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

Abstract

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 $\,\cdot \,\mu $ $\mathrm{m}^{-2}$ the power conversion efficiency and external quantum efficiency are $\sim 2\times 10^{\mathrm {\mathbf {-6}}}$ and $8.3\times 10^{\mathrm {\mathbf {-6}}}$ , respectively, higher than all other forward-biased Si-LEDs previously reported to have used CMOS processes without any modification.