Chemically and electronically active metal ions on InAs quantum dots for infrared detectors

Abstract

Colloidal InAs quantum dots (QDs) are emerging candidates for NIR-SWIR optoelectronic applications because of their excellent electrical and optical properties. However, the syntheses of InAs QDs, which demand strongly reducing atmospheres or highly reactive precursors, are difficult because of their highly covalent bonding and lack of Group 15 precursors. While the coreduction method with commercially available arsenic precursors enables facile syntheses of InAs QDs, it results in broad size distributions requiring subsequent size-selection processes. In this study, we introduced zinc ions in the form of coordination complexes during coreduction of the indium and arsenic precursors. The Zn ions chemically passivated the surfaces of the InAs QDs, narrowed the size distribution and removed surface defects. When the InAs QDs were integrated into infrared photodiodes as IR absorbers, the surface-attached Zn ions electrically modulated the energy level and carrier concentration. Infrared photodiodes with the InAs:Zn QD layers exhibited dark currents and photoresponses that were two orders of magnitude lower and approximately twice as fast, respectively, as those seen for bare InAs QDs.