In-Situ Optical Diagnostics During Pulsed-Laser Deposition of Magnetoresistive La-Ca-Mn-O Films on Silicon Substrates
AbstractDuring pulsed-laser deposition of La0.67Ca0.33MnO3 films on silicon substrates, a system that consists of visible optical-emission spectroscopy (OES) and Fourier transform infrared (FT-IR) spectroscopy is employed to perform in-situ diagnosis of the laser-induced plume and to monitor the substrate temperature and the film thickness. The effects of oxygen pressure, laser fluence, and distance from the target surface on emission spectra were studied. In FT-IR measurements, the slopes of the reflectance versus wavenumber curves were observed to increase with film thickness and hence with time, which provides end-point detection during the film growth. La0.67Ca0.33MnO3 films with (100), (110), and mixed orientations, depending on the substrate temperature, were deposited on yttria-stabilized zirconia (YSZ) buffered Si(100) and Si(111) substrates. In a magnetic field of 5 T, the maximum magnetoresistance (MR) values of 250% at 195 K and 164% at 140 K were observed in the as-deposited (110) and (100) films, respectively.