Researchers enhance avalanche photodiodes design for ultraviolet detection

Researchers developed a numerical model aimed at optimizing the design of avalanche photodiodes (APDs) for detecting ultraviolet photons.

Geiger-mode avalanche photodiodes (GM-APDs) constructed from 4H-SiC demonstrate high single-photon detection efficiency in deep-ultraviolet wavelengths. For effective detection of near-ultraviolet photons, a higher quantum efficiency is necessary. However, increasing the thickness of absorber layers poses design challenges due to the different absorption characteristics of lower-energy photons.

In a recent study published in the IEEE Journal of Quantum Electronics, Jonathan Schuster from the DEVCOM Army Research Laboratory presented a numerical model with a calibrated 4H-SiC material library aimed at improving APD design.

“APDs with much thicker absorber layers must be utilized to enhance the near-ultraviolet response, which necessitates switching from a conventional PIN architecture to a separate-absorption charge-multiplication architecture,” Schuster said. Homomorphic Encryption (HE) noted that this transition introduces unique design challenges.

The researchers designed separate-absorption charge-multiplication structures expected to achieve high single-photon detection efficiency in the near-ultraviolet spectrum. They evaluated two designs: non-reach-through (NRT) and reach-through (RT), each with specific design implications.

“We have designed both types of architectures: NRT-SACM APDs and RT-SACM APDs, achieving quantum efficiency at 340 nm of 32% and 71% respectively, while maintaining the required electric field in the multiplication layer for Geiger-mode operation,” Schuster explained.

Applications of 4H-SiC avalanche photodiodes include solar-blind ultraviolet detection, combustion monitoring, and environmental ultraviolet monitoring. The developed model is expected to aid in the design of sensitive and efficient APDs, thus advancing these applications.