17 Result(s)
within
Chapter
W. Wegscheider
-
Chapter and Conference Paper
Investigations on a dilute magnetic semicondutor (Ga1−xMnxAs) by conventional TEM and EELS
The Dilute Magnetic Semiconductor (DMS) Ga1−xMnxAs offers good prospects for the integration of ferromagnetic and semiconducting properties for use in future “spintronic” applications [1].
-
Chapter
The Structure and Dispersion of a Sharp Quantum Hall Edge Probed by Momentum-Resolved Tunneling
We present measurements of momentum-resolved magneto-tunneling from a perpendicular two-dimensional (2D) contact into integer quantum Hall (QH) edges at a sharp edge potential created by cleaved edge overgrow...
-
Chapter and Conference Paper
Cyclotron Resonance of Composite Fermions
The introduction of suitable fictitious entities occasionally permits to cast otherwise difficult strongly interacting many-body systems in a single particle form. We can then take the customary physical appro...
-
Chapter
Electronic Properties of AFM-Defined Semiconductor Nanostructures: Quantum Wires and Single Electron Transistors
The electron gas in AlGaAs heterostructures can be depleted below regions which are patterned with an atomic force microscope. This leads to laterally insulating regions across which in-plane gate voltages can...
-
Chapter
Validation: an Example
Validation of analytical methods can be regarded one of the most central topics in teaching analytical chemistry. While in the past it might have been feasible to demonstrate principles and practices of the mo...
-
Chapter and Conference Paper
Anisotropic state of two-dimensional electron gas in high Landau levels
When several Landau levels of a high mobility two-dimensional electron system are occupied, transport measurements reveal evidence for intriguing new phenomena at low temperature. Near half filling in the N=2 and...
-
Chapter and Conference Paper
Evidence for Ising Ferromagnetism and First-Order Phase Transitions in the Two-Dimensional Electron Gas
The two-dimensional (2D) electron gas in the quantum Hall regime offers unique possibilities to study the impact of many-body correlations under well-controlled conditions. One of the fields to which quantum H...
-
Chapter
Reliability of and measurement uncertainty for the determination of Au, Pd, Pt and Rh by ICP-MS in environmentally relevant samples
Due to low concentrations of noble metals in the environment the determination of these elements can be error prone even when the determinations are carried out by use of highly sensitive methods in combinatio...
-
Chapter and Conference Paper
Nanolithography on semiconductor heterostructures by local oxidation with an atomic force microscope
We demonstrate that tunable nanostructures in Ga[Al]As heterostructures can be patterned with an atomic force microscope (AFM). By application of suitable voltages to the conductive tip of the AFM, the sample ...
-
Chapter and Conference Paper
Atomically precise, coupled quantum dots fabricated by cleaved edge overgrowth
Recent progress in the fabrication of quantum dots by molecular beam epitaxy along three directions in space is reviewed. The optical properties of different sample structures consisting of individual quantum ...
-
Chapter
Binding of Electrons and Holes at Quantum Wires Formed by T-Intersecting Quantum Wells
Calculations are made of the properties of quantum wires formed by two or more GaAs/AlGaAs quantum wells intersecting at right angles in a T-configuration.This T-intersection geometry has taken on additional r...
-
Chapter
GaAs/AlGaAs quantum wire lasers and other low-dimensional structures fabricated by cleaved edge overgrowth
Cleaved edge overgrowth—a molecular beam epitaxy technique which incorporates two sequential growth steps along orthogonal crystal directions —was employed to fabricate lasers containing an array of 22 quantum...
-
Chapter and Conference Paper
Single-Mode Stimulated Emission in a Quantum-Wire Laser Fabricated by Cleaved-Edge Overgrowth
We have used the molecular beam growth technique, we call Cleaved Edge Overgrowth to fabricate highly efficient lasers, which operate in the ID quantum limit. The active region of our laser consists of quantum...
-
Chapter
Strained Layer Heterostructures and Superlattices Based on Group IV Elements
Heterostructures and superlattices based on the group IV elements Si, Ge and α-Sn are fabricated by low temperature molecular beam epitaxy. The main problems of high quality growth are the large lattice mismat...
-
Chapter
Phonons and Optical Properties of Si/Ge Superlattices
Short period Si/Ge superlattices are new semiconductor materials whose band structure and consequently whose electrical and optical properties can be changed in a wide range. New device applications are expect...
-
Chapter
Realization of Short Period SI/GE Strained-Layer Superlattices
We present experimental studies of growth, structural, and phonon properties of ultrashort period Si/Ge superlattices. The samples are grown by molecular beam epitaxy both on Si and Ge substrates with differen...
-
Chapter
Optimization Strategies for Chromatographic Analysis of Multi-Component Mixtures
In column-chromatographic analysis of biological samples, complex chromatograms with long elution times are often encountered. Once the general separation conditions have been chosen, e.g. type and mode of use...
