Magneto-optical Kerr-effect studies on copper oxide thin films produced by atomic layer deposition on SiO2

This work demonstrates the sensitivity of magneto-optical Kerr-effect (MOKE) spectroscopy to ultra-thin nonmagnetic films using the example of copper oxide. The films with an effective thickness between 0.6 nm and 6 nm are produced by atomic layer deposition (ALD) on silicon oxide substrates based on the Cu(I) β-diketonate precursor [(nBu3P)2Cu(acac)] (acac = acetylacetonate) at a process temperature of 120 °C. The copper oxide films exhibit magneto-optical activity in the spectral ranges around 2.6 eV and above 4 eV. The evolution of the spectral features as a function of the number of ALD cycles is simulated numerically using the dielectric function and the Voigt constant of Cu2O as input parameters. The comparison between experimental and simulated MOKE spectra strengthens the conclusion drawn from spectroscopic ellipsometry studies that the thin film optical constants differ markedly from the bulk ones.