An object of the present invention is to provide a method for producing a group III nitride crystal in which generation of breaking or cracks is less likely to occur. To achieve the object, the method for producing a group III nitride crystal includes: seed crystal preparation including disposing a plurality of crystals of a group III nitride as a plurality of seed crystals on a substrate; and crystal growth including growing group III nitride crystals by contacting a surface of each of the seed crystals with a melt containing at least one group III element selected from gallium, aluminum, and indium and an alkali metal in an atmosphere containing nitrogen. In the seed crystal preparation, the plurality of seed crystals are disposed within a hexagonal region provided on the substrate.

A method for forming a power semiconductor device is provided. The method includes: providing a semiconductor wafer grown by a Czochralski process and having a first side; forming an n-type substrate doping layer in the semiconductor wafer at the first side, the substrate doping layer having a doping concentration of at least 10.sup.17/cm.sup.3; and forming an epitaxy layer on the first side of the semiconductor wafer after forming the n-type substrate doping layer.

A method for preparing a single crystal silicon ingot and a wafer sliced therefrom are provided. The ingots and wafers comprise nitrogen at a concentration of at least about 11014 atoms/cm3 and/or germanium at a concentration of at least about 11019 atoms/cm3, interstitial oxygen at a concentration of less than about 6 ppma, and a resistivity of at least about 1000 ohm cm.

Methods for forming single crystal silicon ingots with improved resistivity control are disclosed. The methods involve growth of a sample rod. The sample rod may have a diameter less than the diameter of the product ingot. The sample rod is cropped to form a center slab. The resistivity of the center slab may be measured directly such as by a four-point probe. The sample rod may be annealed in a thermal donor kill cycle prior to measuring the resistivity.

The invention relates to a method for producing a strand from a monotectic alloy which is made of multiple constituents and in which drops of a primary phase are distributed in a uniform manner in a crystalline matrix in the solidified state. The uniform distribution can be achieved during the production process using the following method steps: a) melting the alloy constituents which consist of at least one matrix component and components that form the primary phase and heating the constituents to a temperature at which a single homogeneous phase exists; b) transporting the melt (2) in the form of strands in a transport direction which is inclined towards the horizontal at a transport speed; c) cooling the melt (2) while transporting the strand lower face perpendicularly to the transport direction in order to form a crystallization front when transporting in a cooling zone; d) setting the cooling intensity, the inclination of the transport direction, and the transport speed such that a horizontal crystallization front is formed and the Marangoni force produced by cooling and forming the primary phase in the form of drops is oriented anti-parallel to the gravitational force such that the drops of the primary phase in the matrix component move in the direction of the gravitational force; and e) drawing the alloy which has been solidified into the strand (9) out of the cooling zone.

A seed crystal holder for pulling up a single crystal is made of a carbon fiber-reinforced carbon composite material, and has a substantially cylindrical shape with a hollow space having a shape matching an outer shape of a substantially rod-shaped seed crystal. A direction of carbon fibers at a part in contact with at least an outer peripheral surface of the seed crystal has isotropy as viewed from a central axis of the hollow space.

A seed crystal holder for pulling up a single crystal is made of a carbon fiber-reinforced carbon composite material, and has a substantially cylindrical shape with a hollow space having a shape matching an outer shape of a substantially rod-shaped seed crystal. A direction of carbon fibers at a part in contact with at least an outer peripheral surface of the seed crystal has isotropy as viewed from a central axis of the hollow space.

Methods for preparing single crystal silicon substrates for epitaxial growth are disclosed. The methods may involve control of the (i) a growth velocity, v, and/or (ii) an axial temperature gradient, G, during the growth of an ingot segment such that v/G is less than a critical v/G and/or is less than a value of v/G that depends on the boron concentration of the ingot. Methods for preparing epitaxial wafers are also disclosed.

Methods for preparing single crystal silicon substrates for epitaxial growth are disclosed. The methods may involve control of the (i) a growth velocity, v, and/or (ii) an axial temperature gradient, G, during the growth of an ingot segment such that v/G is less than a critical v/G and/or is less than a value of v/G that depends on the boron concentration of the ingot. Methods for preparing epitaxial wafers are also disclosed.

Methods for preparing an ingot in an ingot puller apparatus are disclosed. Thermal simulations are performed with the length of the ingot puller apparatus side heater being varied in the thermal simulations. A side heater is selected based on the thermal simulations. An ingot puller apparatus having the selected side heater length is provided. A seed crystal is lowered into a melt within a crucible of the ingot puller apparatus and an ingot is withdrawn from the melt.