The team was from Cardiff University’s Institute for Compound Semiconductors (ICS) was led by Professor Diana Huffaker. It worked with collaborators from the University of Sheffield and the California NanoSystems Institute, University of California, Los Angeles (UCLA).
APDs are in demand for use in data communications and lidar for autonomous vehicles. Other compound semiconductor devices, typically InP and InAlAs are much used but their performance is limited by noise in high electric fields.
In paper published in Nature Photonics the authors report low excess noise in an AlAs0.56Sb0.44 lattice matched to InP. Computer modelling of performance in systems suggests that when vertically illuminated the APDs would have a sensitivity of -25.7dBm and that in communications applications a bit error rate of 1×10^-12 can be achieved with 1,550nm wavelength light at 25Gbps.
The APDs were made using molecular beam epitaxy (MBE) to “grow” the compound semiconductor crystal a layer at a time.
Professor Huffaker said: “Our work to develop extremely low excess noise and high sensitivity avalanche photodiodes has the potential to yield a new class of high-performance receivers for applications in networking and sensing.”
“The innovation lies in the advanced materials development using molecular beam epitaxy (MBE) to “grow” the compound semiconductor crystal in an atom-by-atom regime. This particular material is rather complex and challenging to synthesize as it combines four different atoms requiring a new MBE methodology. The Ser Cymru MBE facility is designed specifically to realize an entire family of challenging materials targeting future sensing solutions.”
Researcher Shiyu Xie, said: “The results we are reporting are significant as they operate in very low-signal environment, at room temperature, and very importantly are compatible with the current InP optoelectronic platform used by most commercial communication vendors.
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