Gallium antimonide infrared photodetector grown directly on silicon for first time

With numerous bandgap engineering possibilities, the gallium antimonide (GaSb) family of semiconductor crystals offer the potential to create myriad architectures for infrared photodetectors.

Researchers at the company IQE report a new technique that allows them to grow components of a GaSb-based infrared photodetector directly on large-diameter silicon substrates for the first time. Using a multi-step metamorphic buffer architecture process that included molecular beam epitaxy, Fastenau et al. grew a common mid-wave IR sensor architecture called a 4.2 µm nBn on the silicon wafer, and it was successfully fabricated into a working focal plane array (FPA).

Focal plane array infrared photodetectors have found a variety of uses, including thermal cameras, astronomical instruments, and medical imaging devices.

Growing directly on silicon provides a way to create larger GaSb-based focal plane arrays and taps into existing production methods for silicon chips, said Joel Fastenau, an author of the latest paper.

“Being able to grow the GaSb detector structure directly on a silicon wafer may improve or simplify the integration with read out circuity,” said Fastenau. “It may reduce production costs by eliminating the wafer-removal step in the focal plane array process.”

X-ray diffraction and photoluminescence measurements confirmed that the crystal was high quality. Further examinations showed that the device enjoyed no degradation in quantum efficiency, and the FPA produced high-resolution images.

The design of the group’s detector allows for wavelengths up to 4.2 micrometers. Fastenau said he looks to work on future detectors capable of 5 micrometers and longer and hopes the work encourages others to investigate growth paths for GaSb-based devices on silicon.

Source: “Direct MBE growth of metamorphic nBn infrared photodetectors on 150 mm Ge-Si substrates for heterogeneous integration,” by Joel M. Fastenau, Dmitri Lubyshev, Scott A. Nelson, Matthew Fetters, Hubert Krysiak, Joe Zeng, Michael Kattner, P. Frey, Amy W. K. Liu, Aled O. Morgan, Stuart A. Edwards, Richard Dennis, Kim Beech, Doug Burrows, Kelly Patnaude, Ross Faska, Jason Bundas, Axel Reisinger, and Mani Sundaram, Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures (2019). The article can be accessed at https://doi.org/10.1116/1.5088784 .