Theory of metal-insulator transitions in gated semiconductors

It is shown that recent experiments indicating a metal-insulator transition in 2D electron systems can be interpreted in terms of a simple model, in w hich the resistivity is controlled by scattering at charged hole traps loca ted in the oxide layer. The gate voltage changes the number of charged trap s which results in a sharp change in the resistivity. The observed exponent ial temperature dependence of the resistivity in the metallic phase of the transition follows from the temperature dependence of the trap occupation n umber. The model naturally describes the experimentally observed scaling pr operties of the transition and the effects of magnetic and electric fields. [S0031-9007(98)08103-4].