In-Synthesis Se-Stabilization Enables Defect and Doping Engineering of HgTe Colloidal Quantum Dots.

Colloidal Quantum Dots (CQDs) of mercury telluride (HgTe) hold particular appeal for infrared photodetection due to their widely-tunable infrared absorption and good compatibility with Si electronics. While advances in surface chemistry have led to improved QD solids, the chemical stability of HgTe material has not been fully emphasized. In this study, we aimed to address this issue and identified a Se-stabilization strategy based on the surface coating of Se on HgTe CQDs via engineering in the precursor reactivity. The presence of Se-coating enables HgTe CQDs with improved colloidal stability, passivation and enhanced degree of freedom in doping tuning. This enables the construction of an optimized p-i-n HgTe CQDs infrared photodetectors with an ultra-low dark current 3.26 × 10-6 A/cm2 at -0.4 V and a room-temperature specific detectivity of 5.17 × 1011 Jones at a wavelength ∼2 um, approximately one order of magnitude improvement compared to that of the control device. The stabilizing effect of Se is well preserved in the thin film state, contributing to much improved device stability. The in-synthesis Se-stabilization strategy highlights the importance of the chemical stability of materials for the construction of semiconductor-grade CQD solids and might have important implications for other high-performance CQD optoelectronic devices. This article is protected by copyright. All rights reserved.