Optical properties of ZnxCd1-xS mixed-crystal thin film produced by PLD

Thin film of ZnxCd1-xS mixed crystal is applicable to short-wavelength optical devices from visible to UV region because of various band gaps. Using the pulsed laser deposition (PLD) method, we first produced the ZnxCd1-xS mixed crystal thin films. The surface morphology, the composition x and the crystal structure of the thin films were observed with SEMI EDAX and XRD respectively. The lattice constant corresponding to (002) plane of hexagonal crystal linearly depends on x following the Vegard's law. The crystal grains of the ZnxCd1-xS thin films have the c-axis perpendicular to the film surface and good crystallinity. The optical transmittance was measured at room temperature so that the optical, band gaps of direct transition continuously increase from 2.43 eV (5 10 rim) to 3.63 eV (340 rim) with x. The continuous change of the band gap indicates solid solution formation.