Second harmonic generation of fluorine-doped zinc oxide thin films grown on soda-lime glass substrates by a chemical spray technique

Second harmonic generation (SHG) studies of fluorine-doped zinc oxide (ZnO:F) thin films deposited on soda-lime glass substrates from an aged solution in conjunction with zinc pentanedionate, using the chemical spray deposition technique were carried out. The χ31(2) and χ33(2) independent tensorial components of the quadratic nonlinear optical susceptibility of the ZnO:F thin films were evaluated. Scanning electron microscopy and X-ray diffraction investigations revealed a homogeneous distribution of nanoparticles of similar size and morphology for various samples deposited at different substrate temperatures (ranging from 400 to 525 °C). The SHG-technique revealed a clear dependence of the nonlinear optical response with the deposition temperature. Typical optical transmittance and photoluminescence (PL) studies were also performed, from which a bandgap (Eg) of 3.3 eV was evaluated in films deposited under optimal conditions of conductivity and transmittance.