Megapixel large-format colloidal quantum-dot infrared imagers with resonant-cavity enhanced photoresponse

Abstract

Infrared imaging is extensively explored due to its unique properties of high atmospheric transmission and temperature-dependent emission. Unfortunately, the current epitaxial infrared materials suffer from a complicated fabrication process and low production yield, which hinders the further development of infrared imaging for civilian applications. As an alternative to epitaxial semiconductors, the wide spectral tunability and optical versatility of colloidal quantum dots (CQDs) have provided a promising route for infrared detection. Here, we demonstrate an infrared imager that integrates HgTe CQDs with complementary metal-oxide-semiconductor (CMOS) readout integrated circuits. Moreover, the underlying metal contacts and passivation layer of the CMOS chip play a role as an in-pixel resonant-cavity , which enhances the absorption of the CQDs film. The CQDs imager exhibits a detectivity of 2.8 × 1010 Jones, an external quantum efficiency of 14%, and an operable pixel factor of over 99.99% for a cut-off wavelength of around 2 µm at room-temperature. With a large-format (1280 × 1024 pixels2) and a small pixel pitch of 15 µm, the resolution of the imager can reach 40 line pairs per millimeter (lp/mm). The performance of the CQDs imager is demonstrated by infrared imaging.