Integrating bipolar junction transistors with silicon-based light-emitting devices

Silicon-based optoelectronic devices enable the realization of optoelectronic systems that are compatible with integrated circuit manufacturing technology. This work reports on silicon-based visible light-emitting devices (LEDs) that have been successfully integrated into a standard bipolar fabrication sequence. The basic LED structure consists of a 0.5-1.0μm thick silicon-rich silicon oxide (SRSO) active light-emitting layer formed on a p-type silicon wafer by partial oxidation of porous silicon (PSi), with an n⁺ doped polysilicon cathode. The LEDs exhibit bright electroluminescence (EL) with a spectral peak between 1.75 and 1.90eV. The LEDs are connected in a common-emitter configuration to integrated vertical pnp bipolar driver transistors. This is the first demonstration of an all-silicon visible light emitter / bipolar transistor optoelectronic integrated circuit. The LED device fabrication, process integration, and optoelectronic device characteristics are discussed.