Method of manufacturing Group III nitride crystal substrate, etchant used in the method, Group III nitride crystal substrate, and semiconductor device including the same

A method of manufacturing a Group III nitride crystal substrate, comprising:

• (i) preparing a semiconductor seed layer of a Group III element compound;
• (ii) growing, on the semiconductor seed layer, a first semiconductor layer through liquid phase growth, the first semiconductor layer having a higher defect density than that of the semiconductor seed layer;
• (iii) growing, on the first semiconductor layer, a second semiconductor layer through liquid phase growth, the second semiconductor layer having a lower defect density than that of the first semiconductor layer;
• and
• (iv) removing at least the semiconductor seed layer and the first semiconductor layer to obtain a free-standing Group III nitride crystal substrate formed of the second semiconductor layer.

A method of manufacturing a Group III nitride crystal substrate, comprising:

• (I) preparing a semiconductor seed layer of a Group III element compound;
• (II) growing, on the semiconductor seed layer, a first semiconductor layer through liquid phase growth, the first semiconductor layer having a higher defect density than that of the semiconductor seed layer;
• (III) growing, on the first semiconductor layer, a second semiconductor layer through liquid phase growth, the second semiconductor layer having a lower defect density than that of the first semiconductor layer;
• and (IV) processing a surface of the second semiconductor layer.