Lead-Free Quantum Dot Photodiodes for Next Generation Short Wave Infrared Optical Sensors

Abstract

Colloidal quantum dot sensors are disrupting imaging beyond the spectral limits of silicon. In this paper, we present imagers based on InAs QDs as alternative for 1st generation Pb-based stacks. New synthesis method yields 9 nm QDs optimized for 1400 nm and solution-phase ligand exchange results in uniform 1-step coating. Initial EQE is 17.4% at 1390 nm on glass and 5.8% EQE on silicon (detectivity of 7.4×109 Jones). Using metal-oxide transport layers and>300 hour air-stability enable compatibility with fab manufacturing. These results are a starting point towards the 2nd generation quantum dot SWIR imagers.