Micro-Raman investigation of nanocrystalline GaN, AlN, and an AlGaN composite prepared from pyrolysis of metal amide-imide precursors

In this communication the impact of precursor pyrolysis temperature on the Raman spectroscopic properties of nanophase GaN derived from the polymeric gallium imide {Ga(NH)(3/2)}(n) is reported. GaN prepared by pyrolysis at either 900 or 1100 degrees C exhibits modes at ca. 570 and 730 cm(-1), consistent with the presence of hexagonal GaN. Employing a lower conversion temperature of 700 degrees C produces a lattice with extensive defects, as evidenced by the presence of additional bands at 332, 410, 637, and 744 cm(-1); additional heating of this type of sample at 900 or 1000 degrees C diminishes the intensity of these defect-related modes. Raman spectra of nanophase aluminum nitride (ALN) and an aluminum gallium nitride (AlGaN) composite prepared from pyrolysis of the requisite precursors at a fixed temperature of 900 degrees C are also presented.