Relaxed wurtzite ingan layers

A semiconductor structure comprising:

• (a) a first relaxed In-containing III-nitride layer comprising a first In-containing III-nitride surface is characterized by a first InN mole fraction and a first relaxed in-plane a-lattice parameter;
• and
• (b) a second relaxed In-containing III-nitride layer overlying the first relaxed In-containing III-nitride layer, wherein the second relaxed In-containing III-nitride layer is characterized by a second InN mole fraction and a second relaxed in-plane a-lattice parameter, wherein
• the second InN mole fraction is different than the first InN mole fraction;
• and
• the second relaxed in-plane a-lattice parameter is different that the first relaxed in-plane a-lattice parameter;
• and
• each of the first relaxed In-containing III-nitride layer and the second relaxed In-containing III-nitride layer is independently characterized by:
• (i) a surface roughness less than 1 nm RMS over a 1 μm×1 μm area;
• (ii) an in-plane a-lattice parameter within ±0.1% of a fully relaxed in-plane a-lattice parameter of the In-containing III-nitride material;
• and
• (iii) a substantially homogeneous InN mole fraction across at least a 1 μm×1 μm area of the relaxed In-containing III-nitride surface, wherein a deviation of the InN mole fraction is less than ±1% with respect to an average InN mole fraction of the relaxed In-containing III-nitride material.