High-Speed Normal-Incidence p-i-n InGaAs Photodetectors Grown on Silicon Substrates by MOCVD

High-speed normal-incidence p-i-n InGaAs photodetectors epitaxially grown on silicon substrates by metal-organic chemical vapor deposition has been demonstrated. The InGaAs active layer lattice-matched to InP was successfully grown on Si substrates employing metamorphic growth of InP and GaAs buffers with a two-step growth technique, in addition to cyclic thermal annealing and strain-balancing layer stacks. Circular devices with diameters ranging from 20 to 60 mu m were fabricated. Dark current diminished and 3-dB bandwidth increased with a reduction of the device area. A dark current of 0.2 mu A and a responsivity of 0.5 A/W at 1550 nm were measured at -1 V for a device 20 mu m in diameter. This device exhibited an optical 3-dB bandwidth of 10 GHz at -5 V. An open eye diagram at 10 Gb/s at a low reverse bias of 1 V was also demonstrated.