Photodiode
A photodiode is a light sensitive semiconductor. It is a type of photodetector capable of changing (or converting) light into either current or voltage, depending upon its connections.[1] It is a diode and wired with reverse biasing so that when in the dark, only a small amount of current, known as dark current, will flow. When in the light, a current known as photocurrent flows through the diode.
Photodiodes may contain optical filters, built-in lenses, and may have large or small surface areas. Photodiodes usually have a slower response time as its surface area increases. The common, traditional solar cell used to generate electric solar power is a large area photodiode. Photodiodes and phototransistors look the same physically but have different functions.[2]
It is based on a reversed bias circuit.
Photodiode Media
IEEE 315-1975 (1993) 8.5.4.1
I-V characteristic of a photodiode. The linear load lines represent the response of the external circuit: I=(Applied bias voltage-Diode voltage)/Total resistance. The points of intersection with the curves represent the actual current and voltage for a given bias, resistance and illumination.
Electronic symbol for a phototransistor
Response of a silicon photo diode vs wavelength of the incident light
A one-dimensional photodiode array chip with more than 200 diodes in the line across the center
A two-dimensional photodiode array of only 4 × 4 pixels occupies the left side of the first optical mouse sensor chip, c. 1982.
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References
- ↑ International Union of Pure and Applied Chemistry. "Photodiode". Compendium of Chemical Terminology Internet edition.
- ↑ Cathleen Shamieh; Gordon McComb, Electronics For Dummies (Hoboken, NJ: Wiley Pub., 2009), p. 337
