Efficient low voltage, high frequency silicon CMOS light emitting device and electro-optical interface

A silicon light emitting device was designed and realized utilizing a standard 2-μm industrial CMOS technology design and processing procedure. The device and its associated driving circuitry were integrated in a CMOS integrated circuit and can interface with a multimode optical fiber. The device delivers 8 nW of optical power (450-850 nm wavelength) per 20 μm diameter of chip area at 4.0 V and 5 mA. The device emits light by means of a surface assisted Zener breakdown process that occurs laterally between concentrically arranged highly doped n⁺ rings and a p⁺ centroid, which are all coplanarly arranged with an optically transparent Si-SiO₂ interface. Theoretical and experimental determinations with capacitances and series resistances indicate that the device has an intrinsic high-frequency operating capability into the near gigahertz range.