Study the effect of temperature variation and intrinsic layer thickness on the linear response of a PIN photodetector: A finite element method approach

Perhaps mentioning the place of Silicon Valley semiconductor companies in business and technology is enough to remind the place of semiconductors in today's world. One of the applications of semiconductors is in manufacturing detection devices. This research aims to investigate the linearity of the response of a PIN photodetector to incident light. For this purpose, we will first simulate a PIN photodetector using COMSOL Multiphysics 6.0 software. Then we expose this photodetector to the light emitted from the scintillator and check the linearity of the response in the range of wavelengths irradiated to it. The research was done on photodetector PINs that are made of two semiconductor materials, GaAs and Si. The temperature and thickness of the intrinsic layer of a photodetector greatly affect its outputs, such as Current Terminal, Quantum Efficiency, and Responsivity. Therefore, the effect of these two parameters on the linearity of the output response of a photodetector has been investigated. To monitor the linearity of the photodetector output in each mode, a Linear Fitting has been applied to the output of the photodetectors using the Origin Pro software, and the linearity of the output data has been controlled from the R-Square and Adjusted R-Square of this fitting. The investigation illustrates that the response of GaAs is more linear than that of Si in similar cases. For example, the GaAs photodetector in the thickness of 8 μm and at the temperature of T = 70 °C has Adjusted R-Square = 0.9972. In contrast, the Si photodetector has Adjusted R-Square = 0.9178 under the same conditions.