Spray-Stencil Lithography Enabled Large-Scale Fabrication of Multispectral Colloidal Quantum-Dot Infrared Detectors

Infrared HgTe colloidal quantum dots (CQDs) are attracting great interest due to their synthesis scalability, mechanical flexibility, wide spectrum tunability, and excellent photoelectric properties. However, traditional HgTe CQD infrared detector fabrication methods such as drop casting and spin coating cannot achieve spatial control of patterned CQD films, which limits their sensing range to just single waveband and greatly hinders the realization of pixelated or multispectral CQD detectors. In this paper, an efficient spray-stencil lithography technique is demonstrated for the scalable fabrication of multichannel HgTe CQD infrared detectors that can respond to different spectral ranges. Uniform and smooth CQD films can be deposited on rigid, flexible, and curved substrates up to 4 inch wafer. Both photoconductive and photovoltaic infrared HgTe CQD detectors are fabricated with peak D* above 10¹¹ Jones across short-wave and mid-wave regions and show infrared imaging with noise equivalent temperature difference down to 26.7 mK. Flexible multispectral detectors with six channels are fabricated by the proposed spray-stencil lithography method, and experimentally demonstrate spectral sensing and chemical analysis capability. It is believed that the proposed fabrication method provides a reliable scheme for the production of high-performance multispectral CQD infrared detector arrays.