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 1 or more and 3 or less and an average sintered grain size of 20 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.

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.

Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer formed of Al-doped GaN and suppresses diffusion of Zn from the free-standing substrate into the channel layer.

Provided is an epitaxial substrate for semiconductor elements which suppresses an occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN being doped with Zn; a buffer layer being adjacent to the free-standing substrate; a channel layer being adjacent to the buffer layer; and a barrier layer being provided on an opposite side of the buffer layer with the channel layer therebetween, wherein the buffer layer is a diffusion suppressing layer formed of Al-doped GaN and suppresses diffusion of Zn from the free-standing substrate into the channel layer.

Disclosed is a nonlinear optical (NLO) material 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.

An epitaxial substrate for semiconductor elements which suppresses the occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer adjacent to the free-standing substrate; a channel layer adjacent to the buffer layer; and a barrier layer provided on an opposite side of the buffer layer with the channel layer provided therebetween, wherein the buffer layer is a diffusion suppressing layer that suppresses the diffusion of Zn from the free-standing substrate into the channel layer.

An epitaxial substrate for semiconductor elements which suppresses the occurrence of current collapse. The epitaxial substrate for the semiconductor elements includes: a semi-insulating free-standing substrate formed of GaN doped with Zn; a buffer layer adjacent to the free-standing substrate; a channel layer adjacent to the buffer layer; and a barrier layer provided on an opposite side of the buffer layer with the channel layer provided therebetween, wherein the buffer layer is a diffusion suppressing layer that suppresses the diffusion of Zn from the free-standing substrate into the channel layer.

There is provided a semiconductor substrate including: a sapphire substrate; an intermediate layer formed of gallium nitride with random crystal directions and provided on the sapphire substrate; and at least one or more semiconductor layers each of which is formed of a gallium nitride single crystal and that are provided on the intermediate layer.

A production method for a group III nitride crystal, the production method includes: preparing a plurality of group III nitride pieces as a plurality of seed crystals on a substrate, and growing a group III nitride crystal by bringing a surface of each of the seed crystals into contact with a melt that comprises at least one group III element selected from gallium, aluminum, and indium, and an alkali metal in an atmosphere comprising nitrogen, and thereby reacting the group III element and the nitrogen in the melt, wherein the step of growing a group III nitride crystal includes: growing a plurality of first group III nitride crystals whose cross-sections each have a triangular shape or a trapezoidal shape, from the plurality of seed crystals; and growing second group III nitride crystals each in a gap among the plurality of first group III nitride crystals.