Research team creates three colour photodetector

1 min read

While infrared waves are available in short, mid, and long lengths, most detection devices are unable to harness all three at the same time. However, Professor Manijeh Razeghi and her team, from Northwestern University, have developed a new approach in device design to create a three-colour, shortwave-midwave-longwave infrared photodetector.

The researchers say that by varying the applied bias voltage the device can detect different infrared wavebands. This could open up a range of potential applications, including infrared colour televisions and three-color infrared imaging.

Prof Razeghi explained: "A device capable of detecting different infrared wavebands is highly desirable in the next generation infrared imaging systems."

The researchers invented and investigated their design for three-colour photodiodes without using additional terminal contacts. The resulting photodetector is based on indium-arsenide/gallium-antimonide/aluminium-antimonide type-II superlattices.

As the applied bias voltage varies, the photodetector sequentially exhibits the behaviour of three different colours, corresponding to the bandgap of three absorbers, and is said to achieve well-defined cut-off wavelengths and high-quantum efficiency in each channel.

This research builds on the group's previous work in Northwestern's Centre for Quantum Devices, including the development of the first single-colour, short-wavelength infrared photodetector and two-colour, shortwave-midwave infrared photodetector based on type-II superlattices.

"I am fascinated by these results," Prof Razeghi said. "The initial success in this demonstration will drive us to the new frontier of infrared detection and imaging technology."