Incident light with an energy of hv>Eg excites an electron and causes it to jump from the valence...
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Transcript of Incident light with an energy of hv>Eg excites an electron and causes it to jump from the valence...
Incident light with an energy of hv>Eg excites an electron and causes it to jump from the valence band to the conduction band, thereby creating an electron-hole (e-h) pair.
Chapter 7Optical detectors
An incident photon can cause the production of e-h pairs in three differentregions (A, B and C) in the p-n diode. However, rapid detection is only achievable in B, the depletion region.
Schematic description of field strength variations in a p-n diode. Reverse voltage and external load applied.
By applying an intrinsic layer between the p- and n-layers, the absorptionregion obtained is much broader than that of a p-n diode.
A high reverse voltage of 100-300 V gives the electrons such high kinetic energy that multiplication of e-h pairs occurs throughcollision ionization.
The responsivity of a photodiode is dependent both on the wavelength of the incident light and the materials used.