High Speed Surface Illuminated Si Photodiode Using Microstructured Holes for Absorption Enhancements at 900–1000 nm Wavelength

Abstract

A surface-illuminated silicon photodiode with both high speed and usable external quantum efficiency from 900 to 1000 nm wavelength is highly desirable for intra/inter data center Ethernet communications, high performance computing, and laser radar application. Such Si photodiodes have the potential for monolithic integration to CMOS integrated circuits which can significantly reduce the cost of data transmission per gigabit below one US dollar. To overcome silicon’s intrinsic weakness of absorption in these wavelengths, photon-trapping microstructured hole arrays are etched into the silicon surface, and the operational wavelengths of a high-speed silicon PIN photodiode are extended to 1000 nm. In this paper, the design and fabrication of such photon-trapping structures integrated into all-silicon photodiodes with significantly reduced absorption layer thicknesses to achieve high external quantum efficiency and fast response are presented. Different designs and geometries of the submicron holes on the sil...