Optical Losses in Ferroelectric Oxide Thin Films: Is There Light at the End of the Tunnel?

1994 ◽  
Vol 361 ◽  
Author(s):  
D. K. Fork ◽  
F. Armani-Leplingard ◽  
J. J. Kingston
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Optical Loss ◽  
Film Surface ◽  
Film Structure ◽  
Surface Scattering ◽  
Morphological Development ◽  
Optical Losses ◽  
Force Microscopy ◽  
Device Applications

ABSTRACTOptical losses are a barrier to use of ferroelectric waveguide thin films. Losses of about 2 dB/cm will reduce the efficiency of a frequency doubler by over 50%. Achieving losses on this order in conjunction with other essential film properties is difficult. The optical loss has several origins, including absorption, mode leakage, internal scattering and surface scattering. When the film surface morphology is accurately known, it is possible to estimate the surface scattering component of the loss. We have employed atomic force microscopy and computer modeling to compute, and correlate the optical loss as a function of film thickness and wavelength. The results suggest upper limits to the morphological roughness for various device applications. For lithium niobate films on sapphire which are intended to frequency double into the blue part of the spectrum, the optimal film thickness is about 400 nm and the RMS roughness is constrained below about 1.0 nm, with some weak dependence on grain size. Although present growth techniques do not appear to achieve this level of surface flatness intrinsically, an understanding of the morphological development of the film structure may lead to improvements.

scholarly journals Optical and Structural Properties of Thermally Evaporated Zinc Oxide Thin Films on Polyethylene Terephthalate Substrates

2011 ◽  
Vol 2011 ◽  
pp. 1-4 ◽  
Author(s):  
M. G. Faraj ◽  
K. Ibrahim
Keyword(s):  
Thin Films ◽  
Zinc Oxide ◽  
Film Thickness ◽  
Polyethylene Terephthalate ◽  
Film Surface ◽  
Root Mean Square Roughness ◽  
Oxide Thin Films ◽  
Transmission Method ◽  
Force Microscopy ◽  
Diffraction Patterns

Zinc oxide thin films of different thicknesses ranging from 100 to 300 nm were prepared on polyethylene terephthalate substrates with thermal evaporation in a vacuum of approximately3×10-5Torr. X-ray diffraction patterns confirm the proper phase formation of the material. From atomic force microscopy (AFM) images, it was found that the root mean square roughness of the film surface increased as the film thickness increased. The optical properties of ZnO on PET substrates were determined through the optical transmission method using an ultraviolet-visible spectrophotometer. The optical band gap values of ZnO thin films slightly decreased as the film thickness increased.

Surface Evolution of Copolymer thin Films as Revealed by Atomic Force Microscopy

1991 ◽  
Vol 248 ◽  
Author(s):  
G. Coulon ◽  
B. Collin ◽  
D. Chatenay ◽  
D. Ausserre
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Free Surface ◽  
Film Thickness ◽  
Early Stage ◽  
Film Surface ◽  
Spatial Correlations ◽  
Surface Evolution ◽  
Force Microscopy ◽  
Atomic Force

AbstractAtomic Force Microscopy has been used to study the early stage evolution of the free surface of annealed symmetric poly(styrene-b-n-butylmethacrylate) diblock copolymer thin films. As the lamellar ordering propagates through the film thickness, Islands or holes are formed on the free surface. It Is shown that, depending on the Initial film thickness, I.e. on the fraction of the film surface occupied by the islands (or holes) In the ordered state, the existence or non-existence of spatial correlations characterizes the ordering kinetics of both islands and holes. However, the limit between these two regimes is not the same in the two cases : in the case of holes, spatial correlations occur for a higher value of the surface coverage than In the case of islands.

scholarly journals Emergence and Evolution of Crystallization in TiO2 Thin Films: A Structural and Morphological Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1409
Author(s):  
Ofelia Durante ◽  
Cinzia Di Giorgio ◽  
Veronica Granata ◽  
Joshua Neilson ◽  
Rosalba Fittipaldi ◽  
...  
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Transition Metal Oxides ◽  
Annealing Temperature ◽  
Morphological Properties ◽  
Degree Of Crystallinity ◽  
Tio2 Thin Films ◽  
Force Microscopy ◽  
Heat Treated ◽  
Complementary Techniques

Among all transition metal oxides, titanium dioxide (TiO2) is one of the most intensively investigated materials due to its large range of applications, both in the amorphous and crystalline forms. We have produced amorphous TiO2 thin films by means of room temperature ion-plasma assisted e-beam deposition, and we have heat-treated the samples to study the onset of crystallization. Herein, we have detailed the earliest stage and the evolution of crystallization, as a function of both the annealing temperature, in the range 250–1000 °C, and the TiO2 thickness, varying between 5 and 200 nm. We have explored the structural and morphological properties of the as grown and heat-treated samples with Atomic Force Microscopy, Scanning Electron Microscopy, X-ray Diffractometry, and Raman spectroscopy. We have observed an increasing crystallization onset temperature as the film thickness is reduced, as well as remarkable differences in the crystallization evolution, depending on the film thickness. Moreover, we have shown a strong cross-talking among the complementary techniques used displaying that also surface imaging can provide distinctive information on material crystallization. Finally, we have also explored the phonon lifetime as a function of the TiO2 thickness and annealing temperature, both ultimately affecting the degree of crystallinity.

Preparation and Characterization of Magnetic Force Microscopy Tips Coated with Nickel Films by e-Beam Evaporation

2018 ◽  
Vol 765 ◽  
pp. 3-7
Author(s):  
Badin Damrongsak ◽  
Samutchar Coomkaew ◽  
Karnt Saengkaew ◽  
Ittipon Cheowanish ◽  
Pongsakorn Jantaratana
Keyword(s):  
Film Thickness ◽  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Film Surface ◽  
Electron Beam Evaporation ◽  
Film Stress ◽  
Nickel Films ◽  
Force Microscopy ◽  
Best Response ◽  
Cantilever Bending

In this work, magnetic force microscopy (MFM) tips coated with a nickel thin-film were prepared and characterized for applications in the measurement of the magnetic write field. Nickel films with various thicknesses in a range of 20 – 80 nm were deposited on silicon substrates and silicon atomic force microscopy (AFM) tips by electron beam evaporation. Film surface morphologies and magnetic properties of the coated nickel films were investigated by using AFM and vibrating sample magnetometry (VSM). The rms roughness increased with the film thickness and was in a range between 0.1 and 0.3 nm. VSM results revealed that the mean coercive field of the nickel films was 20 Oe and there was an increase in the coercivity as the film thickness increased. In addition, the prepared MFM tips were evaluated for the tip response to the dc and ac magnetic field generated from perpendicular write heads. It was found that the MFM tip had the best response to the write field when coated with 60 nm thick nickel film. The coating thickness over 60 nm was inapplicable due to the cantilever bending caused by the film stress.

Scanning Tunneling Microscopy and Atomic Force Microscopy Investigation of Organic Tetracyanoquinodimethane Thin Films

1997 ◽  
Vol 12 (8) ◽  
pp. 1942-1945 ◽  
Author(s):  
H. J. Gao ◽  
H. X. Zhang ◽  
Z. Q. Xue ◽  
S. J. Pang
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Scanning Tunneling Microscopy ◽  
Pyrolytic Graphite ◽  
Film Surface ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Investigation

Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) investigation of tetracyanoquinodimethane (TCNQ) and the related C60-TCNQ thin films is presented. Periodic molecular chains of the TCNQ on highly oriented pyrolytic graphite (HOPG) substrates were imaged, which demonstrated that the crystalline (001) plane was parallel to the substrate. For the C60-TCNQ thin films, we found that there were grains on the film surface. STM images within the grain revealed that the well-ordered rows and terraces, and the parallel rows in different grains were generally not in the same orientation. Moreover, the grain boundary was also observed. In addition, AFM was employed to modify the organic TCNQ film surface for the application of this type of materials to information recording and storage at the nanometer scale. The nanometer holes were successfully created on the TCNQ thin film by the AFM.

Optimization of p-type Nanocrystalline Silicon Thin Films for Solar Cells and Photodiodes

2009 ◽  
Vol 1153 ◽  
Author(s):  
Yuri Vygranenko ◽  
Ehsanollah Fathi ◽  
Andrei Sazonov ◽  
Manuela Vieira ◽  
Gregory Heiler ◽  
...  
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Chemical Vapor ◽  
Percolation Cluster ◽  
Nanocrystalline Silicon ◽  
Film Structure ◽  
Silicon Thin Films ◽  
Low Leakage ◽  
In Doping ◽  
P Type

AbstractWe report on structural, electronic, and optical properties of boron-doped, hydrogenated nanocrystalline silicon (nc-Si:H) thin films deposited by plasma-enhanced chemical vapor deposition (PECVD) at a substrate temperature of 150°C. Film properties were studied as a function of trimethylboron-to-silane ratio and film thickness. The film thickness was varied in the range from 14 to 100 nm. The conductivity of 60 nm thick films reached a peak value of 0.07 S/cm at a doping ratio of 1%. As a result of amorphization of the film structure, which was indicated by Raman spectra measurements, any further increase in doping reduced conductivity. We also observed an abrupt increase in conductivity with increasing film thickness ascribed to a percolation cluster composed of silicon nanocrystallites. The absorption loss of 25% at a wavelength of 400 nm was measured for the films with optimized conductivity deposited on glass and glass/ZnO:Al substrates. A low-leakage, blue-enhanced p-i-n photodiode with an nc-Si p-layer was also fabricated and characterized.

Growth Front Roughening of Room Temperature Deposited Oligomer Thin Films

2000 ◽  
Vol 648 ◽  
Author(s):  
D. Tsamouras ◽  
G. Palasantzas ◽  
J. Th. M. De Hosson ◽  
G. Hadziioannou
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Room Temperature ◽  
Growth Front ◽  
Silicon Substrates ◽  
Height Distribution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Roughness Amplitude ◽  
Non Gaussian

AbstractGrowth front scaling aspects are investigated for PPV-type oligomer thin films vapor- deposited onto silicon substrates at room temperature. For film thickness d~15-300 nm, commonly used in optoelectronic devices, correlation function measurement by atomic force microscopy yields roughness exponents in the range H=0.45±0.04, and an rms roughness amplitude which evolves with film thickness as a power law σ∝ dβ with β=0.28±0.05. The non-Gaussian height distribution and the measured scaling exponents (H and β) suggest a roughening mechanism close to that described by the Kardar-Parisi-Zhang scenario.

Morphology and Dielectric Properties of Reactively Sputtered Aluminum Nitride Thin Films

1996 ◽  
Vol 449 ◽  
Author(s):  
A. G. Randolph ◽  
S.K. Kurinec
Keyword(s):  
Thin Films ◽  
Aluminum Nitride ◽  
Dielectric Strength ◽  
Film Structure ◽  
Force Microscopy ◽  
Atomic Force ◽  
Anion Vacancies ◽  
Lossy Dielectrics ◽  
Auger Electron Spectroscopic Analysis ◽  
Microscopy Examination

ABSTRACTAluminum nitride thin films (∼ 100 mn) have been deposited on silicon substrate by reactive sputtering using Al target in 1:1 Ar:N2 environment. The atomic force microscopy examination revealed continuous microcrystalline film structure. The Auger electron spectroscopic analysis show the presence of oxygen in the films. The annealing at 850 C in nitrogen is found to cause recrystallization and further oxidation of the films. The films can be characterized as lossy dielectrics with relative permittivity ∼ 10, higher than the bulk value of 8.9. Annealing the films is found to reduce anion vacancies and improve the dielectric strength within a range of a few MV/cm in these thin films.

Microstructure and optical loss in epitaxial (Pb, La)TiO3 thin films on (001) MgO

1998 ◽  
Vol 13 (4) ◽  
pp. 995-1001 ◽  
Author(s):  
Young Min Kang ◽  
Sunggi Baik
Keyword(s):  
Thin Films ◽  
Smooth Surface ◽  
Optical Loss ◽  
Optical Losses ◽  
Coupling Technique ◽  
Optical Propagation ◽  
Domain Boundaries ◽  
Propagation Losses ◽  
La Substitution ◽  
Surface Morphologies

Surface morphologies and microstructures of epitaxial (Pb1−xLax)TiO3 (PLT, x = 0.00, 0.08, 0.16, and 0.24) thin films grown on (001) MgO have been investigated using SEM, AFM, and TEM. Surface roughness of PLT films varies severely with La concentration. For 0.08La-PLT film, very smooth surface has been achieved with 9.3 Å of RMS roughness. 0.00La- and 0.08La-PLT films show 90° domain structure, and periodic dimension of the domain is reduced by La substitution. 0.16La- and 0.24La-PLT films show the presence of triangular grains, causing rough surface and poor crystal quality. However, they are distributed uniformly in 0.16La-PLT film while agglomerated in 0.24La-PLT film. Optical propagation losses of PLT films measured by prism coupling technique were 22.3, 6.0, 11.4, and 20.7 dB/cm for x = 0.00, 0.08, 0.16, and 0.24, respectively. Such a variation in optical losses seemed to be due to the surface morphology and abundance of domain boundaries that change continuously as a function of La concentration in epitaxial PLT thin films.

scholarly journals Combined pulsed laser deposition and non-contact atomic force microscopy system for studies of insulator metal oxide thin films

2018 ◽  
Vol 9 ◽  
pp. 686-692 ◽  
Author(s):  
Daiki Katsube ◽  
Hayato Yamashita ◽  
Satoshi Abo ◽  
Masayuki Abe
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Metal Oxide ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Film Surface ◽  
Laser Deposition ◽  
Combined System ◽  
Force Microscopy ◽  
Atomic Force

We have designed and developed a combined system of pulsed laser deposition (PLD) and non-contact atomic force microscopy (NC-AFM) for observations of insulator metal oxide surfaces. With this system, the long-period iterations of sputtering and annealing used in conventional methods for preparing a metal oxide film surface are not required. The performance of the combined system is demonstrated for the preparation and high-resolution NC-AFM imaging of atomically flat thin films of anatase TiO2(001) and LaAlO3(100).

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