Electrical Characterization of Semiconductor Nanostructures for Spintronics Applications

There has been much interest in semiconductor spintronics and, as a result, spin measurements. One of the relationships between the properties measured from the sample and further spin measurements is temperature. For interpretation of spin measurements, preliminary measurements for sheet resistance, sheet density, and mobility are made as a function of temperature. Semiconductor nanostructures, such as AlGaAs/GaAs two-dimensional electron gases, were grown by molecular beam epitaxi (MBE) and experimental data was obtained using the van der Pauw technique. Although there are several other techniques that have their own advantages, the van der Pauw technique is a good compromise that enabled efficient and reliable Hall effect measurements. The electrical characterizations of semiconductor material that were preformed used the Physical Properties Measurement System (PPMS) that controls temperature, magnetic field, and indirectly, current. The PPMS includes control software, cryostat, resistivity puck, and electronics controls. The cryostat allows measurements from virtually 0K to 400K. The resistivity puck is simply a platform for connecting wire leads to the sample as well as holding it. Enhancements were added to software and instrumentation to improve control and flexibility.