All the diffraction peaks are indexed to the hexagonal phase of ZnO (JCPDS 36-1451) and no other crystalline phases are detected.
The Raman spectra are sensitive to crystallization, structural disorder, and defects in micro- and nanostructures. As shown in Fig. 1b, the presence of a sharp and strong non-polar optical phonon E2H mode at 438 cm− 1 confirms that the products formed are wurtzite hexagonal ZnO.
Two very small peaks at 332 and 376 cm− 1 were also obtained which were assigned as E2H–E2L (multi-phonon)
and A1T modes, respectively [12].