A Novel Method to Fabricate Silicon Nanowire p-n Junctions by a Combination of Ion Implantation and in-situ Doping.

We demonstrate a novel method to fabricate an axial p-n junction inside <111> oriented short vertical silicon nanowires grown by molecular beam epitaxy by combining ion implantation with in-situ doping. The lower halves of the nanowires were doped in-situ with boron (concentration ~1018cm-3), while the upper halves were doubly implanted with phosphorus to yield a uniform concentration of 2 × 1019 cm-3. Electrical measurements of individually contacted nanowires showed excellent diode characteristics and ideality factors close to 2. We think that this value of ideality factors arises out of a high rate of carrier recombination through surface states in the native oxide covering the nanowires.