A laser system includes a nonlinear optical (NLO) crystal, wherein the NLO crystal is annealed within a selected temperature range. The NLO crystal is passivated with at least one of hydrogen, deuterium, a hydrogen-containing compound or a deuterium-containing compound to a selected passivation level. The system further includes at least one light source, wherein at least one light source is configured to generate light of a selected wavelength and at least one light source is configured to transmit light through the NLO crystal. The system further includes a crystal housing unit configured to house the NLO crystal.

A method of analysing crystals is described. The method comprises focusing a laser into a crystal to induce the creation, modification, dissociation, or diffusion of one or more defects within a focal region of the laser. A signal dependent on the creation, modification, dissociation or diffusion of the one or more defects within the focal region of the laser is measured during or after the aforementioned process and used to determine one or more characteristics of the crystal being analysed. In one configuration, one or more fluorescent defects are created, modified, or dissociated and the fluorescent signal is analysed to determine the type of crystal being analysed.

Stack fault inspection apparatus and method are disclosed. The apparatus includes a sample stage fixing the silicon carbide substrate and allow the incident light to scan the substrate surface; an incident light source configured to irradiate a vertical illumination light of a wavelength corresponding to an energy greater than a band gap energy of the substrate to at least a portion of a surface of the substrate in a direction substantially perpendicular to the surface of the substrate; a photomultiplier tube (PMT) configured to obtain a photoluminescence mapping image having a wavelength corresponding to the band gap energy of the substrate from the surface of the substrate; and a controller configured to process the mapping image and identify stacking faults.

A SiC epitaxial wafer including a high-concentration epitaxial layer having an impurity concentration of 1×10.sup.18 cm.sup.−3 or more, and the number or positions of basal plane dislocations included in the high-concentration epitaxial layer have been identified

There is provided a nitride crystal substrate constituted by group-III nitride crystal, containing n-type impurities, with an absorption coefficient α being approximately expressed by equation (1) by a least squares method in a wavelength range of at least 1 μm or more and 3.3 μm or less.
α=N.sub.eKλ.sup.a  (1)
(where 1.5×10.sup.−19≤K≤6.0×10.sup.−19, a=3), here, a wavelength is λ (μm), an absorption coefficient of the nitride crystal substrate at 27° C. is α (cm.sup.−1), a carrier concentration in the nitride crystal substrate is N.sub.e (cm.sup.−3), and K and a are constants, wherein an error of an actually measured absorption coefficient with respect to the absorption coefficient α obtained from equation (1) at a wavelength of 2 μm is within ±0.1α, and in a reflection spectrum measured by irradiating the nitride crystal substrate with infrared light, there is no peak with a peak top within a wavenumber range of 1,200 cm.sup.−1 or more and 1,500 cm.sup.−1 or less.

The present application provides a method for characterizing defects in silicon crystal comprising the following steps: etching a surface of the silicon crystal to remove a predicted thickness of the silicon crystal; conducting a LLS scanning to a surface of the etched silicon crystal to obtain a LLS map of the surface, a LSE size of defects, and defect bulk density; based on at least one of the LLS map of the surface, the LSE size of defects and the defect bulk density, determining a type of defect existing in the silicon crystal and/or a defect zone of each type of defect on the surface. By applying the method, the characterizing period and the characterizing cost can be reduced, plural defects such as vacancy, oxygen precipitate and dislocation can be characterized simultaneously, the characterizing accuracy can be enhanced, and the defect type and the defect zone can be determined with high reliability. In addition, the method can be applied to all crystal defect types, is easy to operate, and is an environmentally friendly method for determination of grown-in defects.

Liquid crystal-based devices for detecting a target contaminant in air, including hydrogen, nitrogen dioxide, ozone, ammonia or carbon monoxide, and methods of using such devices to detect the target contaminant are disclosed. Such devices have a substrate surface that includes one or more metals or metal alloys that is in contact with a liquid crystal composition. When the device is contacted with a sample that contains the target contaminant, an observed change in the orientational ordering of the liquid crystal signals the presence of the target contaminant. In the absence of the target contaminant, no change in orientational ordering occurs.

The invention relates to methods for creating and detecting images inside diamonds that carry information for various purposes, for example, an identification code, marks identifying diamonds. A method for creating an optically permeable image inside a diamond is disclosed, in which image consists of a given set of optically permeable elements of micron or submicron size, which elements are disturbances in the periodicity of the diamond crystal structure. The image created in the diamond is a mark consisting of the given set of optically permeable elements of micron or submicron size. The elements are disturbances in the periodicity of the diamond crystal structure with the participation of chemical elements of impurities formed at vacancies and interstitials in the volume of micron or submicron size. Methods and systems for detecting optically permeable images inside diamonds are also disclosed.

Disclosed is a method for estimating twin defect density in a single-crystal sample, including: (A) etching the observed surface of a single crystal to form etch pits; (B) selecting bar-shaped etch pits caused by twin defect; (C) from the long-axis direction lengths of the etch pits caused by twin defect, estimating the twin defect density by using the following equation: twin defect density=Σkx′.sub.i/area of sample, wherein 2≤k≤3, and x′.sub.i is the long-axis direction length of an etch pit caused by the i-th twin.

A method of analysing a component formed from a metal alloy to identify a possible defect, wherein the metal alloy comprises a first crystal grain region and the possible defect comprises a second crystal grain region aligned to a different axis to the first crystal grain region, the method comprising the steps of: obtaining a first image of the component illuminated using a first polarisation state of light, the first image comprising first polarisation data; obtaining a second image of the component illuminated using a second polarisation state of light different to the first polarisation state, the second image comprising second polarisation data; determining a difference in polarisation data for plural pixels of the first image between each pixel of the first image and a corresponding pixel of the second image; and identifying pixels corresponding to the second crystal grain region based on the difference in polarisation data.