A process produces a single crystal of silicon. The process includes: installing a feed rod in a float-zone apparatus, having a diameter between 230-270 mm; installing a first hollow cylinder having an internal diameter larger, by 30-50 mm, than the feed rod's diameter; installing a second hollow cylinder having an internal diameter larger, by not 20-60 mm, than a crystal target diameter that is 290-310 mm; and pulling the single crystal of silicon. A pulling speed is 1.3-1.5 mm/min. A vertical distance of the bottom edge of the first hollow cylinder from the outer melting edge is smaller than 2 mm. The top edge of the second cylinder protrudes 1-10 mm over the crystallizing edge. A length of the single crystal is removed to form an ingot piece having a length 15-50 cm.

A crystal laminate structure includes an epitaxial growth substrate including a -Ga.sub.2O.sub.3-based single crystal and a (010) plane or a plane inclined at an angle not more than 37.5 with respect to the (010) plane as a main surface thereof and a high electrical resistance, and an epitaxial crystal formed on the main surface of the epitaxial growth substrate. The epitaxial crystal includes a Ga-containing oxide.

A casting method and cast article are provided. The casting method includes providing a casting furnace, the casting furnace including a withdrawal region in a lower end, positioning a mold within the casting furnace, positioning a molten material in the mold, partially withdrawing the mold a withdrawal distance through the withdrawal region in the casting furnace, the withdrawal distance providing a partially withdrawn portion, then reinserting at least a portion of the partially withdrawn portion into the casting furnace through the withdrawal region, and then completely withdrawing the mold from the casting furnace. The reinserting at least partially re-melts a solidified portion within the partially withdrawn portion to reduce or eliminate freckle grains. The cast article includes a microstructure and occurrence of freckle grains corresponding to being formed by a process comprising partially withdrawing, reinserting, and completely withdrawing of a mold from a casting furnace to form the cast article.

Plate-like samples each having as a principal plane thereof a cross section perpendicular to the long axis direction of a polycrystalline silicon rod grown by the deposition using a chemical vapor deposition method are sampled; an X-ray diffraction measurement is performed omnidirectionally in the plane of each of the plate-like samples thus sampled; and when none of the plate-like samples has any X-ray diffraction peak with a diffraction intensity deviating from the average value 2standard deviation (2) found for any one of the Miller indices <111>, <220>, <311> and <400>, the polycrystalline silicon rod is selected as the raw material for use in the production of single-crystalline silicon. The use of such a polycrystalline silicon raw material suppresses the local occurrence of the portions remaining unmelted, and can contribute to the stable production of single-crystalline silicon.

Plate-like samples each having as a principal plane thereof a cross section perpendicular to the long axis direction of a polycrystalline silicon rod grown by the deposition using a chemical vapor deposition method are sampled; an X-ray diffraction measurement is performed omnidirectionally in the plane of each of the plate-like samples thus sampled; and when none of the plate-like samples has any X-ray diffraction peak with a diffraction intensity deviating from the average value 2standard deviation (2) found for any one of the Miller indices <111>, <220>, <311> and <400>, the polycrystalline silicon rod is selected as the raw material for use in the production of single-crystalline silicon. The use of such a polycrystalline silicon raw material suppresses the local occurrence of the portions remaining unmelted, and can contribute to the stable production of single-crystalline silicon.

Suitability of silicon wafers for use in device processing without generation of fatal defects is assessed by using SIRD to measure stress in a wafer cut from a piece of a crystal ingot after first and second thermal treatments of the water, the second thermal treatment consisting of a heating phase, a holding phase, and a cooling phase. The result is used to consider whether silicon wafers cut from the piece can adequately survive device processing without generating excess defects.

The cathode member for electron beam generation of the present disclosure includes: 95% by area or more of a single phase or two phases of a compound composed of iridium and cerium. A total content of one or more subcomponents of metallic iridium and an oxide of one or more elements of iridium and cerium is 5% by area or less of the cathode member.

A silicon single crystal substrate for vapor phase growth, having the silicon single crystal substrate being made of an FZ crystal having a resistivity of 1000 cm or more, wherein the surface of the silicon single crystal substrate is provided with a high nitrogen concentration layer having a nitrogen concentration higher than that of other regions and a nitrogen concentration of 510.sup.15 atoms/cm.sup.3 or more and a thickness of 10 to 100 m.