Optical Properties of Zn_xCd_(1-x)S Mixed Crystal Thin Film Produced by PLD

摘要

Thin film of Zn_xCd_(1-x)S 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 Zn_xCd_(1-x)S mixed crystal thin films. The surface morphology, the composition x and the crystal structure of the thin films were observed with SEM, 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 Zn_xCd_(1-x)S 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 (510 nm) to 3.63 eV (340 nm) with x. The continuous change of the band gap indicates solid solution formation.