Experimental evidence of a Mott transition in highly doped two-dimensional confined structures

Mott transition in a two-dimensional electron gas in a doped GaAs∕AlGaAs quantum well is experimentally studied. The impurity band is observed at a doping level up to 10¹⁸0.3em0excm^-3. This value is two orders of magnitude higher than the Mott transition in bulk GaAs (about 10¹⁶0.3em0excm^-3). This high density Mott transition is explained by a quantitative model involving the donor distribution in the wells.