A SiC epitaxial wafer includes a SiC substrate and an epitaxial layer laminated on the SiC substrate, wherein the epitaxial layer contains an impurity element which determines the conductivity type of the epitaxial layer and boron which has a conductivity type different from the conductivity type of the impurity element, and the concentration of boron is less than 1.0×10.sup.14 cm.sup.−3 at any position in the plane of the epitaxial layer.

A SiC epitaxial wafer includes a SiC substrate and an epitaxial layer laminated on the SiC substrate, wherein the epitaxial layer contains an impurity element which determines the conductivity type of the epitaxial layer and boron which has a conductivity type different from the conductivity type of the impurity element, and the concentration of boron is less than 1.0×10.sup.14 cm.sup.−3 at any position in the plane of the epitaxial layer.

A control device has a learning model that outputs an estimated value of a second physical quantity that is unobservable under a condition of manufacturing a SiC crystal, from a first physical quantity that is observable under the condition of manufacturing the SiC crystal. The control device generates a basic learning model by mechanical learning using, as teacher data, a simulation result of a simulation model based on structural data of a SiC crystal manufacturing apparatus. The control device acquires measured values of the first physical quantity and the second physical quantity measured under a condition that the SiC crystal is unable to be manufactured while the second physical quantity is observable, and generates the learning model that corrects an output of the basic learning model based on the measured values.

A control device has a learning model that outputs an estimated value of a second physical quantity that is unobservable under a condition of manufacturing a SiC crystal, from a first physical quantity that is observable under the condition of manufacturing the SiC crystal. The control device generates a basic learning model by mechanical learning using, as teacher data, a simulation result of a simulation model based on structural data of a SiC crystal manufacturing apparatus. The control device acquires measured values of the first physical quantity and the second physical quantity measured under a condition that the SiC crystal is unable to be manufactured while the second physical quantity is observable, and generates the learning model that corrects an output of the basic learning model based on the measured values.

According to one embodiment, a scintillator includes a first layer provided on a surface of a substrate and including thallium activated cesium iodide; and a second layer provided on the first layer and including thallium activated cesium iodide. The second layer includes crystals having a [100] orientation partially diverted from a direction perpendicular to the surface of the substrate. Half width at half maximum of a frequency distribution curve of an angle between the direction perpendicular to the surface of the substrate and the [001] orientation, which is obtained by measuring the angle using EBSD method, is 2.4 degree or less.

According to one embodiment, a scintillator includes a first layer provided on a surface of a substrate and including thallium activated cesium iodide; and a second layer provided on the first layer and including thallium activated cesium iodide. The second layer includes crystals having a [100] orientation partially diverted from a direction perpendicular to the surface of the substrate. Half width at half maximum of a frequency distribution curve of an angle between the direction perpendicular to the surface of the substrate and the [001] orientation, which is obtained by measuring the angle using EBSD method, is 2.4 degree or less.

An apparatus includes a chemical vapor deposition (CVD) reactor, an injector column that provides a metal organic precursor vapor into the CVD reactor, a heater in thermal communication with the injector column, and a control circuit configured to control the heater and thereby maintain the metal organic precursor vapor in the injector column above a saturation temperature. The control circuit may be configured to control the heater to maintain a temperature of the metal organic precursor vapor in the injector column in a temperature range from about 85 degrees Centigrade to about 200 degrees Centigrade. A temperature of the metal organic precursor vapor entering the injector column may be in a range from about 160 degrees Centigrade to about 200 degrees Centigrade and a pressure of the metal organic precursor vapor entering the injector column may be in a range from about 50 mbar to about 1000 mbar.

An apparatus includes a chemical vapor deposition (CVD) reactor, an injector column that provides a metal organic precursor vapor into the CVD reactor, a heater in thermal communication with the injector column, and a control circuit configured to control the heater and thereby maintain the metal organic precursor vapor in the injector column above a saturation temperature. The control circuit may be configured to control the heater to maintain a temperature of the metal organic precursor vapor in the injector column in a temperature range from about 85 degrees Centigrade to about 200 degrees Centigrade. A temperature of the metal organic precursor vapor entering the injector column may be in a range from about 160 degrees Centigrade to about 200 degrees Centigrade and a pressure of the metal organic precursor vapor entering the injector column may be in a range from about 50 mbar to about 1000 mbar.

A wafer includes a buried substrate; a layer of silicon (100) disposed on the buried substrate and forming multiple U-shaped grooves, wherein each U-shaped groove comprises a bottom portion and silicon sidewalls (111) at an angle to the buried substrate; a buffer layer disposed within the multiple U-shaped grooves; and multiple gallium nitride (GaN)-based structures having vertical sidewalls disposed within and protruding above the multiple U-shaped grooves, the multiple GaN-based structures each including cubic gallium nitride (c-GaN) formed at merged growth fronts of hexagonal gallium nitride (h-GaN) that extend from the silicon sidewalls (111).

In an embodiment, an apparatus includes a first pyrometer and a second pyrometer configured to monitor thermal radiation from a first point and a second point on a backside of a wafer, respectively, a first heating source in a first region and a second heating source in a second region of an epitaxial growth chamber, respectively, where a first controller adjusts an output of the first heating source and the second heating source based upon the monitored thermal radiation from the first point and the second point, respectively, a third pyrometer and a fourth pyrometer configured to monitor thermal radiation from a third point and a fourth point on a frontside of the wafer, respectively, where a second controller adjusts a flow rate of one or more precursors injected into the epitaxial growth chamber based upon the monitored thermal radiation from the first, second, third, and fourth points.