A silicon/iron-disilicide light-emitting diode operating at a wavelength of 1.5 mu m

Although silicon has long been the material of choice for most microelectronic applications, it is a poor emitter of light (a consequence of having an 'indirect' bandgap), so hampering the development of integrated silicon optoelectronic devices, This problem has motivated numerous attempts to develop silicon-based structures with good light-emission characteristics(1), particularly at wavelengths (similar to 1.5 mu m) relevant to optical fibre communication, For example, silicon-germanium superlattice structures(2) can result in a material with a pseudo-direct bandgap that emits at similar to 1.5 mu m, and doping silicon with erbium(3) introduces an internal optical transition having a similar emission wavelength, although neither approach has led to practical devices, In this context, beta-iron disilicide has attracted recent interest(4-12) as an optically active, direct-bandgap material that might be compatible with existing silicon processing technology, Here we report the realization of a light-emitting device operating at 1.5 mu m that incorporates beta-FeSi2 into a conventional silicon bipolar junction. We argue that this result demonstrates the potential of beta-FeSi2 as an important candidate for a silicon-based optoelectronic technology.