A nanocolumn device comprising: an array of gallium-nitride (GaN) nanocolumns grown by Molecular Beam Epitaxy wherein each of the GaN nanocolumns comprises a first end that is negatively doped and a second end that is positively doped with a light emitting region between the first end and the second end; a layer of insulating material in contact and covering sidewall surfaces over a full length of each of the GaN nanocolumns, said full length extending over said first end, said second end and said light emitting region; and a layer of reflective material in contact with and covering said layer of insulating material to aid in guiding light in said nanocolumns to an exit window, and wherein light emitted from said light emitting region is guided in said nanocolumns to said first end and to said second end; said array of GaN nanocolumns having an interstitial filler material between said GaN nanocolumns; a common transparent contact covering the first ends of the array of GaN nanocolumns and providing said exit window for said light; a transmissive metal coating (75, 73) on the second ends of the array of GaN nanocolumns, said transmissive metal coating having a thickness sufficient to bond to the second ends of the array of GaN nanocolumns; an array of reflective conductive contacts each covering said transmissive metal coating (75, 73) of a number of said GaN nanocolumns representing a pixel or subpixel for reflecting said light to said exit window, wherein said transmissive metal coating provides reduced electric resistance between the positively doped second ends of the GaN nanocolumns and the reflective conductive contacts; and a driver semiconductor substrate having surface contacts connected to said array of reflective conductive contacts. an array of gallium-nitride (GaN) nanocolumns grown by Molecular Beam Epitaxy wherein each of the GaN nanocolumns comprises a first end that is negatively doped and a second end that is positively doped with a light emitting region between the first end and the second end; a layer of insulating material in contact and covering sidewall surfaces over a full length of each of the GaN nanocolumns, said full length extending over said first end, said second end and said light emitting region; and a layer of reflective material in contact with and covering said layer of insulating material to aid in guiding light in said nanocolumns to an exit window, and wherein light emitted from said light emitting region is guided in said nanocolumns to said first end and to said second end; a first end that is negatively doped and a second end that is positively doped with a light emitting region between the first end and the second end; a layer of insulating material in contact and covering sidewall surfaces over a full length of each of the GaN nanocolumns, said full length extending over said first end, said second end and said light emitting region; and a layer of reflective material in contact with and covering said layer of insulating material to aid in guiding light in said nanocolumns to an exit window, and wherein light emitted from said light emitting region is guided in said nanocolumns to said first end and to said second end; said array of GaN nanocolumns having an interstitial filler material between said GaN nanocolumns; a common transparent contact covering the first ends of the array of GaN nanocolumns and providing said exit window for said light; a transmissive metal coating (75, 73) on the second ends of the array of GaN nanocolumns, said transmissive metal coating having a thickness sufficient to bond to the second ends of the array of GaN nanocolumns; an array of reflective conductive contacts each covering said transmissive metal coating (75, 73) of a number of said GaN nanocolumns representing a pixel or subpixel for reflecting said light to said exit window, wherein said transmissive metal coating provides reduced electric resistance between the positively doped second ends of the GaN nanocolumns and the reflective conductive contacts; and a driver semiconductor substrate having surface contacts connected to said array of reflective conductive contacts.