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 Cl-2/Ar flow rate of 10/25 SCCM (SCCM denotes cubic centimeter per minute at STP) and inductively coupled plasma/bias power of 200/200 W, the nanorods were fabricated with a density of 10(8)-10(10) cm(2) and dimension of 20-100 nm by varying the chamber pressure from 10 to 30 mTorr. A large blueshift was observed in the photoluminescence (PL) peak energy of Mg-doped GaN nanorods under HeCd laser (325 nm) excitation. The PL spectra of nanorods show a typical donor-acceptor-pair emission around 3.0 eV with a large blueshift compared to the Mg-doped GaN film. The blueshift energy increases from 8 to 67 meV as the excitation intensity varies from 12 to 56 kW/cm(2). Possible reasons causing the power dependence of spectral shift in the PL emission energy are discussed. 2006 American Vacuum Society.