Mid-IR Narrow Bandgap Silver Mercury Telluride Alloy Semiconductor Nanocrystal for Self-powered Mid-IR Photodiode

Abstract

Abstract 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 CQD photodiode by incorporating newly synthesized p-doped Ag-HgTe nanocrystals (NCs). The Ag-HgTe alloy NCs allow clearly defined p-doped QD layers, leading to uniform dopant distribution and the ease of engineering device fabrication. By optimizing the doping density, we achieved a 3 mK noise equivalent temperature difference (NETD), the lowest value ever reported, at 78 K with the self-powered MWIR photodiode sensor.