A Systematic Approach to High Operating Temperature (HOT) Colloidal Quantum Dot Infrared Photodetectors

In this Phase II proposal, our aim is to accelerate the development of a high operating temperature (HOT) state-of-the-art mid-wave infrared (MWIR) colloidal quantum dot (CQDs) based focal plane array for thermal imaging. In our Phase I effort, we developed an iterative, systematic approach to investigate the relationship between IR CQD synthesis, physical properties, device design, and device performance in a closed feedback loop. We demonstrated the feasibility of this approach by optimizing the HgTe CQD synthetic protocol to improve carrier mobilities and carrier lifetimes such that the quantum efficiency (QE) of a mid-wave infrared (MWIR) HgTe CQD photodiode was improved from 15% to 50% when operated at 80 K. For this Phase II, QDIR will apply the systematic approach developed in Phase I to the design and optimization of a low dark current heterojunction HgTe CQD-based photodetector capable of thermoelectrically-cooled (>200 K) performance with quantum efficiency (QE) of at least 50% in the MWIR spectral range. To achieve this goal, the systematic approach will be used to develop high quality HgTe CQDs and, in parallel, to engineer dark current blocking and carrier injection blocking HgTe CQD junctions to achieve a high sensitivity device. Finally, the HgTe CQD photodetectors will be monolithically integrated with commercial off the shelf large well capacity digital ROICs to demonstrate HOT MWIR thermal imaging that matches or exceeds conventional II-VI and III-V epitaxial imaging device capabilities.