Conduction Band Resonant State Absorption for Quantum Dot Infrared Detectors Operating at Room Temperature

Abstract

Long wavelength infrared devices, despite growing interest due to a wide range of applications in commercial, public, and academic sectors, are still struggling to achieve significant improvements over well-established technologies like HgCdTe detectors. Devices based on quantum nanostructures remain non competitive due to unresolved drawbacks, the most significant being the need for cooling down to liquid nitrogen temperatures to improve the signal-to-noise ratio. In this work, we demonstrate an innovative solution to surpass the current generation of quantum dot-based detectors by exploiting absorption from quantum dot-localized states to resonant states in the continuum, that is, states in the semiconductor conduction band with an enhanced probability density in the quantum dot region. This unprecedented approach takes advantage of the unique properties of such states to massively enhance carrier extraction, overcoming one of the most crucial drawbacks of quantum dot-based infrared detectors. This innovative solution is discussed here from both theoretical and experimental perspectives. The measured room temperature operation demonstrates that exploiting resonant state absorption in quantum dots offers the long-sought solution for the next generation of infrared photodetectors.