This thesis focuses on the electronic transport properties and low temperature quantum effects of mesoscopic GaAs/InAs core/shell nanowires. This radial nanowire heterostructure combines an electrically insulating GaAs core with a highly conductive InAs shell. Owing to this alignment, the movement of the conduction electrons is limited to a ring-li...
In this thesis, the growth and structural properties of III-V semiconductor nanowires and nanowire heterostructures are studied. These nanowires represent structures suitable for both fundamental physics and applications in electronic devices such as (tunnel) field effect transistors. The III-V nanowires are grown with molecular beam epitaxy, high ...
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...
An overview of quantum cascade detector technology for the near- and mid-infrared wavelength range will be given. Thanks to photovoltaic instead of photoconductive operation, quantum cascade detectors offer great opportunities in terms of detection speed, room temperature operation, and detectivity. Besides some crucial issues dealing with fabricat...
This paper gives an overview on the design, fabrication, and characterization of quantum cascade detectors. They are tailorable infrared photodetectors based on intersubband transitions in semiconductor quantum wells that do not require an external bias voltage due to their asymmetric conduction band profile. They thus profit from favorable noise b...
We present experimental results of THz detection signal dependence on the magnetic field. THz radiation was detected with AlGaAs/GaAs high electron mobility transistor where 2D plasma excitations are responsible for the detection signal appearance. We observe both Shubnikov - de Haas oscillations and cyclotron resonance in the detection signal. Fou...
We present photoluminescence measurements under intense magnetic fields (B up to 30 T) in n-doped indium nitride samples with carrier concentration ranging from about 7.5x10(17) cm(-3) to 5x10(18) cm(-3). The observation of transitions involving several Landau levels permits to determine the carrier-reduced mass mu around the Gamma point. Depending...
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...
