Simulation of Ge on Si Photodiode with photon-trapping micro-nano holes with -3dB bandwidth of >60 GHz at NIR wavelength

TL;DR

This paper presents a Ge-on-Si photodiode with nano-microholes that achieves over 60 GHz bandwidth and high optical absorption efficiency, suitable for high-speed optical interconnects.

Contribution

It introduces a novel nanostructured Ge-on-Si photodiode design with optimized micro-nanoholes for enhanced absorption and ultra-fast performance at near-infrared wavelengths.

Findings

Bandwidth >60 GHz achieved

Optical absorption efficiency above 80%

Nano-microhole optimization improves performance

Abstract

The study proposes an ultra-thin back side illuminated (BSI) and top-illuminated, Ge on Si photodetector (PD), for 1 to 1.4 microns wavelength range. The Ge thickness of 350 nm allows us to achieve high-speed performance at >60 GHz, while the nanostructure at the bottom of the Ge layer helps to increase the optical absorption efficiency to above 80%. The BSI PD allows the PD or PD array wafer to be stacked with an electronic wafer for signal processing and transmission for optical interconnect applications such as short-reach links in data centers. Nano-microhole parameters in randomized composite formation on the bottom layer are optimized with Monte-Carlo molecular dynamics simulations incorporating charge transport to enable wide-spectral, highly efficient, and ultra-fast PDs.