Abstract: The present invention relates to a support for the epitaxy of a layer of a material of composition AlxInyGa(1-x-y)N, where 0?x?1, 0?y?1 and x+y?1, having successively from its base to its surface; a support substrate, a bonding layer, a monocrystalline seed layer for the epitaxial growth of the layer of material AlxInyGa(1-x-y)N. The support substrate is made of a material that presents an electrical resistivity of less than 10?3 ohm·cm and a thermal conductivity of greater than 100 W·m?1·K?1. The seed layer is in a material of the composition AlxInyGa(1-x-y)N, where 0?x?1, 0?y?1 and x+y?1. The seed and bonding layers provide a specific contact resistance that is less than or equal to 0.1 ohm·cm?2, and the materials of the support substrate, the bonding layer and the seed layer are refractory at a temperature of greater than 750° C. or even greater than 1000° C. The invention also relates to methods for manufacturing the support.

Abstract: Composite substrates are produced that include a strained III-nitride material seed layer on a support substrate. Methods of producing the composite substrate include developing a desired lattice strain in the III-nitride material to produce a lattice parameter substantially matching a lattice parameter of a device structure to be formed on the composite substrate. The III-nitride material may be formed with a Ga polarity or a N polarity. The desired lattice strain may be developed by forming a buffer layer between the III-nitride material and a growth substrate, implanting a dopant in the III-nitride material to modify its lattice parameter, or forming the III-nitride material with a coefficient of thermal expansion (CTE) on a growth substrate with a different CTE.