Published online by Cambridge University Press: 01 February 2011
A new method to synthesize highly luminescent GaN:Mg powders has been developed. This method has a high control over the concentration of magnesium in the final product. The method consists of reacting a high purity (99.999 %) galliummagnesium alloy with ultra-high purity ammonia in a horizontal quartz tube reactor at high temperatures for several hours. Electron microscopy showed that the light-gray powders produced by this method consist of at least two different shaped crystallites; large columnar crystals sized around 10 μm and small platelets crystals between 1 and 2 μm. X-ray diffraction showed that those crystallites have a well defined wurtzite structure. Room temperature photoluminescence (PL) and cathodoluminescence (CL) showed a high intensity blue emission around 2.94 eV (422 nm). At helium temperature the well known Mg-related donor-acceptor pair band was observed at 3.25 eV (380 nm) by PL and CL.