Photonic stop band effect in ZnO inverse photonic crystal

Three-dimensional photonic crystals are fabricated using inward-growing self-assembly technique from polymethyl methacrylate (PMMA) colloids. Their air voids are infiltrated with zinc oxide (ZnO) by sol-gel method and the PMMA template is removed by the two independent processes of heat treatment and wet chemical method resulting in ZnO inverse photonic crystal. The inversion is confirmed from the structural characterization. In X-ray diffraction (XRD) experiment, the ZnO inverse photonic crystals obtained by both the techniques do not show any signature of single-crystalline ZnO. The inverse photonic crystals obtained by chemical method are further heated at different temperatures and XRD confirms crystalline nature of ZnO for temperature treatment at 400 °C. Laser-induced emission studies on ZnO inverse photonic crystals are carried out at two different excitation wavelengths. Excitation with 355 nm enables the observation of the stop band effect for emission at 45° from the inverse crystal obtained by the inexpensive chemical method.