InGaAsP/InGaAs heterojunction p-i-n detectors with low dark current and small capacitance for 1.3—1.6 μm fibre optic systems

A new long wavelength p-i-n photodetector, consisting of an In0.53 Ga0.47 As absorbing layer and an adjacent InGaAsP p-n junction is demonstrated. These diodes exhibit dark currents as low as 0.2 nA and a capacitance < 0.5 pF at — 10 V for a device area of 1.3 × 10—4 cm2. The external quantum efficiency is — 60% at — = 1.3 —m for front illumination. A systematic study of the background doping of the quaternary layers using different InP sources is also reported.