A method for producing a Group III nitride crystal includes: preparing a protective layer on a region except for an epitaxial growth surface of an RAMO.sub.4 substrate containing a single crystal represented by the general formula RAMO.sub.4 (wherein R represents one or a plurality of a trivaient element selected from a group of elements including: Sc, In, Y, and a lanthanoid element, A represents one or a plurality of a trivalent element selected from a group of elements including: Fe(III), Ga, and Al, and M represents one or a plurality of a divalent element selected from a group of elements including: Mg, Mn, Fe(II), Co, Cu, Zn, and Cd); and forming a Group III nitride crystal on the epitaxial growth surface of the RAMO.sub.4 substrate by a flux method.

It is provided a method of growing a group 13 nitride crystal layer, on an underlying substrate including a seed crystal layer composed of a group 13 nitride. The underlying substrate is immersed in a melt containing a flux to grow a group 13 nitride crystal layer two-dimensionally on a nitrogen polar surface of the seed crystal layer by flux method.

A semiconductor device is provided. The semiconductor device includes a template layer disposed over a substrate and having a trench therein, a buffer structure disposed over a bottom surface of the trench and comprising a metal oxide, a single crystal semiconductor structure disposed within the trench and over the buffer structure and a gate structure disposed over a channel region of the single crystal semiconductor structure.

A semiconductor device is provided. The semiconductor device includes a template layer disposed over a substrate and having a trench therein, a buffer structure disposed over a bottom surface of the trench and comprising a metal oxide, a single crystal semiconductor structure disposed within the trench and over the buffer structure and a gate structure disposed over a channel region of the single crystal semiconductor structure.

A method for producing a Group III nitride crystal including preparing an RAMgO.sub.4 substrate containing a single crystal represented by the general formula RAMgO.sub.4 (wherein R represents one or a plurality of trivalent elements selected from the group consisting of Sc, In, Y, and a lanthanoid element, and A represents one or a plurality of trivalent elements selected from the group consisting of Fe(III), Ga, and Al); and growing a Group III nitride crystal containing Mg on the RAMgO.sub.4 substrate.

A method for producing a Group III nitride crystal including preparing an RAMgO.sub.4 substrate containing a single crystal represented by the general formula RAMgO.sub.4 (wherein R represents one or a plurality of trivalent elements selected from the group consisting of Sc, In, Y, and a lanthanoid element, and A represents one or a plurality of trivalent elements selected from the group consisting of Fe(III), Ga, and Al); and growing a Group III nitride crystal containing Mg on the RAMgO.sub.4 substrate.

A method of manufacturing a group-III nitride crystal includes: a seed crystal preparation step of preparing a plurality of dot-shaped group-III nitrides on a substrate as a plurality of seed crystals for growth of a group-III nitride crystal; and a crystal growth step of bringing surfaces of the seed crystals into contact with a melt containing an alkali metal and at least one group-III element selected from gallium, aluminum, and indium in an atmosphere containing nitrogen and thereby reacting the group-III element with the nitrogen in the melt to grow the group-III nitride crystal.

A method of manufacturing a group-III nitride crystal includes: a seed crystal preparation step of preparing a plurality of dot-shaped group-III nitrides on a substrate as a plurality of seed crystals for growth of a group-III nitride crystal; and a crystal growth step of bringing surfaces of the seed crystals into contact with a melt containing an alkali metal and at least one group-III element selected from gallium, aluminum, and indium in an atmosphere containing nitrogen and thereby reacting the group-III element with the nitrogen in the melt to grow the group-III nitride crystal.

A semiconductor device is provided. The semiconductor device includes a template layer disposed over a substrate and having a trench therein, a buffer structure disposed over a bottom surface of the trench and comprising a metal oxide, a single crystal semiconductor structure disposed within the trench and over the buffer structure and a gate structure disposed over a channel region of the single crystal semiconductor structure.

A semiconductor device is provided. The semiconductor device includes a template layer disposed over a substrate and having a trench therein, a buffer structure disposed over a bottom surface of the trench and comprising a metal oxide, a single crystal semiconductor structure disposed within the trench and over the buffer structure and a gate structure disposed over a channel region of the single crystal semiconductor structure.