The invention relates to a two-dimensional crystal wafer of group 13 or III element nitride which is delimited by a face of orientation N, an opposing face of orientation E depending on the group 13 or III element, E being selected preferably from Ga, In, Al or a combination of these elements, characterized in that the variation in crystalline off-cut angle in the largest dimension of said wafer is less than 5×10-3°/mm, and its curvature of geometric deformation of its faces exhibits a flexure in terms of absolute value of less than 10-3 mm/mm of the largest dimension of said wafer.