HgTe colloidal quantum dot tripods for infrared photodetection

Abstract

Mercury telluride (HgTe) nanocrystal quantum dot-based infrared photodetectors provide a low-cost alternative to mercury cadmium telluride (MCT) bulk alloy devices made through epitaxial growth methods. The size-tunable optical properties of HgTe colloidal quantum dots (CQDs) make it possible to synthetically target a range of absorption edge wavelengths encompassing the infrared region. In this work, we report the synthesis of HgTe CQDs with high aspect ratios using solution-based colloidal techniques. The radial diameter of the arms of tripodal HgTe CQDs can be adjusted between 3 and 7 nm, with corresponding decreases in aspect ratios (arm length/radial diameter) from six to two, respectively. Tripodal HgTe CQDs exhibit room temperature photoconductivity with optical response ranging from the short wavelength infrared (SWIR) to mid-wavelength infrared (MWIR) spectral region, with optical cutoffs increasing from 1.7 to 3.5 µm with increasing CQD arm diameter. These tripodal HgTe CQDs with high aspect ratios exhibit relatively strong photoconductivity response and are promising for CQD-based infrared photodetectors.