Design and Simulation of an Advanced Solid-state Photomultiplier for Fiber-Optic Communication Systems

Abstract

Detection of weak infrared light is essential for high data rate fiber-optic communication systems since its
performance depends heavily on the sensitivity and bandwidth of photodetectors. Semiconductor diodes are the
most common types of photodetectors that are widely considered. Indium Arsenide (InAs), being an Avalanche
Photodiode (APD), has become a solid-state photodetector of choice owing to its ability to detect infrared light of
up to about 3.5 μm. In this work, the depletion width and electric field profile of p-i-n InAs were simulated and
used to obtain the multiplication gain. The effect of combining a series of p-i-n InAs in order to obtain longer
depletion width for the purpose of achieving high multiplication gain was investigated. To achieve this main target,
the work was designed in two stages. The first stage involved designing a simple p-n junction of InAs to test the
model. Further improvement of the design to increase the depletion region was carried out by sand-witching an
intrinsic piece of semiconductor material between the p and n-regions to form p-i-n InAs. The results obtained
showed that the modification led to an interesting increase in the depletion width, electric field and the
multiplication gain. In the second stage, the series of p-i-n InAs were combined to form an “Advanced solid-state
photomultiplier”. For the first time, a larger depletion width was achieved and thus increased multiplication gain.
The results presented deduced that this novel design is promising since an appreciable gain much greater than 1000
was achieved at about 6 V. Therefore, this could be used as an alternative to photomultiplier tube as well as other
expensive photodetectors available.