The Observation of a Percolation-Induced 2D Metal-Insulator Transition in AlAs

Abstract

The nature of the metal-insulator transition at zero magnetic field in two-dimensional systems has remained a controversial enigma since the pioneering realization of the metallic behavior in high mobility Si-MOSFETs. In this paper the density (n) dependence of the conductivity of the two-dimensional electron gas in aluminum arsenide was analyzed in the metallic side (n ≥ 0.59×10^(11) cm^(-2)) at very low temperature. Our study reveals an inhomogeneity driven percolation type transition to an insulating state due to the breakdown of screening in the random charged impurities disordered background. The critical density found under this assumption is lower than that assumed by observing the sign of the temperature coefficient of conductivity. Experimental data are reprinted with permission from [S. J. Papadakis and M. Shayegan, Phys. Rev. B 57, R15068 (1998)].