Researchers develop short-wave infrared technology to allow starlight detection

Prof Zhang Zhiyong’s team at Peking University developed a heterojunction-gated field-effect transistor (HGFET) that achieves high sensitivity in short-wave infrared detection, with a recorded specific detectivity above 10¹⁴ Jones at 1300 nm, making it capable of starlight detection. Their research was recently published in the journal Advanced Materials, titled “Opto-Electrical Decoupled Phototransistor for Starlight Detection.”

Highly sensitive shortwave infrared (SWIR) detectors are essential for detecting weak radiation (typically below 10⁻⁸ W·Sr⁻¹·cm⁻²·µm⁻¹) with high-end passive image sensors. However, mainstream SWIR detection based on epitaxial photodiodes cannot effectively detect ultraweak infrared radiation due to the lack of inherent gain.

Filling this gap, researchers at the Peking University School of Electronics and collaborators have presented a heterojunction-gated field-effect transistor (HGFET) that achieves ultra-high photogain and exceptionally low noise in the short-wavelength infrared (SWIR) region, benefiting from a design that incorporates a comprehensive opto-electric decoupling mechanism.

The team developed a HGFET consisting of a colloidal quantum dot (CQD)-based p-i-n heterojunction and a carbon nanotube (CNT) field-effect transistor, which significantly detects and amplifies SWIR signals with a high inherent gain while minimally amplifying noise, leading to a recorded specific detectivity above 10¹⁴ Jones at 1300 nm and a recorded maximum gain-bandwidth product of 69.2 THz.

Direct comparative testing indicates that the HGFET can detect weak infrared radiation at 0.46 nW cm⁻² levels, thus making this detector much more sensitive than the commercial and reported SWIR detectors, and especially enabling starlight detection or vision.