Nanostructures provide novel opportunities of studying epitaxy in nano/mesoscale and on nonplanar substrates. Epitaxial
growth of silicon (Si) on the surfaces of Si nanowires along radial direction is a promising way to prepare radial p-(i)-n
junction in nanoscale for optoelectronic devices. Comprehensive studies of Si radial epitaxy in micro/nanoscale reveal
that morphological evolution and size-dependent radial shell growth rate for undoped and doped Si radial shells. Single
crystalline Si radial p-i-n junction wire arrays were utilized to fabricate photovoltaic (PV) devices. The PV devices
exhibited the photoconversion efficiency of 10%, the short-circuit current density of 39 mA/cm2, and the open-circuit
voltage of 0.52 V, respectively.