A number of the physical properties of lithium niobate strongly depend on sample composition. Although several procedures for the determination of the composition have already been published, a critical survey and an introduction to standard methods recommendable also for laboratories active in R&D of LiNbO3 devices is still missing. Within a detailed description of a series of methods, we summarise their capabilities and accuracy. The proposed optical characterisation methods, in particular those based on the generation of second harmonic light and those involving the measurement of birefringence and the UV absorption edge are found to be most convenient for an accurate and fast standard characterisation of LiNbO3 single crystals. An absolute accuracy of 0.1 mol% based on a comparison with the Curie temperature calibration method and a relative accuracy of up to 0.01 mol% are available. Some of these methods are also suited for the two or three dimensional homogeneity control of LiNbO3 single crystals.

Optical methods to characterise the composition and homogeneity of lithium niobate single crystals

A previously reported multistep hot filament chemical vapor deposition process for nucleating diamond directly on nickel substrates has been further refined to increase the nucleation density and improve the orientation of diamond films. The process employed heavy seeding of both 〈100〉 and 〈111〉 oriented single crystal Ni surfaces with diamond powders to enhance the nucleation density of diamond films. The deposition conditions were adjusted to allow for 〈100〉 and 〈111〉 orientations to grow on similarly oriented substrates to form nearly complete films with grain boundaries being eliminated. Thus, the technique holds promise for developing heteroepitaxial diamond films for microelectronics applications.

Oriented diamond films grown on nickel substrates

The shift of the UV-absorption edge was applied to determine the real LiNbO3 crystal composition. The accuracy of the method is about 10−2 mole% using a simple commercial UV-spectrophotometer. The effect of various impurities and other error sources are discussed.

A simple method to determine the real composition of LiNbO3 crystals

Silicon-on-insulator by graphoepitaxy and zone-melting recrystallization of patterned films

Epitaxial formation support structures and associated methods of manufacturing epitaxial formation support structures and solid state lighting devices are disclosed herein. In several embodiments, a method of manufacturing an epitaxial formation support substrate can include forming an uncured support substrate that has a first side, a second side opposite the first side, and coefficient of thermal expansion substantially similar to N-type gallium nitride. The method can further include positioning the first side of the uncured support substrate on a first surface of a first reference plate and positioning a second surface of a second reference plate on the second side to form a stack. The first and second surfaces can include uniformly flat portions. The method can also include firing the stack to sinter the uncured support substrate. At least side of the support substrate can form a planar surface that is substantially uniformly flat.

Epitaxial formation support structures and associated methods

The artificial epitaxy (diataxy) of silicon and germanium on amorphous quartz substrates was investigated in order to determine the best type of relief pattern, the mechanism of orientation and other regularities of the process.

Artificial epitaxy /diataxy/ of silicon and germanium

LiNbO3 single crystals were grown from melt by Czochralski method, for acousto-electronic purposes. The stoichiometric problems in connection with growing were studied by chemical methods: gravimetric method, based on the determination of Nb in its NbO(Oxine)3 complex; volumetric method, involving titration of peroxo-niobium(V) complex; spectrophotometric determination, in form of peroxo-niobium(V) complex in its acidic solution at 340 nm. The properties of crystals were investigated by physical methods. The inclusions, strains were studied by different microscopic investigations.

Growth, stoichiometry and properties of LiNbO3 single crystals

The positions of crystals floating on the surface of a liquid in triangular and quadratic cells are investigated. It is demonstrated that the orientations of the crystals can be explained by capillary forces.

On the orientation effect of capillary forces

The equilibrium positions of aluminium plates of different shapes floating by capillary forces on water surface in glass cells of various forms are investigated. In the centre of the cells the floating plates have an equilibrium orientation for which the symmetry elements of the cell and those of the floating plate coincide with each other as far as possible.

Symmetrical configurations by capillary forces

The static and dynamic Young’s moduli, and the dynamic shear modulus of sodium chloride whiskers grown by various methods were measured at room temperature in the direction. In the thickness range of 2–18 μ no dependence on whisker dimension was detected. According to the experimental results the values of the elastic moduli measured correspond to values obtained with large single crystals.

E. Hartmann

Papers

Artificial epitaxy /diataxy/ of silicon and germanium

Growth, stoichiometry and properties of LiNbO3 single crystals

On the orientation effect of capillary forces

Symmetrical configurations by capillary forces

The Young’s and shear moduli of NaCl whiskers