A semiconductor device, comprising a light emitting diode device, comprising: a plurality of first conductivity type semiconductor nanowire cores located over a support; an insulating mask layer located over the support, wherein the nanowire cores comprise semiconductor nanowires epitaxially extending from portions of a semiconductor surface of the support exposed through openings in the insulating mask layer; a plurality of semiconductor shells (3A, 3B, 3C, 23) extending over the respective nanowire cores, wherein each of the plurality of semiconductor shells (3A, 3B, 3C, 23) comprises at least one semiconductor interior shell (3A, 3C, 23) extending around the respective one of the plurality of the first conductivity type nanowire cores, and a second conductivity type semiconductor outer shell extending around the at least one semiconductor interior shell (3A, 3C, 23); an active region shell around each of the plurality of nanowire cores, a first electrode layer that contacts the second conductivity type semiconductor outer shell of the plurality of semiconductor shells (3A, 3B, 3C, 23) and extends into spaces between the semiconductor shells (3A, 3B, 3C, 23); and a semiconductor foot portion which extends under the first electrode and under the respective second conductivity type semiconductor outer shell on the insulating mask layer in the spaces between the plurality of semiconductor shells (3A, 3B, 3C, 23); and wherein each semiconductor interior shell (3A, 3C, 23) comprises a second conductivity type semiconductor interior shell (3A, 3C) located between the active region shell and the second conductivity type outer shell, and the at least one semiconductor interior shell (3A, 3C, 23) is connected to the semiconductor foot portion; characterized in that each second conductivity type semiconductor interior shell (3A, 3C) comprises a p-AlGaN inner shell having 5 atomic % or less aluminum and a p-AlGaN intermediate shell having more than 5 atomic % aluminum; each second conductivity type semiconductor outer shell comprises a p-GaN outer shell; each p-AlGaN intermediate shell is located between the p-GaN outer shell and one of the p-AlGaN inner shell or the active region shell; the semiconductor foot portion comprises a p-AlGaN foot portion of the p-AlGaN intermediate shell; and the p-AIGaN foot portion connects to the p-AlGaN intermediate shell under the p-GaN outer shell. a plurality of first conductivity type semiconductor nanowire cores located over a support; an insulating mask layer located over the support, wherein the nanowire cores comprise semiconductor nanowires epitaxially extending from portions of a semiconductor surface of the support exposed through openings in the insulating mask layer; a plurality of semiconductor shells (3A, 3B, 3C, 23) extending over the respective nanowire cores, wherein each of the plurality of semiconductor shells (3A, 3B, 3C, 23) comprises at least one semiconductor interior shell (3A, 3C, 23) extending around the respective one of the plurality of the first conductivity type nanowire cores, and a second conductivity type semiconductor outer shell extending around the at least one semiconductor interior shell (3A, 3C, 23); an active region shell around each of the plurality of nanowire cores, a first electrode layer that contacts the second conductivity type semiconductor outer shell of the plurality of semiconductor shells (3A, 3B, 3C, 23) and extends into spaces between the semiconductor shells (3A, 3B, 3C, 23); and a semiconductor foot portion which extends under the first electrode and under the respective second conductivity type semiconductor outer shell on the insulating mask layer in the spaces between the plurality of semiconductor shells (3A, 3B, 3C, 23); and wherein each semiconductor interior shell (3A, 3C, 23) comprises a second conductivity type semiconductor interior shell (3A, 3C) located between the active region shell and the second conductivity type outer shell, and the at least one semiconductor interior shell (3A, 3C, 23) is connected to the semiconductor foot portion; characterized in that each second conductivity type semiconductor interior shell (3A, 3C) comprises a p-AlGaN inner shell having 5 atomic % or less aluminum and a p-AlGaN intermediate shell having more than 5 atomic % aluminum; each second conductivity type semiconductor outer shell comprises a p-GaN outer shell; each p-AlGaN intermediate shell is located between the p-GaN outer shell and one of the p-AlGaN inner shell or the active region shell; the semiconductor foot portion comprises a p-AlGaN foot portion of the p-AlGaN intermediate shell; and the p-AIGaN foot portion connects to the p-AlGaN intermediate shell under the p-GaN outer shell.