An oriented alumina substrate for epitaxial growth according to an embodiment of the present invention includes crystalline grains constituting a surface thereof, the crystalline grains having a tilt angle of 0.1 or more and less than 1.0 and an average sintered grain size of 10 m or more.

An oriented alumina substrate for epitaxial growth according to an embodiment of the present invention includes crystalline grains constituting a surface thereof, the crystalline grains having a tilt angle of 0.1 or more and less than 1.0 and an average sintered grain size of 10 m or more.

The present invention relates to the field of nonlinear optical crystal materials and provided herein a Li.sub.4Sr(BO.sub.3).sub.2 compound, a Li.sub.4Sr(BO.sub.3).sub.2 nonlinear optical crystal as well as preparation method and use thereof. The Li.sub.4Sr(BO.sub.3).sub.2 nonlinear optical crystal has a second harmonic conversion efficiency at 1064 nm of about two times that of a KH.sub.2PO.sub.4 (KDP) crystal, and an UV absorption cut-off edge less than 190 nm. Furthermore, the crystal did not disintegrate. By flux method with Li.sub.2O, Li.sub.2OB.sub.2O and Li.sub.2OB.sub.2O.sub.3LiF used as flux agent, large-size and transparent Li.sub.4Sr(BO.sub.3).sub.2 nonlinear optical crystal can grow. The Li.sub.4Sr(BO.sub.3).sub.2 crystal had stable physicochemical properties, moderate hardness, and was easy to cut, processing, preserve and use. Therefore it can be used for preparing nonlinear optical devices and thus for developing nonlinear optical applications in the ultraviolet and deep-ultraviolet band.

The present invention relates to the field of nonlinear optical crystal materials and provided herein a Li.sub.4Sr(BO.sub.3).sub.2 compound, a Li.sub.4Sr(BO.sub.3).sub.2 nonlinear optical crystal as well as preparation method and use thereof. The Li.sub.4Sr(BO.sub.3).sub.2 nonlinear optical crystal has a second harmonic conversion efficiency at 1064 nm of about two times that of a KH.sub.2PO.sub.4 (KDP) crystal, and an UV absorption cut-off edge less than 190 nm. Furthermore, the crystal did not disintegrate. By flux method with Li.sub.2O, Li.sub.2OB.sub.2O and Li.sub.2OB.sub.2O.sub.3LiF used as flux agent, large-size and transparent Li.sub.4Sr(BO.sub.3).sub.2 nonlinear optical crystal can grow. The Li.sub.4Sr(BO.sub.3).sub.2 crystal had stable physicochemical properties, moderate hardness, and was easy to cut, processing, preserve and use. Therefore it can be used for preparing nonlinear optical devices and thus for developing nonlinear optical applications in the ultraviolet and deep-ultraviolet band.

A crystal layer of a nitride of a group 13 element includes a pair of main surfaces. The crystal layer includes high carrier concentration regions having a carrier concentration of 110.sup.18/cm.sup.3 or more and low carrier concentration regions having a carrier concentration of 910.sup.17/cm.sup.3 or less, viewed in a cross section perpendicular to the main surfaces of the crystal layer. Each of the low carrier concentration regions is extended in an elongated shape. The low carrier concentration regions include association parts. The low carrier concentration regions are extended continuously between the pair of the main surfaces.

A crystal layer of a nitride of a group 13 element includes a pair of main surfaces. The crystal layer includes high carrier concentration regions having a carrier concentration of 110.sup.18/cm.sup.3 or more and low carrier concentration regions having a carrier concentration of 910.sup.17/cm.sup.3 or less, viewed in a cross section perpendicular to the main surfaces of the crystal layer. Each of the low carrier concentration regions is extended in an elongated shape. The low carrier concentration regions include association parts. The low carrier concentration regions are extended continuously between the pair of the main surfaces.

A method for producing a group 13 nitride single crystal includes dissolving and crystal growing. The dissolving includes dissolving nitrogen in a mixed melt in a reaction vessel that contains the mixed melt, a seed crystal, and a surrounding member. The mixed melt contains an alkali metal and a group 13 metal. The seed crystal is a seed crystal that is placed in the mixed melt and includes a group 13 nitride crystal in which a principal face is a c-plane. The surrounding member is arranged so as to surround the entire area of a side face of the seed crystal. The crystal growing includes growing a group 13 nitride crystal on the seed crystal.

Disclosed is a nonlinear optical material (NLO) for use in deep-UV applications, and methods of fabrication thereof. The NLO is fabricated from a plurality of components according to the formula A.sub.qB.sub.yC.sub.z and a crystallographic non-centrosymmetric (NCS) structure. The NLO material may be fabricated as a polycrystalline or a single crystal material. In an embodiment, the material may be according to a formula Ba.sub.3ZnB.sub.5PO.sub.14.

A composite substrate includes a sapphire substrate and a layer of a nitride of a group 13 element provided on the sapphire substrate. The layer of the nitride of the group 13 element is composed of gallium nitride, aluminum nitride or gallium aluminum nitride. The composite substrate satisfies the following formulas (1), (2) and (3). A laser light is irradiated to the composite substrate from the side of the sapphire substrate to decompose crystal lattice structure at an interface between the sapphire substrate and the layer of the nitride of the group 13 element. 5.0(an average thickness (m) of the layer of the nitride of the group 13 element/a diameter (mm) of the sapphire substrate)10.0 . . . (1); 0.1 a warpage (mm) of said composite substrate(50/a diameter (mm) of said composite substrate).sup.20.6 . . . (2); 1.10a maximum value (m) of a thickness of said layer of said nitride of said group 13 element/a minimum value (m) of said thickness of said layer of said nitride of said group 13 element . . . (3)

A composite substrate includes a sapphire substrate and a layer of a nitride of a group 13 element provided on the sapphire substrate. The layer of the nitride of the group 13 element is composed of gallium nitride, aluminum nitride or gallium aluminum nitride. The composite substrate satisfies the following formulas (1), (2) and (3). A laser light is irradiated to the composite substrate from the side of the sapphire substrate to decompose crystal lattice structure at an interface between the sapphire substrate and the layer of the nitride of the group 13 element. 5.0(an average thickness (m) of the layer of the nitride of the group 13 element/a diameter (mm) of the sapphire substrate)10.0 . . . (1); 0.1 a warpage (mm) of said composite substrate(50/a diameter (mm) of said composite substrate).sup.20.6 . . . (2); 1.10a maximum value (m) of a thickness of said layer of said nitride of said group 13 element/a minimum value (m) of said thickness of said layer of said nitride of said group 13 element . . . (3)