Growth and processing of GaAs/AlGaAs heterostructures

III-V NANOLAB is a laboratory, or instrument center, that is run jointly by MIC and the Niels Bohr Institute, Copenhagen University (NBI), where it is also located. It is supported by the Danish Research Councils and its purpose is to grow and process semiconductor heterostructures on a nanometer scale for the basic and strategic research programs at NBI and MIC. GaAs/AlGaAs heterostructures of excellent quality are grown by molecular beam epitaxy (MBE) on (001)-oriented substrates to produce two-dimensional electron gasses of high mobility. These structures are vital for the processing of components on a nanometer scale for the studies of mesoscopic electron transport taking place at the NBI. Multiple quantum wells and superlattices of GaAs/AlGaAs are grown for the studies of linear and nonlinear optical properties of quasi two-dimensional quantum systems. Optimization of MBE epitaxial growth on higher index surfaces, (110) in particular, has also been performed. A cleaved edge overgrowth technique has been implemented by which one-dimensional quantum wire systems is being grown. Growth of low-temperature GaAs has been optimized in order to produce a photoconductive material with a very short carrier lifetime for use in ultrafast photoconductive switching and sampling. III-V NANOLAB also produces custom designed samples on a commercial basis, e.g. quantum-Hall effect samples for resistance standards and quantum well samples for GaAs diode lasers.