Abstract: An improved PIN photodiode provides enhanced linearity by confining the light absorption region of the diode wholly within the depletion region. The photodiode exhibits improved linearity over prior art designs because the thickness of the absorption region is no longer a function of changes in the size of the depletion region during device operation. Keeping the absorption region wholly within the depletion region ensures that the charge carriers generated by incident illumination will increase the conductivity of the semiconductor material.

Abstract: A PIN photodiode comprising a p region containing a p type dopant, an n region containing an n type dopant, an i region positioned intermediate the p region and the n region, and a relatively thick, undoped buffer region positioned between the n region and the i region which substantially decreases the capacitance of the PIN photodiode such that the photodiode bandwidth is maximized. Typically, the buffer region is formed as a layer of indium phosphide that is at least approximately 0.5 &mgr;m in thickness.

Abstract: An improved PIN photodiode provides enhanced linearity by confining the light absorption region of the diode wholly within the depletion region. The photodiode exhibits improved linearity over prior art designs because the thickness of the absorption region is no longer a function of changes in the size of the depletion region during device operation. Keeping the absorption region wholly within the depletion region ensures that the charge carriers generated by incident illumination will increase the conductivity of the semiconductor material.

Abstract: The invention is a photodetector device and a lightguide circuit incorporating the device. The photodetector device includes a semiconductor region for absorbing light which is incident on an edge surface of the device. The region above the absorbing region is narrow at the edge and fans out in the direction of light propagation in the device.