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SiGe Quantum Dots over Si Pillars for Visible to Near-infrared Broadband Photodetection

Research Area: Nanophotonics Year: 2013
Type of Publication: Article Keywords: nanopillar, nanowire, quantum dot, heteroepitaxy, growth, selective deposition, SiGe, photodetector
Authors: Wei-Ting Lai; P. Liao; Andrew Homyk; Axel Scherer; P. -W. Li
Journal: IEEE Photonics Technology Letters Volume: 25
Number: 15 Pages: 1520-1523
Month: August
We demonstrated a successful selective growth of Si0.3Ge0.7 quantum dots (QDs) over array of p+-Si nanopillars using low-pressure chemical vapor deposition technique, and hereafter realized high-performance QD broadband photodiodes for visible to near-infrared photodetection based on heterostructures of indium tin oxide/Si0.3Ge0.7 QD/Si pillar. Thanks to effective hole confinement and thus a built-in electric field within the SiGe QD, high ratios of photocurrent to dark current of ~2200, 100, and 30, respectively, were measured on our SiGe QDs-based photodiodes under illumination of 9 mW/cm2 at wavelength of 500−800, 1300, and 1500 nm. The QD photodiode exhibits a very low dark current density of 3.2×10-8 A/cm2 and a tunable power-dependent linearity by applied voltage through the competition of electron drift and carrier recombination processes.
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