The metal-insulator transition (MIT) induced by a magnetic field in barely metallic and compensated n-type InP has been re-examined. Using a new analysis methods, the authors have determined the magnetic field for which the conductivity changes from a metallic behaviour to a variable-range hopping regime. On the metallic side of the MIT, the electrical conductivity is found to obey sigma = sigma ₀+mT^s down to 60 mK; the zero-temperature conductivity can be described by a scaling law with an exponent nu =1 and there is no evidence for a minimum metallic conductivity. As the MIT is approached, they observe a clear crossover from a T^1/2 to T^1/3 temperature dependence of the conductivity, which is related to a competition between two length scales: the correlation length and the interaction length.

We investigate the insulating and metallic behaviour in high mobility 2D Si-MOSFETs at very low temperature with parallel magnetic field. At the lowest carrier densities, insulating behaviour is observed with the resistivity increasing with decreasing temperature. As the carrier density increased a transition to metallic behaviour occurs. Despite exhibiting all the properties of the metallic behaviour observed in other material systems, localising corrections due both to weak localization and electron-electron interactions are still present in the metallic regime. For higher carrier densities the metallic regime becomes weaker and the saturation becomes visible at higher temperatures.