Taguchi optimization of a SOI-based lateral PIN photodiode using SiGe/Si multilayer quantum well

Abstract

Silicon-on-insulator (SOI) based SiGe quantum well infrared pin photodiode has the potential of being a serious candidate for applications in sensing applications as well as in optical fiber communications. The objective of this paper is to optimize the process parameters for a SOI-based lateral PIN photodiode using SiGe/Si multilayer quantum well (MQW) to obtain high responsivity, frequency response, quantum efficiency and low transient time. An L9 array from Taguchi method was used to optimize the device design. Four process parameters were chosen, namely the intrinsic region length, photo-absorption layer thickness, the incident optical power and the bias voltage. Two noise factors i.e. the time and temperature of the n-well diffusion process were also used to make the device design insensitive to variation in selected fabrication parameters. ATHENA and ATLAS module from Silvaco Int. were used for the fabrication simulation and electrical characterization. The results obtained for responsivity, frequency response and transient time after the optimization approach were 0.87 A/W, 20 GHz and 1.75 x 10-11 respectively which correspond to the optimization value for the intrinsic region length of 6 μm, photo-absorption layer thickness of 0.505 μm, incident optical power of 0.5 mW/cm2and bias voltage of 3.5 V. As a conclusion, the optimum solution in achieving the desired high speed photodiode was successfully predicted using Taguchi optimization method. The percent of improvement for responsivity and frequency responses are 22.3% and 5.26% respectively.