Reach-thru silicon-germanium avalanche photodiode, design and 2D-simulation with synopsys TCAD

Research on Silicon based avalanche photodiodes has been seemingly increasing in the last decades, this as a result of its low cost in the fabrication process, providing higher gain and sensitivity by the low excess noise and dark current. The problem with silicon avalanche photodiodes is that the gain-bandwidth product is limited by the cutoff wavelength of silicon which depends upon its absorption coefficient. In this work I propose a p +-n:-p-n + Reach-Thru Silicon-Germanium based Avalanche Photodiode (APD) that takes the advantage of the wide absorption coefficient range ???of germanium and the high gain of silicon for the avalanche multiplication region. 2-D simulations and device characterization have demonstrated high gain and low excess noise at 1200nm resulting in a bandwidth-product of 293.97 GHz. The results reported in this document are very promising since the device will be able to operate at a very broad range of frequencies, opening new doors for these devices to applications in optical communications