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Issue 8, 2015
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Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing

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Abstract

We report on the conformal surface passivation of photonic crystal (PC) laser devices with an ultrathin dielectric layer. Air-bridge-type Γ-point band-edge lasers (BELs) are fabricated by forming a honeycomb lattice two-dimensional PC structure into an InGaAsP multiple-quantum-well epilayer. Atomic layer deposition (ALD) is employed for conformal deposition of a few-nanometer-thick SiO2 layer over the entire device surface, not only on the top and bottom surfaces of the air-bridge membrane but also on the air-hole sidewalls. Despite its extreme thinness, the ALD passivation layer is found to protect the InGaAsP BEL devices from harsh chemicals. In addition, the ALD-SiO2 is compatible with the silane-based surface chemistry, which allows us to use ALD-passivated BEL devices as label-free biosensors. The standard streptavidin–biotin interaction shifts the BEL lasing wavelength by ∼1 nm for the dipole-like Γ-point band-edge mode. A sharp lasing line (<0.2 nm, full width at half-maximum) and a large refractive index sensitivity (∼163 nm per RIU) produce a figure of merit as high as ∼800 for our BEL biosensor, which is at least an order of magnitude higher than those of more common biosensors that rely on a broad resonance peak, showing that our nanolaser structures are suitable for highly sensitive biosensor applications.

Graphical abstract: Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing

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Publication details

The article was received on 22 Dec 2014, accepted on 15 Jan 2015 and first published on 16 Jan 2015


Article type: Paper
DOI: 10.1039/C4NR07552H
Citation: Nanoscale, 2015,7, 3565-3571
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    Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing

    H. Cha, J. Lee, L. R. Jordan, S. H. Lee, S. Oh, H. J. Kim, J. Park, S. Hong and H. Jeon, Nanoscale, 2015, 7, 3565
    DOI: 10.1039/C4NR07552H

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