The photodetector, which converts an optical signal into an electrical signal, is a key component to any optical data communication link. When integrated into waveguides for on-chip communications, the photodetector requires a multi-physics electrical/optical analysis to accurately capture the effects of guiding light, photogeneration and current collection relevant to this type of device. Lumerical’s electrical and optical device solver products provide a powerful workbench for complete device simulation yielding characteristics such as responsivity, dark current and detection bandwidth.
For the optical simulation, FDTD can model in 3D the guiding of light into the active area of the device, absorption of the optical signal and resulting generation of electrical charge. For electrical simulation, CHARGE may be used to simulate the collection of the photogenerated charge within the active semiconductor region. The drift diffusion method employed by CHARGE accurately models the transport of charge within the semiconductor device, accounting for a wide variety of physical effects.
The photodetector workflow starts with optical simulations in FDTD. The generation rate is calculated from the optical absorption and used as a source in the subsequent electrical simulation in CHARGE to calculate the responsivity.
•Build a 3D model of your photodetector, including subcomponents such as waveguide routing sections, waveguide bends, and mode converters/tapers, as well as impurity concentration profiles and contact geometries. Geometric data can be imported from a STL or GDSII mask file
•Simulate the delivery of optical power to the device using the integrated eigenmode solver and mode source
•Accurately model absorbing and dispersive optical materials by taking advantage of built in models, or building you own models using external data and Lumerical’s Multi-Coefficient Materials
•Compute the electrical charge generation within the active area of the device, for further analysis in CHARGE
•Accurately model electronic transport in semiconductors using predefined material models, or customizing parametric models for mobility, surface and bulk recombination
•Include the generation of electrical charge via optical stimulus in your model. Detailed 2D/3D spatially varying optical generation profiles, as simulated in FDTD, are easily introduced to the simulation
•Simulate the current collection under various bias conditions and extract device characteristics such as dark current and responsivity
•Extract AC device characteristics such as bandwidth via small signal and transient analysis
•Optimize your device using the build-in parameter sweeps and optimization framework featuring an automatic particle swarm algorithm