FM - solid state physics and physics of materials

FM.QHE - Quantum Hall Effect

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Carrier concentration and mobility are essential parameters in the electrical characterisation of semiconductor materials. They can be determined by Hall-Effect and resistivity measurements. Moreover, the temperature dependence of these quantities can be used to extract further information about the material, such as activation energy or relevant scattering mechanisms. For example, two-dimensional electron gases (2DEGs) exhibit a fundamentally different temperature dependence of the mobility as compared to bulk material, due to the absence of scattering from ionised impurities in the 2DEG channel.

Two-dimensional electron gases with high mobility develop plateaus in the Hall resistance at high magnetic fields (Quantum-Hall-Effect,QHE).

In this lab, classical Hall-Effect measurements will be performed on various semiconductor heterostructures. In this way, basic techniques of electrical characterization and low-temperature physics are demonstrated. The results will be analysed in detail, together with the data set of a QHE measurement obtained for the same sample.

IV. Physikalisches Institut, B04.104