The ability to control and modulate the composition(1-4), doping(1,3-5), crystal structure(6-8) and morphology(9,10) of semiconductor nanowires during the synthesis process has allowed researchers to explore various applications of nanowires(11-15). However, despite advances in nanowire synthesis, progress towards the ab initio design and growth of hierarchical nano-structures has been limited. Here, we demonstrate a 'nanotectonic' approach that provides iterative control over the nucleation and growth of nanowires, and use it to grow kinked or zigzag nanowires in which the straight sections are separated by triangular joints. Moreover, the lengths of the straight sections can be controlled and the growth direction remains coherent along the nanowire. We also grow dopant-modulated structures in which specific device functions, including p-n diodes and field-effect transistors, can be precisely localized at the kinked junctions in the nanowires.