High Optical Power Density Forward-Biased Silicon LEDs in Standard CMOS Process

This letter presents three low-operating-voltage silicon-based light-emitting devices (Si-LEDs) designed and made in a commercial standard 0.18-mu m CMOS process without any modification. The Si-LEDs with a new three-terminal and wedge-shaped forward-biased carrier-injection-type p(+)-n junction structure, have high optical powers. The output power increases by two orders of magnitude up to 1.78 mu W without saturation when the forward current is increased from 20 mA to 200 mA. The light-emitting area is the n-type drift region between the n(+) region and p(+) region. When the forward current increases to 200 mA, the optical power density exceeds 30 nW . mu m(-2) the power conversion efficiency and external quantum efficiency are similar to 2 x 10(-6) and 8.3 x 10(-6), respectively, higher than all other forward-biased Si-LEDs previously reported to have used CMOS processes without any modification.