Modern digital sensors use two main types of systems; CCD (charge-coupled device) and CMOS APS (complementary metal oxide semiconductor active pixel sensor). Light is made of photons. A photon is an indivisible particle of light. The basic idea of ​​the photoelectric effect is the observation that electrons are emitted from energy levels when struck with sufficient energy by a photon. In this context, photons hit electrons inside the sensor and with sufficient energy escape into the conduction band, which is a higher energy level. This process is called dispersion. The electrons present in the capacitor are those that were in the conduction band and in the depletion region. This process occurs inside a semiconductor that sits inside the sensor. A semiconductor contains two bands: a valence band and a conduction band. The valence band does not allow electrons to move while, in the conduction band, electrons can move in their energy levels. This is because the valence band contains compact energy levels within the atom's lattice, while c...