A nano-scale device and method of fabrication provide a nanowire having (111) vertical sidewalls. The nano-scale device includes a semiconductor-on-insulator substrate polished in a [110] direction, the nanowire, and an electrical contact at opposite ends of the nanowire. The method includes wet etching a semiconductor layer of the semiconductor-on-insulator substrate to form the nanowire extending between a pair of islands in the semiconductor layer. The method further includes depositing an electrically conductive material on the pair of islands to form the electrical contacts. A nano-pn diode includes the nanowire as a first nano-electrode, a pn-junction vertically stacked on the nanowire, and a second nano-electrode on a (110) horizontal planar end of the pn-junction. The nano-pn diode may be fabricated in an array of the diodes on the semiconductor-on-insulator substrate.