Edge-illuminated refracting-facet photodiode with large bandwidth and highoutput voltage

A high-speed and high-output-voltage edge-illuminated refracting-facet phot odiode (REPD) has been developed by employing a thin absorption layer. In t he RFPD, the incident light parallel to the up-side surface is refracted at an inwardly angled facet and penetrates at a small angle in the absorption layer. The absorption length is thus effectively longer, resulting in high responsivity even at a thin absorption layer. In addition, since this RFPD uses a p-metal as a reflector, the absorption length is doubled. The light penetration at a small angle in the absorption layer also reduces the carr ier density, and thinning the absorption layer effectively suppresses the i nfluence of field modulation due to space charges. The fabricated RFPD has a responsivity as high as 0.69 A/W for 1.55 mu m light even with an absorpt ion layer as thin as 0.43 mu m, a maximum 3 dB bandwidth of 66 GHz, and a h igh output peak voltage of over 2.5 V.