ORCID Profile
0000-0002-8230-6059
Current Organisations
University of Granada
,
University of Cadiz
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Publisher: American Chemical Society (ACS)
Date: 28-06-2021
Publisher: Elsevier BV
Date: 12-2016
Publisher: American Chemical Society (ACS)
Date: 09-07-2020
Publisher: AIP Publishing
Date: 07-04-2014
DOI: 10.1063/1.4870533
Abstract: The influence of growth temperature on the synthesis of BexZn1−xO alloy films, grown on highly-mismatched Al2O3(0001) substrates, was studied by synchrotron x-ray scattering, high-resolution transmission electron microscopy and photoluminescence measurements. A single-phase BexZn1−xO alloy with a Be concentration of x = 0.25, was obtained at the growth temperature, Tg = 400 °C, and verified by high-resolution transmission electron microscopy. It was found that high-temperature growth, Tg≥600 °C, caused phase separation, resulting in a random distribution of intermixed alloy phases. The inhomogeneity and structural fluctuations observed in the BexZn1−xO films grown at high temperatures are attributed to a variation in Be composition and mosaic distribution via atomic displacement and strain relaxation.
Publisher: Springer Science and Business Media LLC
Date: 16-01-2015
DOI: 10.1038/SREP07719
Abstract: Bulk crystals and thin films of PbTi 1− x Fe x O 3−δ (PTFO) are multiferroic, exhibiting ferroelectricity and ferromagnetism at room temperature. Here we report that the Ruddlesden-Popper phase Pb n +1 (Ti 1− x Fe x ) n O 3 n +1−δ forms spontaneously during pulsed laser deposition of PTFO on LaAlO 3 substrates. High-resolution transmission electron microscopy, x-ray diffraction and x-ray photoemission spectroscopy were utilised to perform a structural and compositional analysis, demonstrating that "Equation missing" and "Equation missing" . The complex dielectric function of the films was determined from far-infrared to ultraviolet energies using a combination of terahertz time-domain spectroscopy, Fourier transform spectroscopy and spectroscopic ellipsometry. The simultaneous Raman and infrared activity of phonon modes and the observation of second harmonic generation establishes a non-centrosymmetric point group for Pb n +1 (Ti 0.5 Fe 0.5 ) n O 3 n +1−δ , a prerequisite for (but not proof of) ferroelectricity. No evidence of macroscopic ferromagnetism was found in SQUID magnetometry. The ultrafast optical response exhibited coherent magnon oscillations compatible with local magnetic order and additionally was used to study photocarrier cooling on picosecond timescales. An optical gap smaller than that of BiFeO 3 and long photocarrier lifetimes may make this system interesting as a ferroelectric photovoltaic.
Publisher: American Chemical Society (ACS)
Date: 08-05-2019
Publisher: AIP Publishing
Date: 17-12-2007
DOI: 10.1063/1.2825274
Abstract: Tunable capacitors with a Cu∕PbxSr1−xTiO3∕Cu parallel-plate structure have been fabricated using a layer transfer method. The use of a Cu bottom electrode results in a giant electrode Q-factor×capacitor area product of QelecA=3.79×105μm2 at 1GHz. The dielectric constant at room temperature is 420 and the tunability amounts to 73% near a breakdown voltage of 35V. The major advantages of the layer transfer method include low electrode losses, the freedom to select an auxiliary substrate and seed layer for ferroelectric film growth irrespective of their high-frequency properties, and the possibility to utilize a large variety of device substrates as they no longer act as template for film growth.
Publisher: American Chemical Society (ACS)
Date: 23-06-2021
Publisher: American Chemical Society (ACS)
Date: 20-04-2020
Publisher: Springer Science and Business Media LLC
Date: 12-2019
Publisher: American Chemical Society (ACS)
Date: 13-02-2023
Publisher: American Chemical Society (ACS)
Date: 06-07-2015
Publisher: Springer Science and Business Media LLC
Date: 17-03-2020
DOI: 10.1038/S41377-020-0279-Y
Abstract: Continuous room temperature nanowire lasing from silicon-integrated optoelectronic elements requires careful optimisation of both the lasing cavity Q -factor and population inversion conditions. We apply time-gated optical interferometry to the lasing emission from high-quality GaAsP/GaAs quantum well nanowire laser structures, revealing high Q -factors of 1250 ± 90 corresponding to end-facet reflectivities of R = 0.73 ± 0.02. By using optimised direct–indirect band alignment in the active region, we demonstrate a well-refilling mechanism providing a quasi-four-level system leading to multi-nanosecond lasing and record low room temperature lasing thresholds (~6 μJ cm −2 pulse −1 ) for III–V nanowire lasers. Our findings demonstrate a highly promising new route towards continuously operating silicon-integrated nanolaser elements.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Ana Sanchez.