Fabrication of magnesium-doped gallium nitride nanorods and microphotoluminescence characteristics

High density magnesium (Mg)-doped gallium nitride (GaN) nanorods were fabricated by inductively coupled plasma reactive ion etching technique from the epitaxial film. Under the fixed Cl2∕Ar flow rate of 10∕25SCCM (SCCM denotes cubic centimeter per minute at STP) and inductively coupled plasma/bias power of 200∕200W, the nanorods were fabricated with a density of 108–1010cm2 and dimension of 20–100nm by varying the chamber pressure from 10to30mTorr. A large blueshift was observed in the photoluminescence (PL) peak energy of Mg-doped GaN nanorods under HeCd laser (325nm) excitation. The PL spectra of nanorods show a typical donor-acceptor-pair emission around 3.0eV with a large blueshift compared to the Mg-doped GaN film. The blueshift energy increases from 8to67meV as the excitation intensity varies from 12to56kW∕cm2. Possible reasons causing the power dependence of spectral shift in the PL emission energy are discussed.