A nonpolar III-nitride film grown on a miscut angle of a substrate. The miscut angle towards the <000-1> direction is 0.75° or greater miscut and less than 27° miscut towards the <000-1> direction. Surface undulations are suppressed and may comprise faceted pyramids. A device fabricated using the film is also disclosed. A nonpolar III-nitride film having a smooth surface morphology fabricated using a method comprising selecting a miscut angle of a substrate upon which the nonpolar III-nitride films are grown in order to suppress surface undulations of the nonpolar III-nitride films. A nonpolar III-nitride-based device grown on a film having a smooth surface morphology grown on a miscut angle of a substrate which the nonpolar III-nitride films are grown. The miscut angle may also be selected to achieve long wavelength light emission from the nonpolar film.

A nucleation layer comprised of group III and V elements is directly deposited onto the surface of a substrate made of a group IV element. Together with a first gaseous starting material containing a group III element, a second gaseous starting material containing a group V element is introduced at a process temperature of greater than 500° C. into a process chamber containing the substrate. It is essential that at least at the start of the deposition process of the nucleation layer, a third gaseous starting material containing a group IV element is fed into the process chamber, together with the first and second gaseous starting material. The third gaseous starting material develops an n-doping effect in the deposited III-V crystal, which causes a decrease in damping at a dopant concentration of less than 1×10.sup.18 cm.sup.−3.

A nitride semiconductor free-standing substrate includes a diameter of not less than 40 mm, a thickness of not less than 100 μm, a dislocation density of not more than 5×10.sup.6/cm.sup.2, an impurity concentration of not more than 4×10.sup.19/cm.sup.3, and a nanoindentation hardness of not less than 19.0 GPa at a maximum load in a range of not less than 1 mN and not more than 50 mN.

There is provided a method for manufacturing a group III nitride substrate, including: preparing a plurality of seed crystal substrates formed into shapes that can be arranged with side surfaces opposed to each other; bonding the plurality of seed crystal substrates on a base material by an adhesive agent in an appearance that the seed crystal substrates are arranged with the side surfaces opposed to each other; growing a group III nitride crystals above main surfaces of the plurality of seed crystal substrates, so that crystals grown on each main surface are integrally combined each other; and obtaining a group III nitride substrate formed of the group III nitride crystal.

To fabricate a practically useful non-polar AlN buffer layer on a sapphire crystal plate and manufacture a UV light-emitting device on a non-polar crystal substrate by adopting the crystal substrate as an example, an embodiment of the present invention provides a crystal substrate 1D comprising an r-plane sapphire crystal plate 10 and an AlN buffer layer 20D of non-polar orientation. The AlN buffer layer comprises a surface protection layer 22 and a smoothing layer 26. The surface protection layer suppresses roughness increase on a surface of the AlN buffer layer, and the smoothing layer makes the surface of the AlN buffer layer a smoothed surface. Also provided is a crystal substrate 11 comprising an AlN buffer layer 20T to which a dislocation blocking layer 24 for reducing crystallographic defects is added between the surface protection layer 22 and the smoothing layer 26. In another embodiment a deep UV light-emitting device is provided.

A vertical nitride semiconductor device includes an n-type aluminum nitride single-crystal substrate having an Si content of 3×10.sup.17 to 1×10.sup.20 cm.sup.−3 and a dislocation density of 10.sup.6 cm.sup.−2 or less. An ohmic electrode layer is formed on an N-polarity side of the n-type aluminum nitride single-crystal substrate.

A crystal growth method of the present disclosure includes: preparing a substrate having a surface layer; forming a mask pattern including a plurality of strip bodies on the surface layer to separate the surface layer into segments by the plurality of strip bodies and expose part of the surface layer; and forming, on a plurality of growth regions constituted by the exposed part of the surface layer, a crystal growth-derived layer by causing a semiconductor crystal which differs in lattice constant from the substrate to grow by a vapor-phase growth process. Each of the plurality of strip bodies has side faces inclined so that a width between the side faces gradually decreases with distance from the surface layer.

An interface including roughness components for improving the propagation of radiation through the interface is provided. The interface includes a first profiled surface of a first layer comprising a set of large roughness components providing a first variation of the first profiled surface having a first characteristic scale and a second profiled surface of a second layer comprising a set of small roughness components providing a second variation of the second profiled surface having a second characteristic scale. The first characteristic scale is approximately an order of magnitude larger than the second characteristic scale. The surfaces can be bonded together using a bonding material, and a filler material also can be present in the interface.

A high-quality nitride crystal can be produced efficiently by charging a nitride crystal starting material that contains tertiary particles having a maximum diameter of from 1 to 120 mm and formed through aggregation of secondary particles having a maximum diameter of from 100 to 1000 μm, in the starting material charging region of a reactor, followed by crystal growth in the presence of a solvent in a supercritical state and/or a subcritical state in the reactor, wherein the nitride crystal starting material is charged in the starting material charging region in a bulk density of from 0.7 to 4.5 g/cm.sup.3 for the intended crystal growth.

A group 13 nitride crystal having a hexagonal crystal structure and containing at least a nitrogen atom and at least a metal atom selected from a group consisting of B, Al, Ga, In, and Tl. The group 13 nitride crystal includes a first region disposed on an inner side in a cross section intersecting c-axis, a third region disposed on an outermost side in the cross section and having a crystal property different from that of the first region, and a second region disposed at least partially between the first region and the third region in the cross section, the second region being a transition region of a crystal growth and having a crystal property different from that of the first region and that of the third region.