III nitride/foreign substrate composite template and preparation method thereof

The invention belongs to the technical field of material chemistry, and particularly relates to a III nitride/foreign substrate composite template and a preparation method thereof. The composite template comprises a substrate layer and an epitaxial layer. Nanoscale holes are arranged in the epitaxial layer. The epitaxial layer is made of III nitride. The III nitride material below the nanoscale hole layer contains Al element. Due to the nanoscale holes in the epitaxial layer, the defect density in the III nitride is effectively reduced. Cracks in the composite template are avoided. The III nitride/foreign substrate composite template and the preparation method thereof have the advantage of simple growth process, and are suitable for promotion.