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-μm CMOS process without any modification. The Si-LEDs with a new threeterminal 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 μW 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 · μm -2 the power conversion efficiency and external quantum efficiency are ~2 × 10 -6 and 8.3 × 10 -6 , respectively, higher than all other forward-biased Si-LEDs previously reported to have used CMOS processes without any modification.