A structure comprising an epitaxial group-III-nitride buffer-layer structure between a silicon substrate and at least one active layer, wherein the buffer-layer structure comprises at least one stress management layer sequence (S) including an interlayer structure arranged between and adjacent to a first and a second group-III-nitride layer , wherein the interlayer structure comprises a group-III-nitride interlayer material having a larger band gap than the materials of the first and second group-III-nitride layers , and wherein a p-type-dopant-concentration profile drops, starting from at least 5×10 18 cm -3 , by at least a factor of two in transition from the interlayer structure to the first and second group-III-nitride layers , wherein the thickness of the first group-III-nitride layer is between 300 nm and 2000 nm, and the thickness of the second group-III-nitride layer , is between 300 nm and 1500 nm, wherein the dopant concentration of the first group-III-nitride layer and of the second group-III-nitride layer is not more than 1×10 17 cm -3 , wherein the dopant concentration throughout the interlayer structure is at least 5×10 18 cm -3 , the interlayer structure comprises three different layers, a first group-III-nitride interlayer arranged between and adjacent to a second and a third group-III-nitride interlayer , wherein the thickness is between 20 nm and 200 nm for second and a third group-III-nitride interlayer , the second and third group-III-nitride interlayers are made of GaN as well as the first and second group-III-nitride layers and wherein the first group-III-nitride interlayer consist of AlGaN and the first group-III-nitride interlayer comprises a constant aluminum content or comprises a gradient in the aluminum content increasing from the second group-III-nitride interlayer to the third group-III-nitride interlayer , wherein the second group-III-nitride interlayer is closer to the substrate than the third group-III-nitride interlayer . wherein the thickness of the first group-III-nitride layer is between 300 nm and 2000 nm, and the thickness of the second group-III-nitride layer , is between 300 nm and 1500 nm, wherein the dopant concentration of the first group-III-nitride layer and of the second group-III-nitride layer is not more than 1×10 17 cm -3 , wherein the dopant concentration throughout the interlayer structure is at least 5×10 18 cm -3 , the interlayer structure comprises three different layers, a first group-III-nitride interlayer arranged between and adjacent to a second and a third group-III-nitride interlayer , wherein the thickness is between 20 nm and 200 nm for second and a third group-III-nitride interlayer , the second and third group-III-nitride interlayers are made of GaN as well as the first and second group-III-nitride layers and wherein the first group-III-nitride interlayer consist of AlGaN and the first group-III-nitride interlayer comprises a constant aluminum content or comprises a gradient in the aluminum content increasing from the second group-III-nitride interlayer to the third group-III-nitride interlayer , wherein the second group-III-nitride interlayer is closer to the substrate than the third group-III-nitride interlayer . <EOS>