(333b) Mercury Telluride Colloidal Quantum Dots for Mid-Wave IR Photodetection at Room Temperature

Mercury telluride (HgTe) nanocrystal-based infrared (IR) photodetectors provide a low-cost alternative to traditional mercury cadmium telluride (MCT) devices made through epitaxial growth methods. Since bulk HgTe is a semi-metal with a band gap of -0.3 eV, the size-tunable optoelectronic properties of HgTe quantum dots (QDs) provide for synthetic tuning of the optical absorption edge across the entire IR spectral region. However, there are practical challenges in obtaining the necessary HgTe nanocrystal stability and photoresponse for commercial applications. The typical growth temperatures used for semiconductor nanocrystals result in very broad size distributions and HgTe nanocrystals with poor colloidal stability and photoresponse. We have developed a multi-step synthesis of uniform, shape-anisotropic HgTe QDs that greatly enhances the photoconductive response of the materials, provides wide tuning of the optical cutoff and good device stability. Devices with room temperature mid-wave IR (MWIR) optical response cutoffs with wavelengths up to 5 mm can be achieved.