Abstract: An image comparison apparatus includes an image comparison portion. The image comparison portion generates a shadow target image which is an image of a portion of a shadow in a target image. The image comparison portion generates a shadow reference image corresponding to the shadow target image in a reference image. The image comparison portion matches a tone of the two shadow images. The image comparison portion generates a non-shadow target image in the target image and a non-shadow reference image in the reference image. The image comparison portion matches a tone of the two non-shadow images. The image comparison portion generates the target image from which the shadow has been removed by synthesizing the shadow target image and the non-shadow target image. The image comparison portion compares the reference image and the target image from which the shadow has been removed.

Abstract: An image comparison apparatus includes an image comparison portion configured to compare a reference image with a target image. The image comparison portion calculates a degree of blur of each of the reference image and the target image. The image comparison apparatus reduces a difference in the degree of blur between the reference image and the target image to within a specific range by adding blur to one of the reference image and the target image that has a smaller degree of blur. The image comparison apparatus compares the reference image and the target image whose difference in the degree of blur has been reduced to within the specific range.

Abstract: The image comparison portion calculates a plurality of pixel SSIM values of a first image and a second image and a representative SSIM value which is an overall SSIM value of both images. The image comparison portion identifies one or more count target SSIM values that belong to a specific range below a first threshold value among the plurality of pixel SSIM values when the representative SSIM value is equal to or greater than the first threshold value. The image comparison portion adds up a number of pixels for each level of the one or more count target SSIM values in both images with a weight according to each level of the one or more count target SSIM values to calculate a weighted sum. The image comparison portion determines that the two images do not match when the weighted sum exceeds a second threshold value.

Abstract: A method of manufacturing a group III nitride crystal according to a first aspect includes: preparing a seed substrate; generating a group III element oxide gas; supplying the group III element oxide gas; supplying a nitrogen element-containing gas; supplying an oxidizing gas containing nitrogen element containing at least one selected from the group consisting of NO gas, NO2 gas, N2O gas, and N2O4 gas; and growing the group III nitride crystal on the seed substrate.

Abstract: A group-III nitride substrate includes: a first region having a first impurity concentration in a polished surface; and a second region having a second impurity concentration lower than the first impurity concentration in the polished surface, wherein a first dislocation density of the first region is lower than a second dislocation density of the second region.

Abstract: A method of manufacturing a group-III nitride crystal includes: preparing a seed substrate; and supplying a group-III element oxide gas and a nitrogen element-containing gas at a supersaturation ratio (Po/Pe) greater than 1 and equal to or less than 5, then, growing a group-III nitride crystal on the seed substrate, wherein the Po is a supply partial pressure of the group-III element oxide gas, and the Pe is an equilibrium partial pressure of the group-III element oxide gas.

Abstract: A group-III nitride substrate includes: a first region having a first impurity concentration in a polished surface; and a second region having a second impurity concentration lower than the first impurity concentration in the polished surface, wherein a first dislocation density of the first region is lower than a second dislocation density of the second region.

Abstract: A group III nitride crystal, wherein the group III nitride crystal is doped with an N-type dopant and a hydrogen element, and the concentration of the N-type dopant is 1×1020 cm?3 or more, and the concentration of the hydrogen element is 1×1019 cm?3 or more.

Abstract: A group III nitride crystal, wherein the group III nitride crystal is doped with an N-type dopant and a germanium element, the concentration of the N-type dopant is 1×1019 cm?3 or more, and the concentration of the germanium element is nine times or more higher than the concentration of the N-type dopant.

Abstract: A group Ill nitride crystal manufacturing apparatus includes a raw material chamber generating a group Ill elemental oxide gas, and a growth chamber allowing the group Ill element oxide gas supplied from the raw material chamber to react with a nitrogen element-containing gas to generate a group III nitride crystal on a seed substrate, and the growth chamber incudes a decomposition promoting part promoting decomposition of the unreacted nitrogen element- containing gas between the seed substrate and an exhaust port for discharging the unreacted group Ill oxide gas and the nitrogen element-containing gas.

Abstract: A method of manufacturing a group III nitride crystal includes: preparing a seed substrate; causing surface roughness on the surface of the seed substrate; and supplying a group III element oxide gas and a nitrogen element-containing gas to grow a group III nitride crystal on the seed substrate.

Abstract: A group-III nitride substrate includes: a base material part of a group-III nitride including a front surface, a back surface, and an inner layer between the front surface and the back surface, wherein the carbon concentration of the front surface of the base material part is higher than the carbon concentration of the inner layer.

Abstract: A method of manufacturing a group-III nitride crystal includes: preparing a seed substrate; and supplying a group-III element oxide gas and a nitrogen element-containing gas at a supersaturation ratio (Po/Pe) greater than 1 and equal to or less than 5, then, growing a group-III nitride crystal on the seed substrate, wherein the Po is a supply partial pressure of the group-III element oxide gas, and the Pe is an equilibrium partial pressure of the group-III element oxide gas.

Abstract: A method of manufacturing a group III nitride crystal according to a first aspect includes: preparing a seed substrate; generating a group III element oxide gas; supplying the group III element oxide gas; supplying a nitrogen element-containing gas; supplying an oxidizing gas containing nitrogen element containing at least one selected from the group consisting of NO gas, NO2 gas, N2O gas, and N2O4 gas; and growing the group III nitride crystal on the seed substrate.

Abstract: A group III nitride crystal, wherein the group III nitride crystal is doped with an N-type dopant and a germanium element, the concentration of the N-type dopant is 1×1019 cm?3 or more, and the concentration of the germanium element is nine times or more higher than the concentration of the N-type dopant.

Abstract: A group III nitride crystal, wherein the group III nitride crystal is doped with an N-type dopant and a hydrogen element, and the concentration of the N-type dopant is 1×1020 cm?3 or more, and the concentration of the hydrogen element is 1×1019 cm?3 or more.

Abstract: A method of manufacturing a group-III nitride crystal includes: preparing a seed substrate; and supplying a group-III element oxide gas and a nitrogen element-containing gas at a supersaturation ratio (Po/Pe) greater than 1 and equal to or less than 5, then, growing a group-III nitride crystal on the seed substrate, wherein the Po is a supply partial pressure of the group-III element oxide gas, and the Pe is an equilibrium partial pressure of the group-III element oxide gas.

Abstract: A group-III nitride substrate includes: a first region having a first impurity concentration in a polished surface; and a second region having a second impurity concentration lower than the first impurity concentration in the polished surface, wherein a first dislocation density of the first region is lower than a second dislocation density of the second region.

Abstract: A method of manufacturing a group-III nitride crystal includes: preparing a seed substrate; and supplying a group-III element oxide gas and a nitrogen element-containing gas at a supersaturation ratio (Po/Pe) greater than 1 and equal to or less than 5, then, growing a group-III nitride crystal on the seed substrate, wherein the Po is a supply partial pressure of the group-III element oxide gas, and the Pe is an equilibrium partial pressure of the group-III element oxide gas.

Abstract: A group-III nitride substrate includes: a base material part of a group-III nitride including a front surface, a back surface, and an inner layer between the front surface and the back surface, wherein the carbon concentration of the front surface of the base material part is higher than the carbon concentration of the inner layer.