The influence of laser wavelength on the structure, morphology, and photoluminescence properties of pulsed laser deposited CaS: Eu2+ thin films

摘要

Europium-doped calcium sulfide thin films were grown on Si (100) substrates using the pulsed laser deposition technique. The influence of the laser wavelength on the structure, morphology, and photoluminescent properties of the films was studied. The X-ray diffraction data showed that the films were amorphous, except for the (200) diffraction peak observed from the films deposited at the wavelengths of 266 and 355 nm. The atomic force microscopy and Rutherford backscattering spectroscopy data showed that the film deposited at 355 nm was rougher and thicker than those deposited at 266 and 532 nm. As a result, the highest photoluminescence emission intensity around 650 nm was observed from the film deposited at 355 nm. This emission was attributed to the 4f(6)5d(1) -> 4f(7)Eu(2+) transitions of Eu2+ observed. These films were evaluated for blue light-emitting diodes.