The present invention provides a method for producing a Group III nitride crystal, capable of producing a Group III nitride crystal in a large size with few defects and high quality. The method is a method for producing a Group III nitride crystal (13), including: a seed crystal selection step of selecting plural parts of a Group III nitride crystal layer (11) as seed crystals for generation and growth of Group III nitride crystals (13); a contact step of causing the surfaces of the seed crystals to be in contact with an alkali metal melt; a crystal growth step of causing a Group III element and nitrogen to react with each other under a nitrogen-containing atmosphere in the alkali metal melt to generate and grow the Group III nitride crystals (13), wherein the seed crystals are hexagonal crystals, in the seed crystal selection step, the seed crystals are arranged so that m-planes of the respective crystals grown from the seed crystals that are adjacent to each other do not substantially coincide with each other, and in the crystal growth step, the plural Group III nitride crystals (13) grown from the plural seed crystals by the growth of the Group III nitride crystals (13) are bound.

Bulk crystal of group III nitride having thickness greater than 1 mm with improved crystal quality, reduced lattice bowing and/or reduced crack density and methods of making. Bulk crystal has a seed crystal, a first crystalline portion grown on the first side of the seed crystal and a second crystalline portion grown on the second side of the seed crystal. Either or both crystalline portions have an electron concentration and/or an oxygen concentration similar to the seed crystal. The bulk crystal can have an additional seed crystal, with common faces (e.g. same polarity, same crystal plane) of seed crystals joined so that a first crystalline part grows on the first face of the first seed crystal and a second crystalline part grows on the first face of the second seed crystal. Each crystalline part's electron concentration and/or oxygen concentration may be similar to its corresponding seed crystal.

A growth method of aluminum gallium nitride is disclosed. The method includes the steps of: providing a substrate; forming a first aluminum gallium nitride layer on the substrate at a first temperature; and forming a second aluminum gallium nitride layer, on the first aluminum gallium nitride layer, at a second temperature. The first temperature is higher than the second temperature.

According to one embodiment, a nitride crystal includes first, second, and third nitride crystal regions. The third nitride crystal region includes Al, and is provided between the first and second nitride crystal regions. A third oxygen concentration in the third nitride crystal region is greater than a first oxygen concentration in the first nitride crystal region and greater than a second oxygen concentration in the second nitride crystal region. A third carbon concentration in the third nitride crystal region is greater than a first carbon concentration in the first nitride crystal region and greater than a second carbon concentration in the second nitride crystal region. A <0001> direction of the first nitride crystal region is one of a first orientation from the second nitride crystal region toward the first nitride crystal region or a second orientation from the first nitride crystal region toward the second nitride crystal region.

A nonpolar III-nitride film grown on a miscut angle of a substrate, in order to suppress the surface undulations, is provided. The surface morphology of the film is improved with a miscut angle towards an a-axis direction comprising a 0.15° or greater miscut angle towards the a-axis direction and a less than 30° miscut angle towards the a-axis direction.

A method for growing a nitride film in accordance with an exemplary embodiment includes charging a substrate into a growth space, and growing a nitride film on the substrate, wherein the growing of a nitride film may include reacting a first reaction gas with a source raw material to supply a generated gas to the growth space, supplying a second reaction gas to the growth space, and supplying an oxygen-containing gas and a hydrogen-containing gas to the growth space. Accordingly, according to exemplary embodiments, even when a nitride film is formed thin, it is possible to planarize the upper surface of the nitride film. Accordingly, it is possible to reduce process time required to grow or form the nitride film until the upper surface thereof is planarized, and thus, there is an effect of improving the production rate.

A method for forming a lithium niobate- or lithium tantalum-based (LN/LT) layer includes providing a silicon-based substrate, forming nucleation layer on the substrate, and forming the LN/LT layer by epitaxy on the nucleation layer. The nucleation layer is chosen based upon a III-N material. The nucleation layer may be used in a surface acoustic wave device.

A layered body includes: a plate-like supporting body having a supporting main surface; and a plurality of projection portions disposed on the supporting main surface, each of the plurality of projection portions being composed of a group III nitride and having a dislocation density of not more than 1×10.sup.8 cm.sup.−3. The projection portion preferably has a polygonal planar shape. The projection portion preferably has a plate-like shape. Preferably, each of the plurality of projection portions has a main surface opposite to the supporting body and corresponding to a {0001} plane of the group III nitride of the projection portions, and the adjacent projection portions of the plurality of projection portions have end surfaces facing each other and corresponding to a {11-20} plane of the group III nitride of the projection portions.

An apparatus for manufacturing a group III nitride single crystal including: a reaction vessel including a reaction area, wherein in the reaction area, a group III source gas and a nitrogen source gas are reacted such that a group III nitride crystal is grown on a substrate; a susceptor arranged in the reaction area and supporting the substrate; a group III source gas supply nozzle supplying the group III source gas to the reaction area; and a nitrogen source gas supply nozzle supplying the nitrogen source gas to the reaction area, wherein the nitrogen source gas supply nozzle is configured to supply the nitrogen source gas and at least one halogen-based gas selected from the group consisting of a hydrogen halide gas and a halogen gas to the reaction area.

In various embodiments, controlled heating and/or cooling conditions are utilized during the fabrication of aluminum nitride single crystals and aluminum nitride bulk polycrystalline ceramics. Thermal treatments may also be utilized to control properties of aluminum nitride crystals after fabrication.