Silicon p-i-n Photodiode with Reduced Background Radiation

The article examines the possibility of minimizing the influence of background radiation on the useful signal of silicon four-element p-i-n photodiodes. When examining the sources, it was established that optical filters are an effective means of avoiding noise of optical origin. A number of variants of optical filters were analyzed, and it was established that the optimal material for making filters is silicon, because it has its own absorption edge at a wavelength of about 1000 nm. To reduce the reflection coefficient, an anti-reflective coating was formed on the surface of the silicon filters. It was established that with an increase in the thickness of the filter, the transmission coefficient decreases due to a decrease in the radiation intensity during propagation in the absorbing medium. It is seen that when the thickness of the filter changes, its absorption edge shifts toward shorter wavelengths. the obtained optical filters allow to effectively avoid the influence of background radiation on the useful signal of the photodiode. The disadvantage of the proposed filters is an increase in the absorption coefficient when the thickness of the samples increases. The optimal thickness is 170$\mu$ m, but this thickness contributes to some deviation from the maximum of the spectral characteristic.