An efficient room-temperature silicon-based light-emitting diode

There is an urgent requirement for an optical emitter that is compatible wi th standard, silicon-based ultra-large-scale integration (ULSI) technology( 1). Bulk silicon has an indirect energy bandgap and is therefore highly ine fficient as a light source, necessitating the use of other materials for th e optical emitters. However, the introduction of these materials is usually incompatible with the strict processing requirements of existing ULSI tech nologies. Moreover, as the length scale of the devices decreases, electrons will spend increasingly more of their time in the connections between comp onents; this interconnectivity problem could restrict further increases in computer chip processing power and speed in as little as five years. Many e fforts have therefore been directed, with varying degrees of success, to en gineering silicon-based materials that are efficient light emitters(2-7). H ere, we describe the fabrication, using standard silicon processing techniq ues, of a silicon light-emitting diode (LED) that operates efficiently at r oom temperature. Boron is implanted into silicon both as a dopant to forma p-n junction, as well as a means of introducing dislocation loops. The disl ocation loops introduce a local strain field, which modifies the band struc ture and provides spatial confinement of the charge carriers. It is this sp atial confinement which allows room-temperature electroluminescence at the band-edge. This device strategy is highly compatible with ULSI technology, as boron ion implantation is already used as a standard method for the fabr ication of silicon devices.