Structural and electrical properties of tantalum oxide films grown by photo-assisted pulsed laser deposition

We describe the growth of thin films of Ta2O5 on quartz and silicon (100) substrates by an in situ photo-assisted pulsed laser deposition (photo-PLD) using radiation from a Nd:YAG laser (wavelength, lambda = 532 nm) to stimulate the ablation, and from an excimer lamp to excite additional photochemistry. The layers grown were investigated by Fourier transform infrared (FT-IR) spectroscopy, UV spectrophotometry, atomic force microscopy (AFM), ellipsometry and electrical measurements. We have found that they exhibit a significant improvement in microstructure, and optical and electrical properties compared with conventional PLD films prepared under, otherwise, identical conditions. For example, FT-IR results showed that the suboxide content in the as-grown films deposited by the photo-PLD process is less, while the leakage current density was an order of magnitude less at around 10(-6),A/cm(2) at a bias of 1 V. These results indicate that this photo-PLD process approach can be advantageous for dielectric and optical oxide film growth. (C) 2002 Elsevier Science B.V. All rights reserved.