This work reports on the correlation between structure, surface/interface morphology and mechanical properties of pulsed laser deposited (PLD)
- Award ID(s):
- 2042638
- NSF-PAR ID:
- 10317853
- Date Published:
- Journal Name:
- Journal of Materials Research
- Volume:
- 37
- Issue:
- 1
- ISSN:
- 0884-2914
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract β -Ga2O3films on transparent quartz substrates. By varying the deposition temperature in the range of 25 °C–700 °C, ∼200 nm thick Ga2O3films with variable microstructure and amorphous-to-nanocrystalline nature were produced onto quartz substrates by PLD. The Ga2O3films deposited at room temperature were amorphous; nanocrystalline Ga2O3films were realized at 700 °C. The interface microstructure is characterized with a typical nano-columnar morphology while the surface exhibits the uniform granular morphology. Corroborating with structure and surface/interface morphology, and with increasing deposition temperature, tunable mechanical properties were seen in PLD Ga2O3films. At 700 °C, for nanocrystalline Ga2O3films, the dense grain packing reduces the elastic modulus Erwhile improving the hardness. The improved crystallinity at elevated temperatures coupled with nanocrystallinity, theβ -phase stabilization is accounted for the observed enhancement in the mechanical properties of PLD Ga2O3films. The structure-morphology-mechanical property correlation in nanocrystalline PLDβ -Ga2O3films deposited on quartz substrates is discussed in detail. -
This report is on the nature of strain in thin films of yttrium iron garnet (YIG) on yttrium aluminum garnet (YAG) substrates due to film-substrate lattice mismatch and the resulting induced magnetic anisotropy. Films with thickness 55 nm to 380 nm were deposited on (100), (110), and (111) YAG substrates using pulsed laser deposition (PLD) techniques and characterized by structural and magnetic characterization techniques. The in-plane strain determined to be compressive using X-ray diffraction (XRD). It varied from −0.12% to −0.98% and increased in magnitude with increasing film thickness and was relatively large in films on (100) YAG. The out-of-plane strain was tensile and also increased with increasing film thickness. The estimated strain-induced magnetic anisotropy field, found from XRD data, was out of plane; its value increased with film thickness and ranged from 0.47 kOe to 3.96 kOe. Ferromagnetic resonance (FMR) measurements at 5 to 21 GHz also revealed the presence of a perpendicular magnetic anisotropy that decreased with increasing film thickness and its values were smaller than values obtained from XRD data. The PLD YIG films on YAG substrates exhibiting a perpendicular anisotropy field have the potential for use in self-biased sensors and high-frequency devices.more » « less
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Abstract A multistep deposition technique is developed to produce highly oriented diamond films by hot filament chemical vapor deposition (HFCVD) on Si (111) substrates. The orientation is produced by use of a thin, 5–20 nm, Ni interlayer. Annealing studies demonstrate diffusion of Ni into Si to form nickel silicides with crystal structure depending on temperature. The HFCVD diamond film with Ni interlayer results in reduced non-diamond carbon, low surface roughness, high diamond crystal quality, and increased texturing relative to growth on bare silicon wafers. X-ray diffraction results show that the diamond film grown with 10 nm Ni interlayer yielded 92.5% of the diamond grains oriented along the (110) crystal planes with ~ 2.5 µm thickness and large average grain size ~ 1.45 µm based on scanning electron microscopy. Texture is also observed to develop for ~ 300 nm thick diamond films with ~ 89.0% of the grains oriented along the (110) crystal plane direction. These results are significantly better than diamond grown on Si (111) without Ni layer with the same HFCVD conditions. The oriented growth of diamond film on Ni interlayers is explained by a proposed model wherein the nano-diamond seeds becoming oriented relative to the β1-Ni3Si that forms during the diamond nucleation period. The model also explains the silicidation and diamond growth processes.
Article Highlights High quality diamond film with minimum surface roughness and ~93% oriented grains along (110) crystallographic direction is grown on Si substrate using a thin 5 to 20 nm nickel layer.
A detailed report on the formation of different phases of nickel silicide, its stability with different temperature, and its role for diamond film texturing at HFCVD growth condition is presented.
A diamond growth model on Si substrate with Ni interlayer to grow high quality-oriented diamond film is established.
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In this paper, high-performance UV photodetectors have been demonstrated based on indium oxide (In2O3) thin films of approximately 1.5–2 μm thick, synthesized by a simple and quick plasma sputtering deposition approach. After the deposition, the thin-film surface was treated with 4–5 nm-sized platinum (Pt) nanoparticles. Then, titanium metal electrodes were deposited onto the sample surface to form a metal–semiconductor–metal (MSM) photodetector of 50 mm2 in size. Raman scattering spectroscopy and scanning electron microscope (SEM) were used to study the crystal structure of the synthesized In2O3 film. The nanoplasmonic enhanced In2O3-based UV photodetectors were characterized by various UV wavelengths at different radiation intensities and temperatures. A high responsivity of up to 18 A/W was obtained at 300 nm wavelength when operating at 180 °C. In addition, the fabricated prototypes show a thermally stable baseline and excellent repeatability to a wide range of UV lights with low illumination intensity when operating at such a high temperature.
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1557/s43578-021-00473-2
