel, the incorporation of the(More)
We present a novel approach for self-assembled growth of GaN quantum wires (QWRs) exhibiting strong confinement in two spatial dimensions. The GaN QWRs are formed by selective nucleation on {112[combining macron]0} (a-plane) facets formed at the six intersections of {11[combining macron]00} (m-plane) sidewalls of AlN/GaN nanowires used as a template. Based(More)