Structural and optical study of Li doped CuO thin films on Si (100) substrate deposited by pulsed laser deposition

Abstract

• Cu 1 − x Li x O ( x = 0.0, 0.05, 0.07 and 0.09) thin films are successfully grown by PLD. • Raman and PL spectra confirm the single-phase formation of CuO thin films. • FESEM and AFM show that the grain size of Cu 1 − x Li x O thin films is ∼35 to 79 nm. • A reduction in optical band gap is observed from 2.99 to 2.76 eV for x = 0 to 0.09. In the present study, we report structural and optical properties of Cu 1 − x Li x O thin films grown on Si (1 0 0) substrates by pulsed laser deposition at different doping concentrations ( x = 0.0, 0.05, 0.07 and 0.09). The XRD spectra indicates the formation of polycrystalline CuO thin films and the crystallite size, calculated through XRD data is found to be increased from 7 to 14 nm for the samples with x = 0 to 0.09, respectively. FESEM analysis shows that the average size of Cu 1 − x Li x O nanostructures increases from 47 to 97 nm and AFM analysis also shows that the average size of Cu 1 − x Li x O nanostructures increases from 35 to 79 nm by increasing the Li doping concentrations from x = 0 to 0.09, respectively. Energy dispersive X-ray analysis with elemental mapping of the Li-doped CuO thin films shows that the Li dopants are incorporated homogeneously into the CuO thin film matrix. Moreover, Raman and photoluminescence spectra also confirm the single-phase formation of CuO thin films. A significant reduction in optical energy band gap is observed from 2.99 to 2.76 eV with an increase of Li concentration from 0 to 9%, respectively.