III-V group nitride system semiconductor self-standing substrate, method of making the same and III-V group nitride system semiconductor wafer

A III-V group nitride system semiconductor self-standing substrate, comprising:

• III-V group nitride system semiconductor crystal, wherein the substrate comprises:
• a first III-V group nitride system semiconductor crystal layer that comprises a region with dislocation lines gathered densely, the dislocation lines being gathered substantially perpendicular to a surface of the substrate, and a region with dislocation lines gathered thinly;
• and
• a second III-V group nitride system semiconductor crystal layer that is formed up to 10 μm from the surface of the substrate on the first III-V group nitride system semiconductor crystal layer and that has a dislocation density distribution that is substantially uniform.

A method of making a III-V group nitride system semiconductor self-standing substrate, comprising the steps of:

• growing a III-V group nitride system semiconductor crystal while generating a plurality of concaves on a crystal growth interface;
• flattening the crystal growth interface by growing the III-V group nitride system semiconductor crystal to fill the plurality of concaves, whereby dislocation lines generated in the crystal are gathered while reducing a dislocation density of the entire III-V group nitride system semiconductor crystal, and a first III-V group nitride system semiconductor crystal layer is formed that comprises a region with dislocation lines gathered densely, the dislocation lines being gathered substantially perpendicular to a surface of the substrate, and a region with dislocation lines gathered thinly;
• and
• subsequently growing the crystal while keeping the crystal growth interface flattened, whereby a transitional layer is formed that the dislocation lines once gathered are uniformly dispersed again in the crystal, and a second III-V group nitride system semiconductor crystal layer is formed with a thickness of 10 μm or more on the transitional layer, the second III-V group nitride system semiconductor crystal layer having a low dislocation density and a substantially uniform dislocation density distribution.

A method of making a III-V group nitride system semiconductor self-standing substrate, comprising the steps of:

• growing a III-V group nitride system semiconductor crystal while generating a plurality of concaves on a crystal growth interface;
• flattening the crystal growth interface by growing the III-V group nitride system semiconductor crystal to fill the plurality of concaves, whereby dislocation lines generated in the crystal are gathered while reducing a dislocation density of the entire III-V group nitride system semiconductor crystal, and a first III-V group nitride system semiconductor crystal layer is formed that comprises a region with dislocation lines gathered densely, the dislocation lines being gathered substantially perpendicular to a surface of the substrate, and a region with dislocation lines gathered thinly;
• subsequently growing the crystal while keeping the crystal growth interface flattened, whereby a transitional layer is formed that the dislocation lines once gathered are uniformly dispersed again in the crystal, and a second III-V group nitride system semiconductor crystal layer is formed with a thickness of 10 μm or more on the transitional layer, the second III-V group nitride system semiconductor crystal layer having a low dislocation density and a substantially uniform dislocation density distribution;
• and
• polishing a surface of the substrate such that the second III-V group nitride system semiconductor crystal layer has a thickness of 10 μm or more after the polishing.

A method of making a III-V group nitride system semiconductor self-standing substrate, comprising the steps of:

• growing a III-V group nitride system semiconductor crystal on a hetero-substrate while generating a plurality of concaves on a crystal growth interface;
• flattening the crystal growth interface by growing the III-V group nitride system semiconductor crystal to fill the plurality of concaves, whereby dislocation lines generated in the crystal are gathered while reducing a dislocation density of the entire III-V group nitride system semiconductor crystal, and a first III-V group nitride system semiconductor crystal layer is formed that comprises a region with dislocation lines gathered densely, the dislocation lines being gathered substantially perpendicular to a surface of the substrate, and a region with dislocation lines gathered thinly;
• subsequently growing the crystal while keeping the crystal growth interface flattened, whereby a transitional layer is formed that the dislocation lines once gathered are uniformly dispersed again in the crystal, and a second III-V group nitride system semiconductor crystal layer is formed with a thickness of 10 μm or more on the transitional layer, the second III-V group nitride system semiconductor crystal layer having a low dislocation density and a substantially uniform dislocation density distribution;
• and
• separating the III-V group nitride system semiconductor crystal grown on the hetero-substrate from the hetero-substrate.

A method of making a III-V group nitride system semiconductor self-standing substrate, comprising the steps of:

• growing a III-V group nitride system semiconductor crystal on a hetero-substrate while generating a plurality of concaves on a crystal growth interface;
• flattening the crystal growth interface by growing the III-V group nitride system semiconductor crystal to fill the plurality of concaves, whereby dislocation lines generated in the crystal are gathered while reducing a dislocation density of the entire III-V group nitride system semiconductor crystal, and a first III-V group nitride system semiconductor crystal layer is formed that comprises a region with dislocation lines gathered densely, the dislocation lines being gathered substantially perpendicular to a surface of the substrate, and a region with dislocation lines gathered thinly;
• subsequently growing the crystal while keeping the crystal growth interface flattened, whereby a transitional layer is formed that the dislocation lines once gathered are uniformly dispersed again in the crystal, and a second III-V group nitride system semiconductor crystal layer is formed with a thickness of 10 μm or more on the transitional layer, the second III-V group nitride system semiconductor crystal layer having a low dislocation density and a substantially uniform dislocation density distribution;
• separating the III-V group nitride system semiconductor crystal grown on the hetero-substrate from the hetero-substrate;
• and
• subsequently polishing a surface of the substrate such that the second III-V group nitride system semiconductor crystal layer has a thickness of 10 μm or more after the polishing.

A method of making a III-V group nitride system semiconductor self-standing substrate, comprising the steps of:

• growing a III-V group nitride system semiconductor crystal while generating a plurality of concaves on a crystal growth interface;
• flattening the crystal growth interface by growing the III-V group nitride system semiconductor crystal to fill the plurality of concaves, whereby dislocation lines generated in the crystal are gathered while reducing a dislocation density of the entire III-V group nitride system semiconductor crystal, and a first III-V group nitride system semiconductor crystal layer is formed that comprises a region with dislocation lines gathered densely, the dislocation lines being gathered substantially perpendicular to a surface of the substrate, and a region with dislocation lines gathered thinly;
• subsequently growing the crystal while keeping the crystal growth interface flattened, whereby a transitional layer is formed that the dislocation lines once gathered are uniformly dispersed again in the crystal, and a second III-V group nitride system semiconductor crystal layer is formed with a thickness of 10 μm or more on the transitional layer, the second III-V group nitride system semiconductor crystal layer having a low dislocation density and a substantially uniform dislocation density distribution;
• and
• removing part of the first III-V group nitride system semiconductor crystal layer.

A method of making a III-V group nitride system semiconductor self-standing substrate, comprising the steps of:

• growing a III-V group nitride system semiconductor crystal on a hetero-substrate while generating a plurality of concaves on a crystal growth interface;
• flattening the crystal growth interface by growing the III-V group nitride system semiconductor crystal to fill the plurality of concaves, whereby dislocation lines generated in the crystal are gathered while reducing a dislocation density of the entire III-V group nitride system semiconductor crystal, and a first III-V group nitride system semiconductor crystal layer is formed that comprises a region with dislocation lines gathered densely, the dislocation lines being gathered substantially perpendicular to a surface of the substrate, and a region with dislocation lines gathered thinly;
• subsequently growing the crystal while keeping the crystal growth interface flattened, whereby a transitional layer is formed that the dislocation lines once gathered are uniformly dispersed again in the crystal, and a second III-V group nitride system semiconductor crystal layer is formed with a thickness of 10 μm or more on the transitional layer, the second III-V group nitride system semiconductor crystal layer having a low dislocation density and a substantially uniform dislocation density distribution;
• separating the III-V group nitride system semiconductor crystal grown on the hetero-substrate from the hetero-substrate;
• and
• subsequently removing part of the first III-V group nitride system semiconductor crystal layer.