摘要
High-sensitivity photodetection is at the heart of many optoelectronic applications,including spectroscopy,imaging,surveillance,remote sensing and medical diagnostics.Achieving the highest possible sensitivity for a given photodetector technology requires the development of ultra-small-footprint detectors,as the noise sources scale with the area of the detector.This must be accomplished while sacrificing neither the optically active area of the detector nor its responsivity.Currently,such designs are based on diffraction-limited approaches using optical lenses.Here,we employ a plasmonic flat-lens bull’s eye structure(BES)to concentrate and focus light into a nanoscale colloidal quantum dot(CQD)photodetector.The plasmonic lenses function as nanofocusing resonant structures that simultaneously offer color selectivity and enhanced sensitivity.Herein,we demonstrate the first CQD photodetector with a nanoscale footprint,the optically active area of which is determined by the BES;this detector represents an exciting opportunity for high-sensitivity sensing.
基金
We thank M Castro-Lo´pez for assistance with the transmission measurements,J Osmond and F Beck for assistance during clean-room fabrication,and M Lundeberg for wire bonding our samples.We acknowledge funding from the European Commission’s Seventh Framework Programme for Research under contract PIEF-GA-2011-298596 and from Fundacio Privada Cellex Barcelona.We are also grateful to the Ministerio de Ciencia e Innovacion for financial support under contract number TEC2011-24744.GK acknowledges MICINN for a Ramon y Cajal Fellowship.
