Noise behaviour of InAlAs/GaInAs MSM photodetectors
Planar metal-semiconductor-metal (MSM) photodetectors are becoming increasingly popular for use in optoelectronic integrated circuits. A GalnAs absorption layer is used with a thin surface layer of a semiconductor and a higher Schottky barrier to limit the dark current for applications in the 1.3 – 1.6 μm fibre bands. Planar photodetectors are prone to lowfrequency noise because of traps at interfaces, and this may deteriorate the optical receiver performance. We have investigated the noise in low-leakage AlInAs/GaInAs detectors and find that the excess low frequency noise is limited to frequencies < 1 MHz under normal operating conditions.