The article presents a quantum mechanical model for the electron field emission from semiconductor surfaces covered by dielectric layers. By systematically connecting electronic wave functions at. various interfaces, the model obtains in a unified manner the field emission current density from both clean and dielectric-covered semiconductor substrates. No energy quantization is imposed for the interface layer and thermodynamic nonequilibrium is allowed between the conduction electrons from the interface (accumulation) layer and those of the bulk. The model is applied to study the electron field emission from Si tips covered by ultrathin oxide layers, and also to explain the resonance effects observed in field emission from Si covered by thicker dielectric layers. (c) 2005 American Vacuum Society.