Numerical Modeling of the Spectral and Diffuse Reflectance of Silicon Photodiodes
Tao Xu and Yan Yan Suo
The general model describing the spectral reflectance of silicon photodiodes is based on the thin-film Fresnel formulas and the known refractive indices of the materials of the photodiodes. It is amended in this paper by considering the diffuse reflectance of the light in Si materials. A precision spectrometer is developed to measure the specular and diffuse reflectance of a silicon photodiode over the wavelength range from 400 to 900 nm. The results are compared with the corresponding values predicted by the general model and the new model. It is found that the predicted values by the general model show agreement with the experimental values of specular reflectance and show obvious difference with the total reflectance in visible and infrared region. The new model, which considers the diffuse reflection, can predict the total reflectance well.
Keywords: Electro-optical effects, lasers, light propagation, light scattering, modeling, photodiodes, spectral analysis.