LIGHT-EMITTING DEVICES IN INDUSTRIAL CMOS TECHNOLOGY

Two different unmodified industrial CMOS processes have been used for the integration of highly interdigitated pn structures. Under forward bias these pn junctions emit narrow-band infrared light at 1160 nm wit h an electrical-to-optical power conversion efficiency of typically 10 (-4). The same junctions show broad-band visible-light emission betwee n 450 and 800 nm in the avalanche breakdown region under reverse bias with efficiencies of the order of 10(-8). This is already enough for a first few practical applications as light-emitting devices (LEDs). No satisfactory explanation for this emission effect, fitting all the ex perimentally observed electro-optical and physical properties of our s ilicon LEDs, has been found yet.