Intraband cascade electroluminescence with weakly n-doped HgTe colloidal quantum dots.

This article focuses on demonstrating room-temperature intraband cascade electroluminescence (EL) near 6 μm wavelength using lightly n-doped mercury telluride (HgTe) colloidal quantum dots (CQDs) in metal–insulator–metal (MIM) devices. Films of HgTe CQDs with controlled doping and mobility were fabricated and characterized, showing EL emission centered at 1600 cm⁻¹ (6.25 μm) with external quantum efficiencies up to 4.4% when enhanced by gold nano-antennas. The study compares low- and high-mobility CQD films, finding that higher mobility enables much larger current densities but reduces EL efficiency, and presents a rate-equation model indicating that electrically driven population inversion and mid-infrared lasing could be achievable with optimized doping, mobility, and resonator structures. The work highlights the potential of HgTe CQDs for electrically pumped mid-infrared light sources and discusses the challenges and prospects for realizing CQD-based mid-infrared lasers.