Role of Ga presence into the heterojunction of metal oxide semiconductor on the stability and tunability ZnO ceramics

Abstract

In this study we investigated the stability and tunability of Zn Ga O 1 x x ceramics obtained by using the pressureless solid state reaction method. Analysis based on XRD data showed that a smaller ionic radius of Ga atom helps to minimize stress in the lattice. Phase pure ceramics have been obtained with relatively good density up to 0.5% of Ga doping. Further doping resulted in a secondary phase of ZnGa O2 4 along the heterojunction with several physical defects. The presence of defect dipole resulted in complex dielectric polarization in the material. The Cole-Cole model of dielectric relaxation fitted well with the dielectric data where as the doped samples exhibited higher dielectric permittivities at lower frequencies. Doping also resulted in bigger semicircles into the Nyquist plots of the impedance data due to the higher grain boundary resistance. The Eg can be tuned to the lower values of the doped samples with respect to the pure ZnO samples. The possible energy conversion applications discussed here in the light of better stability and tunability of the material.