A catalyst free method to grow GaN nanowires on porous Si at low temperature

Abstract

GaN nanowires (NWs) were synthesized on porous silicon (PSi) as a substrate using pulsed direct current plasma enhanced chemical vapor deposition (DC-PECVD) method at 600°C. The precursors were gallium (Ga) metal and nitrogen (N) plasma. The GaN NWs were grown as a result of direct reaction between Ga atoms and excited N atoms in the plasma environment on PSi substrate, without using any catalyst. Self-induced mechanism is suggested to grow GaN NWs on PSi. Characterizations of GaN NWs were carried out by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and Raman spectroscopy. These measurements showed that the hexagonal structure of GaN NWs were synthesized with diameters from 20 to 50nm. The band gap energy of GaN NWs was obtained about 3.42eV. Further optical analysis using Raman spectra displayed two Raman active optical phonons at 535cm−1 and 730cm−1 due to A1 (TO) and A1 (LO), respectively.