An All-Silicon Integrated Light Emitter Technology

The need for optoelectronic devices that are compatible with integrated circuit manufacturing technology has stimulated research in all-silicon light-emitting devices. Since crystalline silicon is an indirect bandgap semiconductor, its luminescence efficiency is low (~10-6%). Several approaches have been proposed to correct this deficiency [1,2], but so far porous silicon, which produces high-efficiency room-temperature visible photoluminescence [3], has attracted the most interest. Figure 1 shows the range of wavelengths over which strong luminescence can be achieved [4]. A major limitation of this material is that it is very reactive and inherently fragile, and thus cannot readily be integrated with conventional silicon process technology. We have overcome these limitations and we show that silicon-rich silicon oxide (SRSO) prepared by partial oxidation of porous silicon appropriate light-emitting and carrier transport properties and is compatible with conventional processing techniques. SRSO-based visible light-emitting devices (LEDs) have been successfully integrated into a standard bipolar fabrication sequence. This is the first demonstration of an all silicon visible light emitter / bipolar transistor optoelectronic integrated circuit.