Low dark current, planar In0.4Ga0.6As p-i-n photodiode prepared by molecular beam epitaxy growth on GaAs

We report here the successful fabrication of a planar, low dark current, and high sensitivity In0.4Ga0.6As p-i-n photodiode fabricated on a semi-insulating GaAs substrate with the aid of a multistage strain-relief buffer system. Without using surface passivation and anti-reflection coatings, the detector has a quantum efficiency of 42% and a peak responsivity of 0.45 A/W at 1.3 μm wavelength. The reverse leakage current for the mesa-etched photodiode with an active area of 2×10−4 cm2 is 5×10−9 A at −5 V, and the breakdown voltage exceeds 25 V.