number of planar silicon light-emitting devices are designed and realized in standard 1.2 and 2-mm complementary metal oxide semiconductor (CMOS) integrated circuitry. The devices yield optical power intensities of up to 0.2 mW/cm2 (up to 0.2 nW per 100 mm2) at operating voltages from 4 to 31 V and at currents of 0.1 to 10 mA, respectively. The devices emit light in a broad spectrum from 450 to 800 nm with characteristic peaks at 500 and 650 nm. The emitted intensity of the devices is three to four orders of magnitude higher than the low-frequency detectability limit of integrated Si optical pn detectors utilizing similar areas on chip as the light sources. Initial investigations indicate that the devices have a very fast inherent modulation bandwidth capability. The devices show potential for on-chip electro-optical communication and chip-tochip electro-optical communications.