Elektrische Eigenschaften oxidischer thermischer Spritzschichten wurden bisher nur wenig und nicht zusammenhängend untersucht. In der vorliegenden Arbeit wird erstmalig das Werkstoffsystem thermisch gespritzter Schichten mit den Eckpunkten Al²O³, TiO² und Cr²O³ systematisch untersucht und dargestellt. Besonders attraktiv hinsichtlich der Anwendung ...
The potential application of graphene nanoplatelets as electrode material in supercapacitors with high energy density was investigated. The electrode were prepared with commercially available graphene nanoplatelets before and after being functionalized with MnO2 particles, and with those electrochemically exfoliated from graphite. The morphology, s...
In this paper, we give an overview of quantum cascade detector technology for the near- and mid-infrared wavelength range. Thanks to their photovoltaic operating principle, the most advanced quantum cascade detectors offer great opportunities in terms of high detection speed, reliable room temperature operation, and excellent Johnson noise limited ...
The influence of the growth method on the surface potential and thus on the sheet carrier concentration of GaN capped Al(x)Ga(1-x)N/GaN heterostructures was evaluated. Nominally undoped low pressure metal-organic vapor-phase (MOVPE) and plasma-assisted molecular beam epitaxial (PA-MBE) grown structures with an Al-content between 12% and 30% yield c...
We present large-area emitters based on GaInAsN which show efficient THz emission for excitation wavelengths up to 1.35 µm. The substrate material consists of a 1000 nm Ga1-yInyAs1-xNx (y = 0.11 and x = 0.04) layer grown by molecularbeam epitaxy on semi-insulating GaAs. On top there is an additional GaAs/Al0.3Ga0.7As heterostructure with thicknesse...
High electron mobility transistor material and device properties based on AlxGa1-xN/GaN heterostructures with an Al-content ranging from 12 to 35% are presented. The Al-content of the low pressure metal-organic vapor-phase epitaxy grown samples on semi-insulating SiC and sapphire was measured by high resolution X-ray diffraction; carrier concentrat...
Detection of THz radiation by a high electron mobility (HEMT) GaAs/GaAlAs transistor was investigated at 4 K as a function of the magnetic field B. The detection signal (a source - drain photovoltage appearing as a response to THz radiation) was found to be periodic in B(exp -1), i.e., it showed Shubnikow - de Haas oscillations. A Fourier transform...
A bow-tie InGaAs with broken symmetry has been designed for terahertz detection at room temperature. An active part of the detector consists of a two-dimensional electron gas which is heated non-uniformly with incident radiation. Main detector performances are operation in a passive scheme, flat frequency response up to 1 THz, the voltage sensitivi...
GaAs/ALGaAs and GaN/AlGaN high electron mobility transistors were used as detectors of THz electromagnetic radiation at liquid helium temperatures. Application of high magnetic fields led to the Shubnikov-de Haas oscillations of the detection signal. Measurements carried out with a simultaneous modulation of the intensity of the incident THz beam a...
The surface potential of GaN:Si, of fundamental interest for knowledge of the electrostatic potential and electric field strength, is determined for Si doping in the device relevant range from 6x10(17) cm(-3) to 2.3x10(19) cm(-3), in layers grown by low-pressure metal-organic vapor-phase epitaxy. Comparing the Si doping concentration, measured by s...
