Provided are a Ga.sub.2O.sub.3-based single crystal substrate including a Ga.sub.2O.sub.3-based single crystal which has a high resistance while preventing a lowering of crystal quality and a production method therefor. According to one embodiment of the present invention, the production method includes growing the Ga.sub.2O.sub.3-based single crystal while adding a Fe to a Ga.sub.2O.sub.3-based raw material, the Ga.sub.2O.sub.3-based single crystal (5) including the Fe at a concentration higher than that of a donor impurity mixed in the Ga.sub.2O.sub.3-based raw material, and cutting out the Ga.sub.2O.sub.3-based single crystal substrate from the Ga.sub.2O.sub.3-based single crystal (5).

Provided are a Ga.sub.2O.sub.3-based single crystal substrate including a Ga.sub.2O.sub.3-based single crystal which has a high resistance while preventing a lowering of crystal quality and a production method therefor. According to one embodiment of the present invention, the production method includes growing the Ga.sub.2O.sub.3-based single crystal while adding a Fe to a Ga.sub.2O.sub.3-based raw material, the Ga.sub.2O.sub.3-based single crystal (5) including the Fe at a concentration higher than that of a donor impurity mixed in the Ga.sub.2O.sub.3-based raw material, and cutting out the Ga.sub.2O.sub.3-based single crystal substrate from the Ga.sub.2O.sub.3-based single crystal (5).

A method of method of forming or repairing a superalloy article having a columnar or equiaxed or directionally solidified or amorphous or single crystal microstructure includes emitting a plurality of laser beams from selected fibers of a diode laser fiber array corresponding to a pattern of a layer of the article onto a powder bed of the superalloy to form a melt pool; and controlling a temperature gradient and a solidification velocity of the melt pool to form the columnar or single crystal microstructure.

A method of method of forming or repairing a superalloy article having a columnar or equiaxed or directionally solidified or amorphous or single crystal microstructure includes emitting a plurality of laser beams from selected fibers of a diode laser fiber array corresponding to a pattern of a layer of the article onto a powder bed of the superalloy to form a melt pool; and controlling a temperature gradient and a solidification velocity of the melt pool to form the columnar or single crystal microstructure.

FZ single crystals are pulled by melting a polycrystal with electromagnetic melting apparatus and then recrystallizing. First, a lower end of the polycrystal is melted; second, a monocrystalline seed is attached to the lower end of the polycrystal and melted beginning from an upper end thereof; third, between a lower section of the seed and the polycrystal, a thin neck is formed whose diameter (d.sub.D) is smaller than that (d.sub.I) of the seed; and fourth, between the thin neck section and the polycrystal, a conical section is formed. Before the conical growth, a switchover position (h) of the polycrystal, the position at which the rate of polycrystal movement relative to the melting apparatus is to be reduced is determined, and the rate is reduced, in amount when the switchover position (h) is reached.

FZ single crystals are pulled by melting a polycrystal with electromagnetic melting apparatus and then recrystallizing. First, a lower end of the polycrystal is melted; second, a monocrystalline seed is attached to the lower end of the polycrystal and melted beginning from an upper end thereof; third, between a lower section of the seed and the polycrystal, a thin neck is formed whose diameter (d.sub.D) is smaller than that (d.sub.I) of the seed; and fourth, between the thin neck section and the polycrystal, a conical section is formed. Before the conical growth, a switchover position (h) of the polycrystal, the position at which the rate of polycrystal movement relative to the melting apparatus is to be reduced is determined, and the rate is reduced, in amount when the switchover position (h) is reached.

A laser heated pedestal growth system includes two lasers having output beams that are combined with a beam combiner to produce a single beam. A growth chamber that includes a final focusing mirror for receiving and focusing the single beam of the lasers onto a tip of a feed material to create a molten zone in a focal region. A feed transport mechanism is adapted for transporting a feed material through the growth chamber and into the molten zone. An opposing seed transport mechanism is adapted for withdrawing a seed material from the growth chamber. An imaging system is adapted for capturing an image of the molten zone within the growth chamber. A controller in communication with the feed transport mechanism, the seed transport mechanism, one of the two lasers, and the imagining system is adapted to control and stabilize a fiber growth process by controlling the feed transport mechanism, the seed transport mechanism, and the power of the combined laser beam.

Provided are a Ga.sub.2O.sub.3-based single crystal substrate including a Ga.sub.2O.sub.3-based single crystal which has a high resistance while preventing a lowering of crystal quality and a production method therefor. According to one embodiment of the present invention, the production method includes growing the Ga.sub.2O.sub.3-based single crystal while adding a Fe to a Ga.sub.2O.sub.3-based raw material, the Ga.sub.2O.sub.3-based single crystal (5) including the Fe at a concentration higher than that of a donor impurity mixed in the Ga.sub.2O.sub.3-based raw material, and cutting out the Ga.sub.2O.sub.3-based single crystal substrate from the Ga.sub.2O.sub.3-based single crystal (5).

Provided are a Ga.sub.2O.sub.3-based single crystal substrate including a Ga.sub.2O.sub.3-based single crystal which has a high resistance while preventing a lowering of crystal quality and a production method therefor. According to one embodiment of the present invention, the production method includes growing the Ga.sub.2O.sub.3-based single crystal while adding a Fe to a Ga.sub.2O.sub.3-based raw material, the Ga.sub.2O.sub.3-based single crystal (5) including the Fe at a concentration higher than that of a donor impurity mixed in the Ga.sub.2O.sub.3-based raw material, and cutting out the Ga.sub.2O.sub.3-based single crystal substrate from the Ga.sub.2O.sub.3-based single crystal (5).

Provided are a Ga.sub.2O.sub.3-based single crystal substrate including a Ga.sub.2O.sub.3-based single crystal which has a high resistance while preventing a lowering of crystal quality and a production method therefor. According to one embodiment of the present invention, the production method includes growing the Ga.sub.2O.sub.3-based single crystal while adding a Fe to a Ga.sub.2O.sub.3-based raw material, the Ga.sub.2O.sub.3-based single crystal (5) including the Fe at a concentration higher than that of a donor impurity mixed in the Ga.sub.2O.sub.3-based raw material, and cutting out the Ga.sub.2O.sub.3-based single crystal substrate from the Ga.sub.2O.sub.3-based single crystal (5).