Synthesis of GaN Cauliflower-like Nanostructures via Plasma Enhanced-CVD

Abstract

Specific physical and optical properties of gallium nitride (GaN) nanostructure such as, large breakdown electric field, large direct band gap, high thermal conductivity and high electron mobility, turn it to a highly promising semiconductor for microelectronic and optoelectronic devices. GaN cauliflower-like nanostructures (CLNs) were synthesized by direct current plasma enhanced chemical vapor deposition (PECVD). Gallium (Ga) metal and nitrogen plasma were used as precursors. The GaN CLNs were grown based on the direct reaction between Ga atoms and excited nitrogen species in the plasma environment on Si substrate. The results of X-ray diffraction (XRD) show that the grown GaN CLNs have the hexagonal wurtzite type structure. FE-SEM image indicates that the average grain size of the grown CLNs is ∼ 20nm. The photoluminescence (PL) measurements indicate that the band gap of GaN CLNs is 3.41eV. The EDS results show that the Ga and N ratio in the grown sample is 88% and 12%, respectively, by weight percent which is very close to the Ga and N ratio of prefect GaN crystal. The small Ga enrichment is related to the nitrogen vacancy of samples. The results demonstrate a simple inexpensive method for GaN CLNs formation at low temperature which is critical for many applications.