MBE-deposited iridium silicides for focal plane array applications
AuthorLange, Davis Alan, 1964-
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractIridium silicides are of current interest as candidate detector materials for silicon based, Schottky-barrier infrared focal plane arrays. In this work, the growth and structure of codeposited IrSi₃ and Ir₃Si₄ films is discussed as well as the effect of annealing and deposition temperature on pure Ir film depositions. Nearly single-phase polycrystalline IrSi₃ films were formed by codeposition of Ir and Si in a 1:3 ratio at temperatures as low as 450°C. Localized epitaxial crystallite growth, identified by x-ray and electron diffraction, is found for IrSi₃ films formed at temperatures >600 °C, with a previously unreported c-axis epitaxial crystallite growth on Si(111) dominating at ∼700 °C. Single-phase polycrystalline Ir₃Si₄ films were formed by annealing room temperature 3:4 codeposited films, whereas localized epitaxial Ir₃Si₄ crystallite growth occurred for codeposition at temperatures of ∼500 °C. Annealed Ir films initially form IrSi crystallites at temperatures of ∼350 °C and further react with the substrate to form polycrystalline Ir₃Si5 at temperatures ≥ 550 °C. The Ir₃Si₄ phase, not found in annealed reactions, dominated the growth of silicide films formed by hot Ir depositions at 500 °C. A previously unreported Ir₃Si₄ epitaxial growth was identified for Ir depositions on Si(111)substrates. Resistivity measurements indicate that IrSi₃, IrSi, and Ir₃Si₄ films are metallic, where Ir₃Si₄ had the lowest resistivity of ∼60 μΩ-cm. Optical photoresponse and I-V measurements performed on diode structures indicate the barrier height of IrSi₃ on p-type Si(111) (∼0.33 eV) to be higher than that on p-type Si(100) (∼0.22-0.25 eV), limiting infrared imaging capability to the SWIR (1-3 μm) and MWIR (3-5 μm) atmospheric transmission windows, respectfully. Codeposited Ir₃Si₄ films display optical barrier heights between 0.125 to 0.175 eV on p-type Si(100), providing possible imaging capability in the LWIR (8-12 μm) spectral region. Ir₃Si₄ devices, displaying localized epitaxial crystallite growth, yield higher emission efficiency than polycrystalline Ir₃Si₄ films. Optical photoresponse measurements on a IrSi device also indicate a low optical barrier height (∼0.12 eV) providing access to the LWIR spectral region. Optical measurements on Ir₃Si5 films are also presented.
Degree ProgramGraduate College