High quantum efficiency, long wavelength InP/InGaAs microcavity photodiode

There is a inherent tradeoff between the quantum efficiency and bandwidth of conventional PIN photodiodes. In the case of devices based on III-V semiconductors, an absorption region thickness of approximately 2 mu m is required to achieve quantum efficiencies greater than 80%, although this limits the transit-time-limited bandwidth to less than 15 GHz. It has recently been shown that a microcavity photodiode can circumvent this performance tradeoff and achieve both high quantum efficiency and large bandwidths. The fabrication of a microcavity PIN photodiode with a high quantum efficiency near 1.55 mu m is described. An external quantum efficiency of 82% at 1480 nm has been achieved with an InGaAs absorption layer only 2000 AA thick embedded in a resonant cavity grown by metal organic vapor phase epitaxy (MOVPE).