Patent ID: 8002892

Claim:
A Group-III nitride crystal substrate manufacturing method comprising: a step of growing, by liquid-phase epitaxy utilizing gaseous N 2 as a source material, a first Group-III nitride crystal onto a freestanding Group-III nitride crystal base substrate, and in the growth of the first Group-III nitride crystal, forming in the growth surface first Group-III nitride crystal features on a floor thereof; a step of growing, by hydride vapor-phase epitaxy onto the first Group-III nitride crystal surface having the features and the floor, a second Group-III nitride crystal to a thickness of at least 1600 μm to thereby impart to the second Group-III nitride crystal a dislocation density of not greater than 3×10 6 /cm 2 , in such a way that the growth rate V H of the second Group-III nitride crystal on sloping surfaces of the features on the first Group-III nitride crystal is greater than the growth rate V v of the second Group-III nitride crystal on the flat surface of the floor of, and on flat surfaces of the features on, the first Group-III nitride crystal, and such that the second Group-III nitride crystal covers over the flat surface of the floor and the flat surfaces of the features; and a step of dividing the first Group-III nitride crystal and/or the second Group-III nitride crystal, by slicing or cleavage.