Physical modeling and design of thin-film SOI lateral PIN photodiodes

Lateral PIN diodes on thin-film silicon-on-insulator (SOI) substrates are photodetectors of prime interest for UV and fast IR applications. We present numerical simulations and a simple but accurate way to implement 1-D internal physical modeling of such devices. This modeling allows for the optimization of their external and macroscopic performances such as quantum efficiency and output current as a function of design parameters such as intrinsic length of the diode. Speed and dark current performances versus the intrinsic length are also addressed, and design tradeoffs are illustrated by concrete applications. For diodes with intrinsic lengths between 2 to 4 μm, our results predict quantum efficiencies of 56% to 60% at a 400-nm wavelength, with bandwidth of 1 to 10 GHz and a dark current of around 1 pA for a total diode area of 75×75 μm² in a 0.12 μm partially depleted SOI technology.