Chemically and Electronically Active Metal Ions on InAs Quantum Dots for Infrared Detectors

AbstractColloidal InAs quantum dots (QDs) are emerging candidates for NIR-SWIR optoelectronic applications because of their excellent electrical and optical properties. However, the synthesis of InAs QDs, which demands a strongly reducing atmosphere or highly reactive precursors, is difficult because of their strong covalent bonding nature and lack of group 15 precursors. While the co-reduction method with commercially available arsenic precursors enables the facile synthesis of InAs QDs, it causes a broad size distribution, requiring a subsequent size-selection process. In this study, we introduce zinc metal ions in the form of a coordination complex during the co-reduction reaction of indium and arsenic precursors. Zn ions can chemically passivate the surface of InAs QDs, allowing the promotion of size focusing and removal of surface defects. When the InAs QDs are integrated into infrared photodiodes as IR absorbers, the surface-attached Zn ions can electrically modulate the energy level and carrier concentration. The infrared photodiodes with InAs:Zn QD layers exhibit two orders of magnitude lower dark current and about twice faster photo-response than those using bare InAs QDs.