Ion Beam Processing for Silicon - Based Light Emission

In this talk an overview will be presented regarding the influence of ion irradiation effects and treatments on the formation of silicon-based light emission structures and devices. After a short overview to the complete field-as to my knowledge- we will concentrate on two activities performed at the FZR during the last years, (i) Blue-violet (400 nm) light emitters basing on Metal-Oxide-Silicon capacitors, and, (ii) Infrared (~1µm) light emitters basing on pn-junctions. Both approaches use ion beam processing as a key doping technique of advanced semiconductor technologies. For the first case we employed implantation of group IV ions (C, Si, Ge, Sn) into thermally silicon dioxide layers followed by an appropriate annealing step leading to electroluminescence effects with a power efficiency/external quantum efficiency of ~0.5/10 %. This preparation leads to the formation of semiconductor nanoclusters in the oxide matrix; the luminescence itself is related to defects. Comparing to other oxide production techniques like sputtering or evaporation it is shown that such high electroluminescence values are only possible on the base of ion beam processing, i.e. the combination of nanocluster synthesis and beam-induced energy deposition. For the second case we will demonstrate that appropriate boron implantation and annealing steps can lead to pn-junctions with two electroluminescence bands from bound excitons at 1.065 eV and around 0.95 eV. This effect needs local oversaturation of boron –which, of course, is only possible by ion implantation- leading to nanoclusters which produce the necessary doping and strain induced disturbances to the band structure.