Ferroelectronics Lab

Understanding and utilizing non-volatile properties of materials

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New Publication! Fully epitaxial ferroelectric ScAlN grown by molecular beam epitaxy

June 3, 2021 By Matt Webb

We report on the demonstration of ferroelectricity in ScxAl1-xN grown by molecular beam epitaxy on GaN templates. Distinct polarization switching is unambiguously observed for ScxAl1-xN films with Sc contents in the range of 0.14–0.36. Sc0.20Al0.80N, which is nearly lattice- matched with GaN, exhibiting a coercive field of ~ 4.2 MV/cm at 10 kHz and a remnant polarization of ~ 135 uC/cm2. After electrical poling, Sc0.20Al0.80N presents a polarization retention time beyond 105 s. No obvious fatigue behavior can be found with up to 3 x 105 switching cycles. The work reported here is more than a technical achievement. The realization of ferroelectric single-crystalline III–V semiconductors by molecular beam epitaxy promises a thickness scaling into the nanometer regime and makes it possible to integrate high-performance fer- roelectric functionality with well-established semiconductor platforms for a broad range of electronic, optoelectronic, and photonic device applications.

Full text available from Applied Physics Letters

Filed Under: Publications

New Publication! Engineering new limits to magnetostriction through metastability in iron-gallium alloys

May 17, 2021 By Matt Webb

Magnetostrictive materials transduce magnetic and mechanical energies and when combined with piezoelectric elements, evoke magnetoelectric transduction for high-sensitivity magnetic field sensors and energy-efficient beyond-CMOS technologies. The dearth of ductile, rare- earth-free materials with high magnetostrictive coefficients motivates the discovery of superior materials. Fe1−xGax alloys are amongst the highest performing rare-earth-free magnetostrictive materials; however, magnetostriction becomes sharply suppressed beyond x = 19% due to the formation of a parasitic ordered intermetallic phase. Here, we harness epitaxy to extend the stability of the BCC Fe1−xGax alloy to gallium compositions as high as x = 30% and in so doing dramatically boost the magnetostriction by as much as 10x relative to the bulk and 2x larger than canonical rare-earth based magnetostrictors. A Fe1−xGax − [Pb (Mg1/3Nb2/3)O3]0.7−[PbTiO3]0.3 (PMN-PT) composite magnetoelectric shows robust 90° electrical switching of magnetic anisotropy and a converse magnetoelectric coefficient of 2.0 × 10−5 s m−1. When optimally scaled, this high coefficient implies stable switching at ~80 aJ per bit.

Full text available from Nat Commun

Additionally see the report from The Michigan Engineering News Center ‘Harnessing the hum‘ and the report in Popular Science ‘How shape-shifting magnets could help build a lower-emission computer‘

Filed Under: Publications

Peter defends his PhD dissertation! Congratulations Peter!

March 24, 2021 By Matt Webb

Today, Peter gave a great defense of his PhD dissertation, titled “Disorder-Engineering of Ferroic Properties“. Congratulations Peter! The Ferroelectronics Lab wishes you the very best luck in your future work!

Filed Under: Graduate Student Progress

Sieun presents at APS March Meeting!

March 23, 2021 By Matt Webb

Sieun gave a virtual talk at the American Physical Society (APS) March Meeting last week. Congratulations! Her abstract is included below.

Epitaxial stabilization of rutile germanium oxide thin film by molecular beam epitaxy

Ultrawide-band-gap (UWBG) semiconductors have tantalizing advantages for power electronics. Materials such as AlN/AlGaN, β-Ga2O3, and diamond have been developed for UWBG semiconducting devices, however, they are still facing challenges, such as doping asymmetry and/or inefficient thermal conduction. Rutile GeO2 (r-GeO2) has been theoretically established to have an UWBG (4.68 eV), high electron and hole mobility (289 cm2 V-1s-1 and 28 cm2 V-1s-1), high thermal conductivity (51 W m–1 K–1) and ambipolar dopability. The synthesis of r-GeO2 thin films has not been reported but is critical to enable microelectronics applications. Here, we report the growth of single-crystalline r-GeO2 thin films on R-plane sapphire substrates using molecular beam epitaxy. We control the competing reactions between the deeply metastable glass phase formation and rutile phase formation as well as absorption and desorption by utilizing (1) a buffer layer with reduced lattice misfit, and (2) the growth condition that allows the condensation of the preoxidized molecular precursor yet provides sufficient adatom mobility. The findings advance the synthesis of single-crystalline films of materials prone to glass formation and provide opportunities to realize promising UWBG semiconductors.

Filed Under: Conferences

Peter has been selected as the 2021 MSE recipient of the Towner Prize for Distinguished Academic Achievement

March 16, 2021 By Matt Webb

The award recognizes the outstanding graduate student in each degree program. Prize criteria include a student’s active participation in research, leadership and academic performance (GPA). 

Congratulations Peter!

Filed Under: Awards

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News

  • New Publication! “Geometric defects induced by strain relaxation in thin film oxide superlattices.” November 10, 2022
  • New Publication! “Nanophotonic control of thermal emission under extreme temperatures in air” September 29, 2022
  • New Publication! “Germanium dioxide: A new rutile substrate for epitaxial film growth” September 1, 2022

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About

Our work is multidisciplinary. We employ concepts and tools from the fields of materials science, chemistry, physics and electrical engineering to develop new methods to investigate and engineer … Read More

News

New Publication! “Geometric defects induced by strain relaxation in thin film oxide superlattices.”

November 10, 2022 By Matt Webb

New Publication! “Nanophotonic control of thermal emission under extreme temperatures in air”

September 29, 2022 By Matt Webb

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Ferroelectronics Lab
Address: 2030 H.H. Dow

T: (734) 763-6914
E: jtheron@umich.edu
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