Undoped InP sandwiched InGaAs p-i-n photodetector with partially p-doped photoabsorption layer grown on linearly graded metamorphic in_xGa _1-xP buffered GaAs substrate

A novel top-illuminated In0.53Ga0.47As p-i-n photodiodes, with the partially p-doped photoabsorption layer, grown on GaAs substrate by using a linearly graded metamorphic InxGa1-xP (x graded from 0.49 to 1) buffer layer is reported. The dark current, optical responsivities, noise equivalent power, and operational bandwidth of the MM-PINPD with aperture diameter of 60 μm are 13 pA, 0.6 A/W, 3.4⊕10^-15 W/Hz^1/2, and 8 GHz, respectively, at 1550 nm. Under the illumination of 1.2-ps pulse-train, the measured impulse response is 41 ps and the frequency bandwidth is up to 8 GHz with heterodyne beating measurement. The low cost InGaAs photodiode with high current bandwidth product (350 mA⊕GHz, at 10 GHz) and bandwidth-efficient product (4.8 GHz⊕A/W) have been achieved.