Single crystalline SnO2 thin films grown on m-plane sapphire substrate by mist chemical vapor deposition

Tin dioxide (SnO2) thin films, as a candidate for realizing next‐generation electrical and optical devices, were grown on 2‐inch diameter m ‐plane sapphire substrates by mist chemical vapour deposition at atmospheric pressure. The SnO2 thin films were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), X‐ray diffraction (XRD) in θ–2θ and φ scanning modes, and electron backscatter diffraction (EBSD). Although the SEM and AFM images showed a relatively rough surface morphology, it was found from the XRD and EBSD measurements that SnO2 films were epitaxially grown on the substrates under optimised growth condition. Epitaxial growth of SnO2 thin film growth at three typical areas on the substrate was confirmed by the EBSD measurements. It is likely that the single crystalline SnO2 (001) thin film was formed across the 2‐inch sapphire substrate. Finally, the second SnO2 layer was overgrown on the above single crystalline SnO2 thin film, which functioned as a buffer layer. This method which drastically improved surface roughness of the second SnO2 layer

Single crystalline SnO2 thin films grown on m-plane sapphire substrate by mist chemical vapor deposition

Tin dioxide (SnO2) thin films, as a candidate for realizing next‐generation electrical and optical devices, were grown on 2‐inch diameter m ‐plane sapphire substrates by mist chemical vapour deposition at atmospheric pressure. The SnO2 thin films were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), X‐ray diffraction (XRD) in θ–2θ and φ scanning modes, and electron backscatter diffraction (EBSD). Although the SEM and AFM images showed a relatively rough surface morphology, it was found from the XRD and EBSD measurements that SnO2 films were epitaxially grown on the substrates under optimised growth condition. Epitaxial growth of SnO2 thin film growth at three typical areas on the substrate was confirmed by the EBSD measurements. It is likely that the single crystalline SnO2 (001) thin film was formed across the 2‐inch sapphire substrate. Finally, the second SnO2 layer was overgrown on the above single crystalline SnO2 thin film, which functioned as a buffer layer. This method which drastically improved surface roughness of the second SnO2 layer

Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo

International audienceIntermediate-mass black holes (IMBHs) span the approximate mass range 100−105 M⊙, between black holes (BHs) that formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass ∼150 M⊙ providing direct evidence of IMBH formation. Here, we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modeled (matched filter) and model-independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200 M⊙ and effective aligned spin 0.8 at 0.056 Gpc−3 yr−1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpc−3 yr−1.Key words: gravitational waves / stars: black holes / black hole physicsCorresponding author: W. Del Pozzo, e-mail: [email protected]† Deceased, August 2020