NEC Corporation in Japan Develops World’s First High-Sensitivity Uncooled Infrared Image Sensor Using High-Purity Semiconducting Carbon Nanotubes

NEC Corporation in Japan has recently succeeded in developing the world’s first high-sensitivity uncooled infrared image sensor using high-purity semiconducting carbon nanotubes in the infrared detection area. This achievement utilizes NEC’s proprietary extraction technology. NEC plans to commercialize this image sensor in 2025.

Infrared image sensors can convert infrared rays into electrical signals. They can detect infrared rays emitted from people and objects even in the dark. Therefore, infrared image sensors are widely used in various fields to provide safety support for social infrastructure, such as night vision to assist automobile driving in the dark, aircraft navigation systems, and security surveillance cameras.

Infrared image sensors can be divided into “cooled” and “uncooled” types. The cooled type operates at extremely low temperatures and has high sensitivity, but requires a large and expensive cooler, consumes a lot of electricity, and requires regular maintenance. On the other hand, the uncooled type can operate at near room temperature conditions, is small in size, low cost and consumes less power, but its sensitivity and resolution are inferior to the cooled type.

NEC discovered carbon nanotubes for the first time in the world in 1991 and has been a global leader in nanotechnology R&D. In 2018, NEC developed proprietary technology to extract only semiconducting carbon nanotubes at high purity from single-walled carbon nanotubes that contain a mixture of metallic and semiconducting types. NEC then discovered that thin films of semiconducting carbon nanotubes extracted with this technology have a large temperature coefficient of resistance near room temperature.

This newly developed infrared image sensor utilizes NEC’s proprietary technology and advantage in high temperature coefficient of semiconducting carbon nanotubes, achieving more than three times higher sensitivity than mainstream uncooled infrared image sensors using vanadium oxide or amorphous silicon.

By combining the thermal separation structure used in uncooled infrared image sensors, MEMS technology to realize this structure, and carbon nanotube printing and manufacturing technology cultivated over many years for printed transistors, NEC has succeeded in operating a high-resolution uncooled infrared image sensor with 640 x 480 pixels.

Part of this R&D was conducted in collaboration with Japan’s National Institute of Advanced Industrial Science and Technology (AIST). In addition, part of this achievement was supported by a security technology promotion program conducted by Japan’s Acquisition, Technology & Logistics Agency (ATLA).

Going forward, NEC will continue to develop infrared image sensor technologies and realize products and services that can contribute to various fields and areas of society.