46 research outputs found
Spin-Hall-Active Platinum Thin Films Grown Via Atomic Layer Deposition
We study the magnetoresistance of yttrium iron garnet/Pt heterostructures in
which the Pt layer was grown via atomic layer deposition (ALD).
Magnetotransport experiments in three orthogonal rotation planes reveal the
hallmark features of spin Hall magnetoresistance. We estimate the spin
transport parameters by comparing the magnitude of the magnetoresistance in
samples with different Pt thicknesses. We compare the spin Hall angle and the
spin diffusion length of the ALD Pt layers to the values reported for
high-quality sputter-deposited Pt films. The spin diffusion length of 1.5nm
agrees well with platinum thin films reported in the literature, whereas the
spin Hall magnetoresistance is
approximately a factor of 20 smaller compared to that of our sputter-deposited
films. Our results demonstrate that ALD allows fabricating spin-Hall-active Pt
films of suitable quality for use in spin transport structures. This work
provides the basis to establish conformal ALD coatings for arbitrary surface
geometries with spin-Hall-active metals and could lead to 3D spintronic devices
in the future.Comment: 11 pages, 3 figure
Advanced Silicon-on-Insulator: Crystalline Silicon on Atomic Layer Deposited Beryllium Oxide
Silicon-on-insulator (SOI) technology improves the performance of devices by reducing parasitic capacitance. Devices based on SOI or silicon-on-sapphire technology are primarily used in high-performance radio frequency (RF) and radiation sensitive applications as well as for reducing the short channel effects in microelectronic devices. Despite their advantages, the high substrate cost and overheating problems associated with complexities in substrate fabrication as well as the low thermal conductivity of silicon oxide prevent broad applications of this technology. To overcome these challenges, we describe a new approach of using beryllium oxide (BeO). The use of atomic layer deposition (ALD) for producing this material results in lowering the SOI wafer production cost. Furthermore, the use of BeO exhibiting a high thermal conductivity might minimize the self-heating issues. We show that crystalline Si can be grown on ALD BeO and the resultant devices exhibit potential for use in advanced SOI technology applications
Heat-transport mechanisms in molecular building blocks of inorganic/organic hybrid superlattices
Atomic-Level Structural and Electronic Properties of Hybrid Inorganic–Organic ZnO:Hydroquinone Superlattices Fabricated by ALD/MLD
Anticancer compound ABT-263 accelerates apoptosis in virus-infected cells and imbalances cytokine production and lowers survival rates of infected mice
Peer reviewe
Development of thermoelectric thin films and characterization methods
This work reports on the fabrication of thin films of inorganic thermoelectric materials like borides, germanides, manganese compounds, and characterization of their thermoelectric properties. We have utilized a unique high temperature molecular beam epitaxy (MBE) apparatus to grow hexaboride thin films and manganese germanides. Magnetic manganese based alloy thin films were also grown using sputtering, since we are interested in the possibilities of utilizing magnetism to develop thermoelectric materials.</p
Heat-transport mechanisms in molecular building blocks of inorganic/organic hybrid superlattices
Nanomaterial interfaces and concomitant thermal resistances are generally considered as atomic-scale planes that scatter the fundamental energy carriers. Given that the nanoscale structural and chemical properties of solid interfaces can strongly influence this thermal boundary conductance, the ballistic and diffusive nature of phonon transport along with the corresponding phonon wavelengths can affect how energy is scattered and transmitted across an interfacial region between two materials. In hybrid composites composed of atomic layer building blocks of inorganic and organic constituents, the varying interaction between the phononic spectrum in the inorganic crystals and vibronic modes in the molecular films can provide a new avenue to manipulate the energy exchange between the fundamental vibrational energy carriers across interfaces. Here, we systematically study the heat transfer mechanisms in hybrid superlattices of atomic- and molecular-layer-grown zinc oxide and hydroquinone with varying thicknesses of the inorganic and organic layers in the superlattices. We demonstrate ballistic energy transfer of phonons in the zinc oxide that is limited by scattering at the zinc oxide/hydroquinone interface for superlattices with a single monolayer of hydroquinone separating the thicker inorganic layers. The concomitant thermal boundary conductance across the zinc oxide interfacial region approaches the maximal thermal boundary conductance of a zinc oxide phonon flux, indicative of the contribution of long wavelength vibrations across the aromatic molecular monolayers in transmitting energy across the interface. This transmission of energy across the molecular interface decreases considerably as the thickness of the organic layers are increased.Peer reviewe