Improved stability of HgTe quantum dot photodetectors through a CdTe hole transport layer

HgTe Colloidal Quantum Dots (CQDs) have garnered wide interests in the area of cost-effective infrared imaging technology. In this study, we developed a low-temperature drop-by-drop method to synthesize branched HgTe CQDs with well-defined bandtail states, resulting in enhanced excitonic absorption compared to conventional spherical quantum dots. By carefully adjusting the synthesis temperatures, we successfully obtained Short-Wave Infrared (SWIR) CQDs tunable within the range of 1.5 to approximately 3 μm. Furthermore, we improved the long-term stability of the photodetectors by incorporating CdTe nanocrystals, in place of the traditional Ag₂Te, as the Hole Transport Layer (HTL). As a result, our SWIR HgTe CQD photodetectors exhibited a room-temperature detectivity of 1.2 × 1011 Jones at the 1.7 μm cutoff absorption edge.