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All-ALD Hafnia and Ferrite-Based Multiferroics for CMOS-Compatible Tunable Microwave Applications

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Technical Report,01 Oct 2017,30 Jun 2018

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EpoXtal LLC Philadelphia United States

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Major Goals 1 Demonstrate the feasibility of a commercial deposition process for a multi-ferroic multilayer film by first demonstrating deposition by scalable processes separately for high quality ferroelectric and ferromagnetic thin films on substrates compatible with CMOS processing. The deposition process and any postdeposition processing must be compatible with CMOS processing. In general, this will require the initial film deposition and subsequent processing steps including any annealing to be at temperatures below 450C. 2 Determine film quality by scanning electron microscopy, energy dispersive spectroscopy, x-ray diffractionx-ray reflectivity, atomic force microscopy and Rutherford backscattering. 3 Determine the dielectric loss tangent for the films separate from the substrate. Determine remnant and maximum polarization and coercive field of the ferroelectric film and saturation polarization of the magnetic film. 4 Demonstrate piezomagnetic coefficient of 5 ppmOe and magnetic loss tangent 5 at 1 GHz for the magnetic film and dielectric loss tangent of 1 for the ferroelectric film at room temperature. Accomplishments 1 We demonstrated the deposition of ferroelectric strontium-doped hafnia SHO and ferromagnetic cobalt ferrite CFO thin films by atomic layer deposition. Film thickness was varied between 10 and 50 nm. Strontium doping was varied between 2 and 10 at. CFO readily crystalized at deposition temperatures above 300 C, however we found the crystalization temperature of SHO was increased by higher Sr doping levels and that at 2 at, SHO crystalized above 500 C. 2 We characterized the quality of our SHO and CFO films by SEM, EDS, XRDXRR, AFM, and RBS. We grew SHO and CFO on bare 100 Si as well as 111 oriented Pt and polycrystaline TiN buffer layers and other substrates as well.

Subject Categories:

  • Solid State Physics
  • Properties of Metals and Alloys
  • Electricity and Magnetism

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