Method for producing III-N templates and the reprocessing thereof and III-N template

A process for preparing a template for producing a III-N crystal, the template comprising a substrate and at least one III-N crystal layer, wherein the process comprises,

• a) selecting at least one group III element from the group consisting of Al, Ga and In;
• b) forming a III-N layer comprising the at least one selected group III element, on a substrate comprising sapphire;
• c) depositing a mask material that inhibits III-N growth as an interlayer on the III-N layer, wherein the interlayer is a discontinuous layer that, as viewed along a face surface of the template, the interlayer comprises nanometer-scale islands of mask material and microscopic and/or nanometer scale gaps lacking mask material;
• and
• d) growing a crystalline III-N material comprising the at least one selected group III element on the mask material, wherein the mask material,
• wherein the curvature Ks of the growth surface of the crystalline III-N material at a first, relatively earlier time point is greater than the curvature Ke at a second, relatively later time point;
• and
• the distance between the mask material and the substrate is at most 300 nm.