InP/InGaAs pin photodiode structure maximising bandwidth and efficiency

A new photodiode design that combines depleted and neutral absorption layers to minimise carrier travelling delay time for a given total absorption layer thickness is proposed. The fabricated photodiode has a thick (0.8 pm) InGaAs absorption layer and achieves a responsivity of 0.98 A/W at lambda = 1.55 mum while still maintaining a high bandwidth of 50 GHz.