Growth of single crystal epitaxial films of the perovskite crystal structure by liquid- or vapor-phase means can be accomplished by providing single-crystal perovskite substrate materials of improved lattice parameter match in the lattice parameter range of interest. Current substrates do not provide as good a lattice match, have inferior properties, or are of limited size and availability because cost of materials and difficulty of growth. This problem is solved by the single-crystal perovskite solid solutions described herein grown from mixtures with an indifferent melting point that occurs at a congruently melting composition at a temperature minimum in the melting curve in the pseudo-binary molar phase diagram. Accordingly, single-crystal perovskite solid solutions, structures, and devices including single-crystal perovskite solid solutions, and methods of making single-crystal perovskite solid solutions are described herein.

Growth of single crystal epitaxial films of the perovskite crystal structure by liquid- or vapor-phase means can be accomplished by providing single-crystal perovskite substrate materials of improved lattice parameter match in the lattice parameter range of interest. Current substrates do not provide as good a lattice match, have inferior properties, or are of limited size and availability because cost of materials and difficulty of growth. This problem is solved by the single-crystal perovskite solid solutions described herein grown from mixtures with an indifferent melting point that occurs at a congruently melting composition at a temperature minimum in the melting curve in the pseudo-binary molar phase diagram. Accordingly, single-crystal perovskite solid solutions, structures, and devices including single-crystal perovskite solid solutions, and methods of making single-crystal perovskite solid solutions are described herein.

A 4H-SiC single crystal having good morphology while preventing heterogeneous polymorphs from being mixed in regardless of the presence or absence of doping in growing a 4H-SiC single crystal by the TSSG method is obtained. When the off-angle on the grown crystal in a method for producing a SiC single crystal by a TSSG method is set to 60 to 68, heterogeneous polymorphs are less likely to be mixed in during the growth of 4H-SiC single crystal, and if, during that period, a meltback method is used to smooth the surface of the seed crystal and then grow the crystal, it is possible to obtain a grown crystal having good morphology.

A process for forming an epitaxial film comprising spinning a substrate having an ordered crystal structure; heating the substrate during spinning to a temperature between 70 C. and 150 C.; dripping epitaxial film precursor solution onto the spinning substrate, where the precursor solution comprises inorganic film precursor material in a solvent; and continuing the heating and spinning to remove the solvent and epitaxially grow the epitaxial film on the substrate.

A process for forming an epitaxial film comprising spinning a substrate having an ordered crystal structure; heating the substrate during spinning to a temperature between 70 C. and 150 C.; dripping epitaxial film precursor solution onto the spinning substrate, where the precursor solution comprises inorganic film precursor material in a solvent; and continuing the heating and spinning to remove the solvent and epitaxially grow the epitaxial film on the substrate.

A free-standing substrate of a polycrystalline nitride of a group 13 element contains a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The polycrystalline nitride of the group 13 element is composed of gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof. The free-standing substrate has a top surface and bottom surface. The free-standing substrate contains at least one of zinc and calcium. A root mean square roughness Rms at the top surface is 3.0 nm or less.

A free-standing substrate of a polycrystalline nitride of a group 13 element contains a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The polycrystalline nitride of the group 13 element is composed of gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof. The free-standing substrate has a top surface and bottom surface. The free-standing substrate contains at least one of zinc and calcium. A root mean square roughness Rms at the top surface is 3.0 nm or less.

The present invention reduces warpage of a Group III nitride semiconductor crystal in a method for producing a Group III nitride semiconductor crystal on a seed substrate through a flux method. A Group III nitride semiconductor is grown so that the total Al amount at the interface is not more than 310.sup.14/cm.sup.2, and the total Si amount at the interface is not more than 510.sup.14/cm.sup.2. Here, the total amount at the interface refers to a total number of atoms per unit area of an interface between the grown Group III nitride semiconductor and the seed substrate. Thus, warpage can be reduced by growing a Group III nitride semiconductor through a flux method.

The present invention reduces warpage of a Group III nitride semiconductor crystal in a method for producing a Group III nitride semiconductor crystal on a seed substrate through a flux method. A Group III nitride semiconductor is grown so that the total Al amount at the interface is not more than 310.sup.14/cm.sup.2, and the total Si amount at the interface is not more than 510.sup.14/cm.sup.2. Here, the total amount at the interface refers to a total number of atoms per unit area of an interface between the grown Group III nitride semiconductor and the seed substrate. Thus, warpage can be reduced by growing a Group III nitride semiconductor through a flux method.

A semiconductor wafer forms on a mold containing a dopant. The dopant dopes a melt region adjacent the mold. There, dopant concentration is higher than in the melt bulk. A wafer starts solidifying. Dopant diffuses poorly in solid semiconductor. After a wafer starts solidifying, dopant can not enter the melt. Afterwards, the concentration of dopant in the melt adjacent the wafer surface is less than what was present where the wafer began to form. New wafer regions grow from a melt region whose dopant concentration lessens over time. This establishes a dopant gradient in the wafer, with higher concentration adjacent the mold. The gradient can be tailored. A gradient gives rise to a field that can function as a drift or back surface field. Solar collectors can have open grid conductors and better optical reflectors on the back surface, made possible by the intrinsic back surface field.