Carrier localisation in inversion layers and impurity bands

This report is principally concerned with our work on the physics of transport in two dimensional systems. We show that the logarithmic corrections to the conductance of Si inversion layers arise from both interaction and localization effects. Application of a magnetic field suppresses localization and enhances the role of interactions. At certain values of magnetic field both effects can be present, but with a different stability against increasing temperature. Consequently, heating the electron gas with an electric field allows the observation of a transition between them. Decreasing elastic scattering decreases the magnetic field required to suppress localization, as the enhancement of the interaction effect arises from spin a clear separation is obtained between the mechanisms.