Sequential pulsed laser deposition of CdxZn1-xO alloy thin films for engineering ZnO band gap

Alloy thin films of CdxZn1-xO with different Cd concentrations were grown by sequential ablation of ZnO and CdO targets alternately, using a third-harmonic Q-switched Nd:YAG laser. The Cd concentration in the films, measured by Rutherford back scattering, was varied by controlling the ablation time of the CdO target relative to that of the ZnO. The films were found to be of a highly c-axis-oriented wurtzite phase with high crystalline quality, up to a Cd concentration of approximately 8%, beyond which CdO segregation occurred. The band gap of the CdxZn1-xO thin films was found to decrease monotonically from approximately 3.3 eV to approximately 2.9 eV with increasing x until the onset of CdO segregation.