In situ plume-emission monitoring during pulsed-laser deposition of YBa2Cu3O7−δ and yttria-stabilized zirconia thin films

A visible (optical) emission spectroscopy system has been developed as an in situ monitor for pulsed-laser deposition (PLD) of metal-oxide thin films, including YBa2Cu3O7−δ and yttria-stabilized zirconia, onto various substrates including silicon wafers. The spectrometer consists of a fiber-optic transfer to a diffraction grating and charge-coupled device (CCD) array, that provides spectroscopy with about 1.3 nm of resolution from 410 to 640 nm. The optical-emission spectral-refresh rate is limited to about 2 Hz, due to the operational requirements of the CCD and the digital converter. This is, however, sufficiently fast relative to film deposition rates that the quality of the plume can be usefully assessed during the complete film-deposition period, i.e., an in situ process monitor for PLD. Dependence of the emission plume spectra on distance from the target, laser energy density, ambient oxygen pressure, and in one case, target cation composition have all been measured.