Narrow bandgap silver mercury telluride alloy semiconductor nanocrystal for self-powered midwavelength-infrared photodiode

Infrared colloidal quantum dots (CQDs) have been of interest due to their low-cost fabrication and facile wavelength tunability for various infrared optoelectronic applications. Recently, the mid-wavelength infrared (MWIR) quantum dot sensor has been successfully realized by forming a photodiode via a post-chemical treatment method. Controlling the doping density of the quantum dot solid and engineering the device structure require an extremely sophisticated technique, which hinders consistent doping density and restricts further development in understanding the fundamental photophysics and manufacturing process. Here, we report an air-stable and highly reproducible MWIR CQDs photodiode by incorporating synthesized p-doped Ag-HgTe colloidal nanocrystals (NCs). The Ag-HgTe alloy NCs allow clearly defined p-doped QDs layers, leading to uniform dopant distribution and the ease of engineering device fabrication. By optimizing the doping density, we achieved an average noise equivalent temperature difference of below 10 mK at 78 K with the self-powered MWIR photodiode sensor. Infrared colloidal quantum dots are interesting due to their low-cost fabrication and wavelength tunability for optoelectronic applications. Here, air-stable low-noise mid-infrared photodiode devices are fabricated using hole-doped Ag-HgTe nanocrystals.