title: Surface passivation of a photonic crystal band-edge laser by atomic layer deposition of SiO2 and its application for biosensing.
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.
authors: Department of Biophysics and Chemical Biology, Seoul National University, Seoul 151-747, Republic of Korea. hsjeon@snu.ac.kr.
authors: Hyungrae
authors: H
authors: Cha
authors: Jeongkug
authors: J
authors: Lee
authors: Luke R
authors: LR
authors: Jordan
authors: Si Hoon
authors: SH
authors: Lee
authors: Sang-Hyun
authors: SH
authors: Oh
authors: Hyo Jin
authors: HJ
authors: Kim
authors: Juhun
authors: J
authors: Park
authors: Seunghun
authors: S
authors: Hong
authors: Heonsu
authors: H
authors: Jeon
mesh_terms: D015374:Biosensing Techniques; D001710:Biotin / Q000737:chemistry; D003460:Crystallization; D004867:Equipment Design; D007834:Lasers; D008027:Light; D049329:Nanostructures; D036103:Nanotechnology / Q000379:methods*; D055095:Optics and Photonics; D017785:Photons; D012031:Refractometry; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D019809:Streptavidin / Q000737:chemistry; D013499:Surface Properties; D014732:Vibration
chemical_list: D012821:Silanes; D001710:Biotin; D012822:Silicon Dioxide; D019809:Streptavidin