Electronic and optical properties of La-aluminate dielectric thin films on Si (100)

摘要

Electronic and optical properties of (La_2O_3) _x(Al_2O_3)_(1-x) thin films grown on Si(100) by the atomic layer deposition method were studied by means of reflection electron energy loss spectroscopy (REELS). The dielectric function ε(k, ω), index of refraction (n) and the extinction coefficient (k) for (La_2O_3)_x(Al_2O_3) _(1-x) thin films were obtained from a quantitative analysis of REELS data. The band gap of (La_2O_3)_x(Al _2O_3)_(1-x) thin films increases from 5.75 to 6.35 eV as the Al_2O_3 content (1 - x) increases from 0.5 to 0.75 in the compound. The optical properties described in terms of n, k, and ε of (La_2O_3)_x(Al_2O_3) _(1-x) were obtained from REELS spectra by using QUEELS-ε(k, ω)-REELS software. They show that the electronic and optical properties of (La_2O_3)_x(Al_2O_3) _(1-x) thin films are dominated by La_2O_3 even for high Al_2O_3 concentrations.