Gallium nitride single crystal substrate
There is provided a gallium nitride single crystal substrate, which is a gallium nitride single crystal substrate that has a diameter of 50 mm or more and whose low index crystal plane closest to a main surface is a (0001) plane, wherein a density of etch pits when applying etching to the main surface with an alkaline etching solution is less than 1×10 6 cm −2 , and among peaks appearing in a histogram of diameters of the etch pits, when a diameter of a first peak appearing on a smallest diameter-side is a, a total number of the etch pits with a diameter exceeding 4a is 1/1000 or less of a number of etch pits forming the first peak.
1 . A gallium nitride single crystal substrate, which is a gallium nitride single crystal substrate that has a diameter of 50 mm or more and whose low index crystal plane closest to a main surface is a (0001) plane,
wherein a density of etch pits when applying etching to the main surface with an alkaline etching solution is less than 1×10 6 cm −2 , and
among peaks appearing in a histogram of diameters of the etch pits, when a diameter of a first peak appearing on a smallest diameter-side is a, a total number of the etch pits with a diameter of 2a or more is 1/10 or less of a number of etch pits forming the first peak.
2 . A gallium nitride single crystal substrate, which is a gallium nitride single crystal substrate that has a diameter of 50 mm or more and whose low index crystal plane closest to a main surface is a (0001) plane,
wherein a density of etch pits when applying etching to the main surface with an alkaline etching solution is less than 1×10 6 cm −2 , and
among peaks appearing in a histogram of diameters of the etch pits, when a peak appearing on a smallest diameter-side is a first peak, the number of etch pits forming the first peak is 50% or more of a total.
3 . A gallium nitride single crystal substrate, which is a gallium nitride single crystal substrate that has a diameter of 50 mm or more and whose low index crystal plane closest to a main surface is a (0001) plane,
wherein a density of etch pits when applying etching to the main surface with an alkaline etching solution is less than 1×10 6 cm −2 , and
among peaks appearing in a histogram of diameters of the etch pits, when a frequency of a peak appearing on a smallest diameter-side is A, a number of peaks with a frequency of A/10 or more appearing in the histogram is two, including the first peak.
4 . A gallium nitride single crystal substrate, which is a gallium nitride single crystal substrate that has a diameter of 50 mm or more and whose low index crystal plane closest to a main surface is a (0001) plane,
wherein a density of etch pits when applying etching to the main surface with an alkaline etching solution is less than 1×10 6 cm −2 , and
among peaks appearing in a histogram of diameters of the etch pits, when a diameter of a first peak appearing on a smallest diameter-side is a, having a second peak in a diameter range of more than a and less than 2a, wherein a number of etch pits forming the second peak is smaller than a number of etch pits forming the first peak.
5 . The gallium nitride single crystal substrate according to claim 1 , wherein a density and a histogram of the etch pits are measured from a region with an area of 1 mm 2 or more.
6 . The gallium nitride single crystal substrate according to claim 2 , wherein a density and a histogram of the etch pits are measured from a region with an area of 1 mm 2 or more.
7 . The gallium nitride single crystal substrate according to claim 3 , wherein a density and a histogram of the etch pits are measured from a region with an area of 1 mm 2 or more.
8 . The gallium nitride single crystal substrate according to claim 4 , wherein a density and a histogram of the etch pits are measured from a region with an area of 1 mm 2 or more.