The Growth of Optical Quality LiNbo3 Thin Films On Sapphire and LiTao3 Substrates Using Solid-Source Mocvd

1995 ◽  
Vol 392 ◽  
Author(s):  
S. Y. Lee ◽  
R. K. Route ◽  
R. S. Feigelson
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Lithium Niobate ◽  
Growth Conditions ◽  
Substrate Material ◽  
Optical Quality ◽  
Epitaxial Thin Films ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Optical Waveguiding

AbstractHigh quality lithium niobate (LiNbO3) epitaxial thin films have been grown on c-plane sapphire and LiTaO3 substrates by solid-source MOCVD using the tetramethyl-heptanedionate sources, Li(thd) and Nb(thd)4. Phase content was controllable, and stoichiometric films were reproducibly deposited over a broad temperature range from a Li(thd)-rich source. Using sapphire substrates, with which the occurrence of multiple in-plane orientations is typically a problem, LiNbO3 films with only one in-plane orientation could be prepared within a narrow range of growth conditions. XRD rocking curve FWHM values as low as 0.04°, and optical waveguiding losses near 2dB/cm (1200Å thick film, TMo mode, 632.8nm) were obtained. However, film thicknesses on sapphire were limited to 2000Å because of cracking caused by the large thermal expansion mismatch, and in such thin films, optical confinement is poor.In contrast, LiTaO3 has almost same lattice constants and thermal expansion coefficients as LiNbO3, making it a potentially superior substrate material. Lithium niobate films up to 6000Å were successfully deposited on LiTaO3 substrates without cracking. Film quality was greatly improved, with FWHM values as low as 0.01°, and rms surface roughness less than 10 Å. Preliminary optical waveguiding losses less than 6 dB/cm for the TEo mode have been achieved.

Thermal expansion of the new perovskite substrates DyScO3 and GdScO3

2005 ◽  
Vol 20 (4) ◽  
pp. 952-958 ◽  
Author(s):  
M.D. Biegalski ◽  
J.H. Haeni ◽  
S. Trolier-McKinstry ◽  
D.G. Schlom ◽  
C.D. Brandle ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Rare Earth ◽  
Lattice Spacing ◽  
Epitaxial Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Increasing Temperature

The thermal expansion coefficients of DyScO3 and GdScO3 were determined from298 to 1273 K using x-ray diffraction. The average thermal expansion coefficients of DyScO3 and GdScO3 were 8.4 and 10.9 ppm/K, respectively. No phase transitions were detected over this range, though the orthorhombicity decreased with increasing temperature. These thermal expansion coefficients are similar to other oxide perovskites (e.g., BaTiO3 or SrTiO3), making these rare-earth scandates promising substrates for the growth of epitaxial thin films of many oxide perovskites that have similar lattice spacing and thermal expansion coefficients.

Defects in β-SiC thin films grown on α-SiC substrates

1988 ◽  
Vol 46 ◽  
pp. 568-569
Author(s):  
Karren L. More
Keyword(s):  
Thin Films ◽  
Semiconductor Device ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Substrate Material ◽  
Growth Interface ◽  
Si Substrates ◽  
Thermal Expansion Coefficients ◽  
Device Applications ◽  
Expansion Coefficients

Beta-SiC is an ideal candidate material for use in semiconductor device applications. Currently, monocrystalline β-SiC thin films are epitaxially grown on {100} Si substrates by chemical vapor deposition (CVD). These films, however, contain a high density of defects such as stacking faults, microtwins, and antiphase boundaries (APBs) as a result of the 20% lattice mismatch across the growth interface and an 8% difference in thermal expansion coefficients between Si and SiC. An ideal substrate material for the growth of β-SiC is α-SiC. Unfortunately, high purity, bulk α-SiC single crystals are very difficult to grow. The major source of SiC suitable for use as a substrate material is the random growth of {0001} 6H α-SiC crystals in an Acheson furnace used to make SiC grit for abrasive applications. To prepare clean, atomically smooth surfaces, the substrates are oxidized at 1473 K in flowing 02 for 1.5 h which removes ∽50 nm of the as-grown surface. The natural {0001} surface can terminate as either a Si (0001) layer or as a C (0001) layer.

Organo-Soluble, Segmented Rigid-Rod Polyimides: Synthesis and Properties

1991 ◽  
Vol 227 ◽  
Author(s):  
F. W. Harris ◽  
S. L. C. Hsu ◽  
C. J. Lee ◽  
B. S. Lee ◽  
F. Arnold ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
Glass Transition ◽  
Oxidative Stability ◽  
Organic Solvents ◽  
Dielectric Constants ◽  
Glass Transition Temperatures ◽  
Thermal Expansion Coefficients ◽  
Rigid Rod ◽  
Expansion Coefficients

ABSTRACTSeveral segmented, rigid-rod polyimides have been prepared that are soluble in organic solvents in their fully imidized form. The polymers were prepared from commercial dianhydrides and 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (TFMB). Their intrinsic viscosities ranged from 1.0 to 4.9 dL/g. Tough, colorless films could be cast from m-cresol solutions at 100°C. The polymers had glass transition temperatures (Tgs) above 275°C and displayed outstanding thermal and thermo-oxidative stability. Fibers were prepared from the 3,3′,4,4′-tetracarboxybiphenyl dianhydride (BPDA) based polymers that had moduli of 130 GPa and tensile strengths of 3.2 GPa. The thermal expansion coefficients and dielectric constants of thin films (20–25 μm) of the polymers were as low as −2.40×10−6 and 2.5, respectively.

Variations of lattice constants and thermal expansion coefficients of indium at high pressure and high temperature

2018 ◽  
Vol 38 (4) ◽  
pp. 406-413 ◽  
Author(s):  
Yusaku Takubo ◽  
Hidenori Terasaki ◽  
Tadashi Kondo ◽  
Shingo Mitai ◽  
Seiji Kamada ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermal Expansion ◽  
High Temperature ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients

Crystal Distortion Associated with Magnetic Ordering in Alpha Iron Oxide and Manganese Carbonate

1972 ◽  
Vol 16 ◽  
pp. 390-395 ◽  
Author(s):  
W. S. McCain ◽  
D. L. Albright
Keyword(s):  
Thermal Expansion ◽  
Lattice Constant ◽  
Room Temperature ◽  
Axial Ratio ◽  
Manganese Carbonate ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Position Parameter ◽  
Oxygen Distance

AbstractThe magnetic crystal disrortion of weakly ferromagnetic α-Fe2O3 was investigated by x-ray diffraction techniques. Here crystal distortion is taken as the temperature dependent changes of lattice constants and thermal expansion coefficients. Moreover, the oxygen position parameter and the carbon-oxygen distance of MnCO3 were determined.The lattice constants and thermal expansion coefficients of α-Fe2O3 were measured from room temperature down to 243°K. The crystal distortion, as measured by the changes in lattice constants, thermal expansion coefficients and axial ratio, was found to be highly anisotropic. The co hexagonal lattice constant was influenced very slightly by magnetic distortion; it changed only by 0.01 percent between room temperature and the Morin temperature of 254°K. On the other hand, the ao lattice constant changes by 0.11 percent between room temperature and the Morin temperature. The thermal expansion coefficients of the lattice constants showed a similar contrast. The co coefficient was found to be independent of temperature from room temperature down to the Morin temperature. However, in the same temperature range, the ao coefficient showed an anomalous increase with decreasing temperature. In addition, the ao coefficient showed an infinite discontinuity at the Morin temperature.The change in the axial ratio with temperature suggests that the net weak ferromagnetic moment of α-Fe2O3 reaches a maximum at 275°K.The oxygen position parameter, x, in MnCO3 as determined from two reflections has a value of 0.2702 ± 0.001. The carbon-oxygen distance as calculated from the lattice constants and the oxygen position parameter is 1.29 ±0.002 Å. This value is another confirmation of the Pauling theory of the resonating carbonate structure.

Epitaxial Ferroelectric Oxides for Electro-Optic and Non-Linear Optical Applications

1997 ◽  
Vol 495 ◽  
Author(s):  
B. W. Wessels
Keyword(s):  
Thin Films ◽  
Chemical Vapor ◽  
Optical Quality ◽  
Guided Wave ◽  
Epitaxial Thin Films ◽  
Electro Optic ◽  
Non Linear ◽  
Linear Optical ◽  
Optical Applications ◽  
Ferroelectric Oxides

ABSTRACTFerroelectric oxide epitaxial thin films are potentially important for a variety of guided-wave electro-optic and non-linear optical applications. Metalorganic chemical vapor deposition has been used to synthesize epitaxial thin films of a number of ferroelectric oxides. The films now have sufficient optical quality to enable the fabrication of waveguide devices including electro-optic modulators and optical amplifiers for 1.54 microns.

scholarly journals High temperature ferromagnetic ordering in c-axis oriented ZnO:Mn nanoparticle thin films by tailoring substrate temperature

2014 ◽  
Vol 32 ◽  
pp. 1460341 ◽  
Author(s):  
Usman Ilyas ◽  
P. Lee ◽  
T. L. Tan ◽  
R. V. Ramanujan ◽  
Sam Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Substrate Temperature ◽  
Magnetic Measurements ◽  
Deep Level ◽  
Growth Conditions ◽  
Optical Quality ◽  
Host Matrix ◽  
X Ray ◽  
Ferromagnetic Ordering ◽  
Substrate Temperatures

This study reports the enhanced ferromagnetic ordering in ZnO:Mn nanoparticle thin films, grown at different substrate temperatures using pulsed laser deposition. The optimum growth conditions were deduced from X-ray, photoemission and magnetic measurements. The X-ray measurements reveal that there was an optimum substrate temperature where the thin films showed relatively stronger texture, better crystallinity and lower strain. Substrate temperature tuned the deep level recombination centers in ZnO:Mn , which changed the optical quality by altering the electronic structure. The M-H curves, in the present study, revealed superior ferromagnetic response of 20-nm sized particles in ZnO:Mn thin film grown at a substrate temperature of 450 °C. Ferromagnetic ordering becomes weaker at higher/lower substrate temperatures due to the activation of native defects in ZnO host matrix.

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