Electron field emission from semiconductors through oxide layers: possibletransport effects

The field electron emission from a semiconductor (with special emphasis on silicon) occurring through an oxide layer is considered. The oxide thicknes s is taken large enough to allow for transport effects. The electrons an in jected from the conduction band of the semiconductor into the conduction ba nd of the oxide, through the interfacial potential barrier. The applied ele ctric field (which deeply penetrates the oxide), the position gradient of t he electron concentration and the scattering events equilibrate to an elect ron distribution that accumulates near the emitting site. Since the conditi ons at the semiconductor-oxide interface are fixed, the accumulation effect increases with the oxide thickness. Consequently, an increase of the emiss ion current density at the oxide-vacuum interface is obtained. The total el ectron current invariance implies then a reduction of the effective emittin g surface area with. corresponding possible increase of the local Joule hea ting. This could provide an alternative insight to the local damaging mecha nisms of the oxidized emitting surfaces. (C) 1999 Elsevier Science B.V. All rights reserved.