fotodiód

A photodiode is a semiconductor device that converts light into an electrical current. It is essentially a p-n junction or a p-i-n junction made of semiconductor material. When photons strike the photodiode, they can generate electron-hole pairs. If this occurs in or near the depletion region of the junction, the built-in electric field will separate these charge carriers, causing current to flow. This current is directly proportional to the intensity of the incident light.

Photodiodes are typically used to detect light and measure its intensity. They can operate in two primary modes: photovoltaic mode and photoconductive mode. In photovoltaic mode, the photodiode acts like a small solar cell, generating a voltage when illuminated. This mode is useful for low-light applications where external power is not desired. In photoconductive mode, a reverse bias voltage is applied across the photodiode. This widens the depletion region, increasing sensitivity and response speed, but also introduces dark current, which is a small current that flows even in the absence of light.

Common applications for photodiodes include light meters, remote controls, optical communication systems, medical imaging, and security systems. Their small size, fast response time, and ability to detect a wide range of light wavelengths make them versatile components in many electronic circuits. Different semiconductor materials are used to manufacture photodiodes, allowing them to be sensitive to specific parts of the light spectrum, from ultraviolet to infrared.