Photoluminescence and enhanced third order nonlinear optical properties of InZnO thin films

Abstract

We proposed the photoluminescence and third order nonlinear optical properties of indium doped zinc oxide (InZnO) thin films with various dopant concentrations. InZnO thin films were grown by simultaneous RF/DC magnetron sputtering technique with different DC power 2 W, 6 W, 8 W and 10 W respectively. The structural characterization and surface morphology of obtained thin films are characterized by XRD and SEM techniques. XRD results revealed that thin film quality is enhanced after doping indium in ZnO. The observed enhanced crystallite size from SEM images agreed with XRD results. In linear optical properties analysis, all ZnO thin films possess high optical transmittance in visible region. The resulted room temperature photoluminescence (RTPL) provided the deeply understanding of optical properties and defect states characteristics. Third order nonlinear optical properties of ZnO thin films were detected using femtosecond Z-scan technique. The domination of oxygen defects (Vo) from RTPL results prohibited direct photon transition in ZnO thin films. But, it leads to observed indirect two photon transition via intermediate defect levels. The self focusing to self defocusing transition when dopant concentration heavily increased also could be interesting result of indium heavily doped ZnO thin film. However, the magnitude of third order nonlinear optical absorption as well as refraction of all ZnO thin films is found to be relatively enhanced with dopant concentration.