PIN diode

From Wikipedia, the free encyclopedia

PIN diode (p-type, intrinsic, n-type diode) is a diode with a wide, undoped intrinsic semiconductor region between p-type semiconductor and n-type semiconductor regions.

PIN diodes act as near perfect resistors at RF and microwave frequencies. The resistance is dependent on the DC current applied to the diode.

A PIN diode exhibits an increase in its electrical conductivity as a function of the intensity, wavelength, and modulation rate of the incident radiation.

The benefit of a PIN diode is that the depletion region exists almost completely within the intrinsic region, which is a constant width (or almost constant) regardless of the reverse bias applied to the diode. This intrinsic region can be made large, increasing the area where electron-hole pairs can be generated. For these reasons many photodetector devices include at least one PIN diode in their construction, for example PIN photodiodes and phototransistors (in which the base-collector junction is a PIN diode).

They are not limited in speed by the capacitance between n and p region anymore, but by the time the electrons need to drift across the undoped region.

[edit] Examples

SFH203 or BPW43 are cheap general purpose PIN diodes in 5 mm clear plastic case with bandwidth over 100 MHz. They are used in RONJA telecommunication systems. Other more specialized PIN diodes are used in fiber optic network cards and switches.