Optical properties of nanostructured TiO_2thin films and their application as antireflection coatings on infrared detectors

Abstract

Oblique-angle deposited titanium dioxide (TiO(2)) nanorods have attracted much attention as good antireflection (AR) coating material due to their low n profile. Therefore, it is necessary to better understand the optical properties of these nanorods. TiO(2) nanorods grown on glass and Si substrates were characterized in the visible (0.4-0.8 μm) and infrared (2-12 μm) regions to extract their complex n profiles empirically. Application of these nanorods in multilayer AR coatings on infrared detectors is also discussed. Optimization of graded index profile of these AR coatings in the broad infrared region (2-12 μm) even at oblique angles of incidence is discussed. The effective coupling between the incoming light and multiple nanorod layers for reducing the reflection is obtained by optimizing the effect from Fabry-Perot oscillations. An optimized five-layer AR coating on GaN shows the reflectance less than 3.3% for normal incidence and 10.5% at 60° across the whole 2-8 μm spectral range.

Label-free sensitivity of long-period gratings enhanced by atomic layer deposited TiO_2 nano-overlays

“…TiO 2 shows high temperature and high electrical resistance as well as high hardness, low optical absorption, and biocompatibility [16,17]. It has been used as an antireflection coating on infrared detectors [18], optical resonance filters [19] or as planar waveguiding structures [20]. It has been shown that when TiO 2 overlay is deposited on LPG with sol-gel method it adsorbs water molecules and can be applied for humidity sensing [21,22].…”

Fabrication and characterisation of TiO 2 anti‐reflection coatings with gradient index

“…Various structures including randomly or periodically textured surfaces, nanoparticle arrays and plasmonic nanostructures have been investigated both theoretically and experimentally [7][8][9][10]. Majorities of fabrication methods have been developed such as vapour-liquid-solid, solution-liquid-solid, metal-assisted chemical etching, nano-imprint lithography, oblique-angle deposition (OAD), atomic layer deposition (ALD) technique etc [9][10][11][12][13][14][15][16][17][18][19]. Xi et al fabricated five-layered graded-index films with TiO 2 /SiO 2 nanorods on aluminium nitride substrate by OAD at a vapour incident angle of 87° [11].…”

Thermal stability of Au–TiO2 nanocomposite films prepared by direct liquid injection CVD

“…Anatase titanium dioxide (TiO 2 ) thin films are chemically stable, possess a high refractive index and an excellent transmittance in the visible range [15][16]. Therefore, they are extensively used in photocatalytic [17][18] and optical applications [19][20].…”