Paper TF-WeA9
Optical Properties and Structure of Magnetron Sputtered Vanadium Oxide Thin Films

Wednesday, October 22, 2008, 4:20 pm, Room 302

Vanadium oxide (VO_x) thin films have been used for the last twenty years as the imaging material in uncooled infrared imaging devices. The important material properties for this application are a high thermal coefficient of resistance (TCR), controllable resistivity (ρ), low electrical noise and process compatibility with standard IC fabrication. In this work, device quality VO_x thin films have been fabricated by single and dual-target pulsed dc magnetron sputtering. The deposition parameters of this novel technique include vanadium (V), vanadium dioxide (VO₂), or vanadium trioxide (V₂O₃) sputter targets which can be used individually or two targets simultaneously with separately variable power, variable total pressure, variable oxygen partial pressure, and variable substrate temperature. Variations in these parameters have been shown to result in films with TCR between 1.5 and 4.0 (-%/K ) and ρ ranging from 0.1-100,000 Ω cm as measured by a four-point probe technique. The films produced in the region of device interest have been characterized with a wide variety of ex situ techniques to establish what role the deposition parameters play in the final structure and composition of the film, and the resulting effects of these characteristics on the electronic transport and optical properties. Transmission Electron Microscopy (TEM), Rutherford Backscattering (RBS), and Spectroscopic Ellipsometry (SE) have been used to characterize the nanocrystalline structure of these films, their bonding structure, the oxygen content in the film, and the dielectric function spectra (ε = ε₁ + ε₂) in the visible range (0.75-6.5 eV), respectively. By utilizing these complementary techniques, correlations between changes in the microstructure and composition determined by TEM and RBS, optical properties determined by SE, and electronic transport properties have been established.