Epitaxial Growth And Optical Properties of Sol-Gel (Pb,La)Ti03 Thin Films for Waveguides

1997 ◽  
Vol 474 ◽  
Author(s):  
Junmo Koo ◽  
Changho Lee ◽  
Kwangsoo No ◽  
Byeong-Soo Bae
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Refractive Index ◽  
Laser Light ◽  
Sol Gel ◽  
Surface Scattering ◽  
Sapphire Substrates ◽  
Lanthanum Titanate ◽  
Propagation Losses ◽  
Low Refractive Index

ABSTRACTLead lanthanum titanate thin films have been prepared on MgO and sapphire substrates by sol-gel method. XRD analyses confirm that the PLT films fabricated on MgO(lOO) and c-plane sapphire substrates grow preferentially with (100) and (111) orientations, respectively. The PLT films with a high La content have a low refractive index due to the decrease of the refractive index anisotropy. The propagation losses in PLT films measured, using He-Ne laser light and the prism coupling method decrease as the La content increases. This is due to the reduction of the refractive index anisotropy and the surface scattering by the surface roughness as a function of La content in the film.

The Influencing Factors for the Thickness of Silica Sol-Gel Film by the Dip Coating Process

2014 ◽  
Vol 597 ◽  
pp. 165-169
Author(s):  
Jie Hong Lei ◽  
Ri Dong Zhang
Keyword(s):  
Thin Films ◽  
Surface Roughness ◽  
Refractive Index ◽  
Sol Gel ◽  
Dip Coating ◽  
Silica Sol ◽  
Coating Process ◽  
Power Functions ◽  
Withdrawal Speed ◽  
Gel Film

The porous sol-gel silica thin films were prepared on silicon substrate by the dip coating process. The surface roughness and microstructure of the film was measured by optical microscopy and AFM .Coating thickness and refractive index were measured by ellipsometry method. Influence of withdrawal speed and concentration of colloid was investigated for the thickness of silica. The relation of the thickness and withdrawal speed was fitted by the linear and power functions, and the results were analyzed and compared. It was found that the films with the same thickness prepared by different concentrations of colloid have different refractive indexes. The experimental results indicated that the thickness and refractive index of the film can be controlled by changing the withdrawal speed and colloid concentration.

Optical Properties of Sol-Gel (Pb,La)TiO3 Thin Films For Waveguide Application

1995 ◽  
Vol 392 ◽  
Author(s):  
Byeong-Soo Bae ◽  
Won-Jong Lee ◽  
Kwang-Soo No ◽  
Dae-Sung Yoon ◽  
Sung-Uk Kim
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Optical Properties ◽  
Crystalline Phase ◽  
Sol Gel ◽  
Lanthanum Nitrate ◽  
Processing Conditions ◽  
Heating Condition ◽  
Glass Substrates ◽  
Lanthanum Titanate

AbstractLead lanthanum titanate ((Pb1−x/100Lax)Ti1−x/400O3, x=10, 20, 28) sol-gel thin films were prepared on SiO2/Si and glass substrates using lanthanum nitrate as a La precursor. The effect of the processing conditions was investigated and the optical properties of the films were measured to obtain good films for waveguide applications. The perovskite crystalline phase is achieved regardless of the heating condition but the slower heating creates better quality films. La content in the film does not effect on the refractive index and transparency of the film.

New Transparent Substrate with Silica Aerogel Film for Surface-Emissive Devices

2000 ◽  
Vol 660 ◽  
Author(s):  
H. Yokogawa ◽  
K. Kawano ◽  
M. Yokoyama ◽  
T. Tsutsui ◽  
M. Yahiro ◽  
...  
Keyword(s):  
Refractive Index ◽  
Glass Substrate ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Transparent Electrode ◽  
Light Sources ◽  
Photoluminescence Intensity ◽  
Transparent Substrate ◽  
Low Refractive Index

ABSTRACTSilica aerogels prepared by sol-gel methods with supercritical drying process have transparency and extremely low refractive index which is not available in any other materials. This extraordinary refractivity is expected to present some new features as an optical material. Ordinarily, coupling-out efficiency of surface-emissive light sources has been assumed to be low. It is due to the losses organized from internal reflection of emitted light at the air-glass interface and dissipation during wave-guiding propagation within the substrate.However, when material that has extremely low refractive index is inserted between a thin luminescence layer and glass substrate, almost all the light from the luminescence layer can efficiently couple out to air passing through the glass substrate. In this report, we introduce a silica aerogel film as a low refractive index material for surface-emissive devices, such as photoluminescent and electroluminescent device. In the experiments, the photoluminescence intensity of Alq3 through the silica aerogel layer was twice as large as that of the glass substrate without the silica aerogel film. Moreover, we formed a new substrate which contained a transparent electrode on the silica aerogel film. Using this substrate, we fabricated the OLED and observed the disappearance of wave-guiding propagation within the glass substrate.

scholarly journals Effect of Solution Conditions on the Properties of Sol–Gel Derived Potassium Sodium Niobate Thin Films on Platinized Sapphire Substrates

Nanomaterials ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1600 ◽  
Author(s):  
Alexander Tkach ◽  
André Santos ◽  
Sebastian Zlotnik ◽  
Ricardo Serrazina ◽  
Olena Okhay ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Low Cost ◽  
Sol Gel ◽  
Precursor Solution ◽  
Dissipation Factor ◽  
Solution Concentration ◽  
Potassium Sodium Niobate ◽  
Sapphire Substrates ◽  
Average Grain Size

If piezoelectric micro-devices based on K0.5Na0.5NbO3 (KNN) thin films are to achieve commercialization, it is critical to optimize the films’ performance using low-cost scalable processing conditions. Here, sol–gel derived KNN thin films are deposited using 0.2 and 0.4 M precursor solutions with 5% solely potassium excess and 20% alkali (both potassium and sodium) excess on platinized sapphire substrates with reduced thermal expansion mismatch in relation to KNN. Being then rapid thermal annealed at 750 °C for 5 min, the films revealed an identical thickness of ~340 nm but different properties. An average grain size of ~100 nm and nearly stoichiometric KNN films are obtained when using 5% potassium excess solution, while 20% alkali excess solutions give the grain size of 500–600 nm and (Na + K)/Nb ratio of 1.07–1.08 in the prepared films. Moreover, the 5% potassium excess solution films have a perovskite structure without clear preferential orientation, whereas a (100) texture appears for 20% alkali excess solutions, being particularly strong for the 0.4 M solution concentration. As a result of the grain size and (100) texturing competition, the highest room-temperature dielectric permittivity and lowest dissipation factor measured in the parallel-plate-capacitor geometry were obtained for KNN films using 0.2 M precursor solutions with 20% alkali excess. These films were also shown to possess more quadratic-like and less coercive local piezoelectric loops, compared to those from 5% potassium excess solution. Furthermore, KNN films with large (100)-textured grains prepared from 0.4 M precursor solution with 20% alkali excess were found to possess superior local piezoresponse attributed to multiscale domain microstructures.

Microstructural Evolution of Epitaxial LiNbO3 Thin Films Derived From Metal Alkoxide Solutions

1990 ◽  
Vol 202 ◽  
Author(s):  
Keiichi Nashimoto ◽  
Michael J. Cima ◽  
Wendell E. Rhine
Keyword(s):  
Thin Films ◽  
Grain Growth ◽  
Single Phase ◽  
Sol Gel ◽  
Precursor Solution ◽  
Epitaxial Films ◽  
Metal Alkoxide ◽  
High Annealing Temperature ◽  
Sapphire Substrates ◽  
High Annealing

ABSTRACTThe evolution of the microstructure of sol-gel derived LiNbO3 thin films was investigated to understand the growth of epitaxial films. LiNbO3 films were prepared from a precursor solution of lithium ethoxide and niobium pentaethoxide. Prehydrolysis promoted the development of polycrys-talline LiNbO3 films, whereas nonhydrolysis produced solid-state epitaxial growth of LiNbO3 films on sapphire substrates. Although the films looked smooth after annealing at 400°C, the morphology of the films changed, depending on substrates and precursors, due to grain growth at high annealing temperature. Prehydrolysis of the alkoxides caused a decrease in the temperature at which grain growth occurred, whereas the film prepared from the nonhydrolyzed precursor on a sapphire substrate showed denser texture and contained abnormally large domains that appeared to be single phase.

scholarly journals Study of TiO2, SnO2 and nanocomposites TiO2:SnO2 thin films prepared by sol-gel method: Successful elaboration of variable–refractive index systems

2020 ◽  
Vol 7 (1) ◽  
pp. 016439 ◽  
Author(s):  
F Medjaldi ◽  
A Bouabellou ◽  
Y Bouachiba ◽  
A Taabouche ◽  
K Bouatia ◽  
...  
Keyword(s):  
Thin Films ◽  
Refractive Index ◽  
Sol Gel ◽  
Gel Method ◽  
Sol Gel Method ◽  
Sno2 Thin Films ◽  
Index Systems
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