CMOS-compatible germanium-tin on silicon could make inexpensive IR camera sensor

Researchers at the University of Arkansas (Fayetteville, AK) have fabricated a new form of semiconductor photodetecting material—germanium tin (GeSn) deposited in layers on a substrate of silicon (Si)—that could be used to build better and less expensive infrared cameras.¹

The structures were grown using commercially available chemical-vapor-deposition (CVD) equipment; the process is Si CMOS-compatible.

The researchers optically and electrically characterized GeSn photoconductors having a 0.9%, 3.2%, and 7.0% Sn content at temperatures from 77 K to room temperature. The maximum long-wavelength response to a 2.1 µm wavelength occurred for the device with the 7.0% Sn content.

Room temperature OK, cryogenic better

Cooling to cryogenic temperatures boosted the DC responsivity at 1.55 µm by around a factor of 100 for all Sn proportions.

"The performance of these simple structures indicates a promising future for germanium tin photodetectors," says Fisher Yu, associate professor of electrical engineering. "The crystalline growth of these samples in a commercially available reactor allows for these infrared detectors to be available for expedient commercial implementation."

Only a few other research groups are working with GeSn to produce semiconductor material for computer chips and electronics. The material has potential for other applications, including lasers and high-efficiency solar cells.

The research group is collaborating with ASM International, a private company that builds machine-epitaxy tools for fabricating microelectronics devices. The researchers have also started Arktonics (also in Fayetteville) to investigate future commercialization of GeSn materials and devices.

Source: https://newswire.uark.edu/articles/25202/germanium-tin-could-mean-better-and-cheaper-infrared-cameras-in-smartphones

REFERENCE:

1. Benjamin R. Conley et al., Optics Express (2014); http://dx.doi.org/10.1364/OE.22.015639