More Like this

1. Magnesium sulfide powder analyzed by XPS

   https://doi.org/10.1116/6.0004185  

   Jäggi, Noah; Dukes, Catherine_A (January 2025, Surface Science Spectra)

   High-purity niningerite (MgS) was synthesized by BenchChem under vacuum conditions for use in laboratory simulations of solar-ion space weathering of sulfide minerals that are expected to be present on the surface of Mercury. MgS was initially characterized via x-ray photoelectron spectroscopy prior to investigations into the preferential loss of near-surface sulfur in niningerite with 2 keV H2+ irradiation. Survey and high-resolution (Mg 1s, Mg 2p, S 2p) x-ray photoelectron spectra of as-received magnesium sulfide powder (99.9%) are presented, including surface contaminants that originate from exposure to atmosphere (C 1s, O 1s). Minor impurities derived from sample synthesis (Al 2s, Al 2p) and packaging or processing (F 1s) are noted in the survey spectrum. 

   more » « less
2. Review–On Epitaxial Electrodeposition of Co, Cu, and Ru for Interconnect Applications

   https://doi.org/10.1149/1945-7111/ac8771  

   Barmak, Katayun; Gusley, Ryan R. (August 2022, Journal of The Electrochemical Society)

   Epitaxial electrodeposition of Co, Cu and Ru is compared and contrasted. The seed layer for electrodeposition of all three metals was an epitaxial Ru(0001) film that was deposited at an elevated temperature onto a sapphire(0001) substrate and annealed post deposition. The epitaxial orientation relationship of the electrodeposited film and the seed layer, the epitaxial misfit strain, the role of symmetry of the seed layer versus the electrodepositing layer is addressed. In addition, the impact of underpotential deposition on film nucleation, and the growth morphology of the films is discussed. It is shown that epitaxial electrodeposition of metallic films to thicknesses of tens of nanometers is readily achievable. This paper 1189 was presented during the 241st Meeting of the Electrochemical Society, May 29–June 2, 2022. 

   more » « less
3. Bulk-like dielectric and magnetic properties of sub 100 nm thick single crystal Cr2O3 films on an epitaxial oxide electrode

   https://doi.org/10.1038/s41598-020-71619-1  

   Vu, N. M.; Luo, X.; Novakov, S.; Jin, W.; Nordlander, J.; Meisenheimer, P. B.; Trassin, M.; Zhao, L.; Heron, J. T. (December 2020, Scientific Reports)

   null (Ed.)

   Abstract The manipulation of antiferromagnetic order in magnetoelectric Cr 2 O 3 using electric field has been of great interest due to its potential in low-power electronics. The substantial leakage and low dielectric breakdown observed in twinned Cr 2 O 3 thin films, however, hinders its development in energy efficient spintronics. To compensate, large film thicknesses (250 nm or greater) have been employed at the expense of device scalability. Recently, epitaxial V 2 O 3 thin film electrodes have been used to eliminate twin boundaries and significantly reduce the leakage of 300 nm thick single crystal films. Here we report the electrical endurance and magnetic properties of thin (less than 100 nm) single crystal Cr 2 O 3 films on epitaxial V 2 O 3 buffered Al 2 O 3 (0001) single crystal substrates. The growth of Cr 2 O 3 on isostructural V 2 O 3 thin film electrodes helps eliminate the existence of twin domains in Cr 2 O 3 films, therefore significantly reducing leakage current and increasing dielectric breakdown. 60 nm thick Cr 2 O 3 films show bulk-like resistivity (~ 10 12 Ω cm) with a breakdown voltage in the range of 150–300 MV/m. Exchange bias measurements of 30 nm thick Cr 2 O 3 display a blocking temperature of ~ 285 K while room temperature optical second harmonic generation measurements possess the symmetry consistent with bulk magnetic order. 

   more » « less
4. Demonstration of nearly pinhole-free epitaxial aluminum thin films by sputter beam epitaxy

   https://doi.org/10.1038/s41598-020-74981-2  

   Law, Ka Ming; Budhathoki, Sujan; Ranjit, Smriti; Martin, Franziska; Thind, Arashdeep S.; Mishra, Rohan; Hauser, Adam J. (December 2020, Scientific Reports)

   null (Ed.)

   Abstract Superconducting resonators with high quality factors have been fabricated from aluminum films, suggesting potential applications in quantum computing. Improvement of thin film crystal quality and removal of void and pinhole defects will improve quality factor and functional yield. Epitaxial aluminum films with superb crystallinity, high surface smoothness, and interface sharpness were successfully grown on the c-plane of sapphire using sputter beam epitaxy. This study assesses the effects of varying substrate preparation conditions and growth and prebake temperatures on crystallinity and smoothness. X-ray diffraction and reflectivity measurements yield extensive Laue oscillations and Kiessig thickness fringes for films grown at 200 °C under 15 mTorr Ar, indicating excellent crystallinity and surface smoothness; moreover, an additional substrate preparation procedure which involves (1) a modified substrate cleaning procedure and (2) prebake at 700 °C in 20 mTorr O 2 is shown by atomic force microscopy to yield nearly pinhole-free film growth while maintaining epitaxy and high crystal quality. The modified cleaning procedure is environmentally friendly and eliminates the acid etch steps common to conventional sapphire preparation, suggesting potential industrial application both on standard epitaxial and patterned surface sapphire substrates. 

   more » « less
5. Effect of post-deposition annealing on crystal structure of RF magnetron sputtered germanium dioxide thin films

   https://doi.org/10.1116/6.0003960  

   Abed, Ahmad Matar; Peterson, Rebecca L (October 2024, Journal of Vacuum Science & Technology A)

   In this work, we demonstrate the growth and phase stabilization of ultrawide bandgap polycrystalline rutile germanium dioxide (GeO2) thin films. GeO2 thin films were deposited using RF magnetron sputtering on r-plane sapphire (Al2O3) substrates. As-deposited films were x-ray amorphous. Postdeposition annealing was performed at temperatures between 650 and 950 °C in an oxygen or nitrogen ambient. Annealing at temperatures from 750 to 950 °C resulted in mixed-phase polycrystalline films containing tetragonal (rutile) GeO2, hexagonal (α-quartz) GeO2, and/or cubic (diamond) germanium (Ge). When nitrogen was used as the anneal ambient, mixed GeO2 phases were observed. In contrast, annealing in oxygen promoted stabilization of the r-GeO2 phase. Grazing angle x-ray diffraction showed a preferred orientation of (220) r-GeO2 for all crystallized films. The combination of O2 annealing and O2 flux during growth resulted in r-GeO2 films with highly preferential alignment. Using electron microscopy, we observed an interfacial layer of hexagonal-oriented GeO2 with epitaxial alignment to the (11¯02) Al2O3 substrate, which may help stabilize the top polycrystalline r-GeO2 film. 

   more » « less