Enhancement of the bandwidth of p-i-n photodiodes by utilizing tandem structures

We propose a new method of increasing the maximum 3dB-bandwidth of InGaAs/InP p-i-n photodiodes for optical communication applications. It is demonstrated by calculation that employing tandem structures (p-i-n)N (N ≥ 2) enhances the maximum 3dB-bandwidth by a factor of √N after optimizing the i-layer thickness for the side illumination case, although the photosensitivity decreases by a factor of N. Conditions imposed on the i-layer thickness for complete carrier recombination in the intermediate n-p junctions are derived.