We have studied the metallic behaviour in low density GaAs hole systems, and Si electron systems, close to the apparent two-dimensional metal-insulator transition. Two observations suggest a semi-classical origin for the metallic-like behaviour. Firstly the strength of the metallic behaviour is almost independent of the symmetry of the confining potential, and is predominantly determined by the low temperature resistivity (i.e. by k_F*l). Secondly the fractional decrease in conductivity with increasing temperature depends only on T/T_F, independent of the carrier density, in both systems.
@article{arxiv.cond-mat/0003295,
title = {On the metallic behaviour in dilute two-dimensional systems},
author = {A. R. Hamilton and M. Y. Simmons and M. Pepper and D. A. Ritchie},
journal= {arXiv preprint arXiv:cond-mat/0003295},
year = {2009}
}