Quantum efficiency of CMOS integrated silicon n+pp+ light-emitting devices as a function of current density

A remarkable increase in the quantum efficiency and light emission intensity has been observed as a function of the current density for n⁺pp⁺ silicon integrated light emitting devices which were fabricated with standard silicon CMOS technology. An increase of about two orders of magnitude for the quantum efficiency from 1.6 × 10^-7 to 5.8 × 10^-6 for current densities ranging from 1.6 × 10⁺² to 2.2 × 10⁺⁴ A.cm^-2 is observed. The highest efficiency devices operate in the pn reverse breakdown avalanche breakdown mode and utilize current density increase by means of electrical field density confinement at a wedge shaped n⁺ tip placed in a region of lower doping density opposite a highly conductive region. A best external quantum conversion efficiency of 5.8 × 10^-6 and light emission intensity of 0.1W per cm² were recorded at a current density level of 2.2 × 10⁺⁴ at only 80 μm total current and 8V operating condition. This corresponds to a light intensity emission intensity of approximately 1nW in a 1 × 1 micron confined area on chip.