Spray deposited heavy doped indium oxide film as an efficient hole supplier in silicon light-emitting diodes

Abstract The role of a spray deposited tin-doped indium oxide film (ITO) in forward-biased surface-barrier structures fabricated on silicon, from which an efficient radiation emission is obtained, is explained in this work. Such structures present the properties of an induced p–n junction. To achieve a high injection of holes from the p-inversion layer into the n-type silicon substrate, the tin-doped indium oxide film must be a good supplier of holes to maintain this inversion layer. An efficient delivery of holes is possible only if the conduction band of the degenerate n-type tin-doped indium oxide film contains a sufficient number of unoccupied energetic states below the Fermi level that is not less than the surface concentration of holes at the inversion layer. Under such a condition, electrons from the silicon valence band can occupy these empty energetic levels, leaving an equal number of empty energetic states (holes) in the silicon valence band. Our calculations demonstrate the legitimacy of our model for structures with heavily doped indium oxide. The applicability of this model to other high barrier metal–semiconductor contacts is also shown.