Electron field emission from semiconductors through oxide layers: possible transport effects

The field electron emission from a semiconductor with special emphasis on silicon.occurring through an oxide layer is considered. The oxide thickness is taken large enough to allow for transport effects. The electrons are injected from the conduction band of the semiconductor into the conduction band of the oxide, through the interfacial potential barrier. The applied electric field which deeply penetrates the oxide., the position gradient of the electron concentration and the scattering events equilibrate to an electron distribution that accumulates near the emitting site. Since the conditions at the semiconductor-oxide interface are fixed, the accumulation effect increases with the oxide thickness. Consequently, an increase of the emission current density at the oxide–vacuum interface is obtained. The total electron current invariance implies then a reduction of the effective emitting surface area with a corresponding possible increase of the local Joule heating. This could provide an alternative insight to the local damaging mechanisms of the oxidized emitting surfaces. q1999 Elsevier Science B.V. All rights reserved.