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

Abstract

A remarkable increase in the quantum efficiency and light emission intensity has been observed as a function of the current density for n/sup +/pp/sup +/ 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 /spl times/ 10/sup -7/ to 5.8 /spl times/ 10/sup -6/ for current densities ranging from 1.6 /spl times/ 10/sup +2/ to 2.2 /spl times/ 10/sup +4/ A.cm/sup -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/sup +/ tip placed in a region of lower doping density opposite a highly conductive region. A best external quantum conversion efficiency of 5.8 /spl times/ 10/sup -6/ and light emission intensity of 0.1W per cm/sup 2/ were recorded at a current density level of 2.2 /spl times/ 10/sup +4/ at only 80 /spl mu/m total current and 8V operating condition. This corresponds to a light intensity emission intensity of approximately 1nW in a 1 /spl times/ 1 micron confined area on chip.