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crystal substrates when epitaxial growth is pursued. These requirements dramatically limit their applicability excluding the possibility to prepare many artificial multilayered architectures to investigate emergent phenomena that arise in thin films and at their interfaces, [2] as well as the fabrication of flexible devices and monolithic integration into silicon. [3-5] Many efforts have been devoted to develop procedures to detach the functional oxide film from the growth substrate in order to be able to freely manipulate it. They include mechanical exfoliation, [6] dry etching, [7,8] and wet-chemical etching. [9,10] Among the chemical etching procedures, the use of a sacrificial layer, which is incorporated between the substrate and the functional oxide, appears as a fast and relatively low-cost process. For this approach to be successful, the sacrificial layer should transfer the epitaxy from the substrate to the desired oxide, stand the deposition process of the functional oxide and be selectively removed by a chemical treatment, which allows to retrieve the original single-crystal substrate. (La,Sr)MnO 3 has been proved effective to be selectively etched by an acid blend allowing the transfer of single epitaxial Pb(Zr,Ti)O 3 layers [11] and more complex architectures such as SrRuO 3 /Pb(Zr,Ti)O 3 /SrRuO 3. [12] Recently, the use of water-soluble Sr 3 Al 2 O 6 (SAO) sacrificial layer enlarged the family of free-standing epitaxial perovskite oxide layers (SrTiO 3 , BiFeO 3 , BaTiO 3) [13-15] and multilayers (SrTiO 3 /(La,Sr) MnO 3) [16] that can be manipulated opening a whole new world of opportunities. [5,10,17] The deposition techniques to prepare such structures is also a key factor to be considered not only for film quality but also for process scalability. While high vacuum deposition techniques such as molecular beam epitaxy and pulsed laser deposition are well established techniques to produce high quality films, [1,18-20] alternate procedures that can deliver low-cost production such as solution processing and atomic layer deposition are gaining interest. [21,22] Chemical solution deposition (CSD) is considered a mature technique for the preparation of oxide films. The synthesis of ternary and quaternary oxides is not a trivial task but the pioneering work done in ferroelectric lead zirconate titanate inspired many researchers to extend it to other compositions and broaden the application fields. [23,24] Nonetheless, there is still a myriad of compositions to be explored, including SAO, The growth of epitaxial complex oxides has been essentially limited to specific substrates that can induce epitaxial growth and stand high temperature thermal treatments. These restrictions hinder the opportunity to manipulate and integrate such materials into new artificial heterostructures including the use of polymeric and silicon substrates and study emergent phenomena for novel applications. To tackle this bottleneck, herein, a facile chemical route to prepare water-soluble epitaxial Sr 3 Al 2 O 6 thin films to be ...

Sb 2 Se 3 is a quasi-one-dimensional (1D) semiconductor, which has shown great promise in photovoltaics. However, its performance is currently limited by a high V oc deficit. Therefore, it is necessary to explore new strategies to minimize the formation of intrinsic defects and thus unlock the absorber’s whole potential. It has been reported that tuning the Se/Sb relative content could enable a selective control of the defects. Furthermore, recent experimental evidence has shown that moderate Se excess enhances the photovoltaic performance; however, it is not yet clear whether this excess has been incorporated into the structure. In this work, a series of Sb 2 Se 3 thin films have been prepared imposing different nominal compositions (from Sb-rich to Se-rich) and then have been thoroughly characterized using compositional, structural, and optical analysis techniques. Hence, it is shown that Sb 2 Se 3 does not allow an extended range of nonstoichiometric conditions. Instead, any Sb or Se excesses are compensated in the form of secondary phases. Also, a correlation has been found between operating under Se-rich conditions and an improvement in the crystalline orientation, which is likely related to the formation of a MoSe 2 phase in the back interface. Finally, this study shows new utilities of Raman, X-ray diffraction, and photothermal deflection spectroscopy combination techniques to examine the structural properties of Sb 2 Se 3 , especially how well-oriented the material is.

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A centralized polarization scrambling and single-PD coherent ONU Rx system is proposed and tested with two Tx and direct-phase modulated DFBs. Polarization independence at the Rx, and a sensitivity at BER=10-3 of ×45dBm with 7.5GHz channel spacing were achieved.Peer ReviewedPostprint (published version

A homodyne coherent receiver for ultra-dense WDM-PON with off the shelf components is presented. It consists of a conventional DFB, phase switched clock signal, an optical coupler instead of a 90º hybrid, balanced photodetectors and digital signal processing. The phase swing for a DBPSK signal was optimized and the performance was experimentally evaluated in terms of the sensitivity for several laser linewidths. The acceptable frequency offset and clock time delay was also assessed. The results exhibit a sensitivity of-48 dBm at a BER of 10-3 and indicate a high tolerance to phase noise.

A simple and low cost method for wavelength control of economical random non-preselected independent ONU sources is shown to increase the number of users in an OFDMA-PON. The method is based on OLT monitoring and thermal tuning control; it has been validated through Monte-Carlo simulations and a probabilistic model. The minimum optical spectral gap between the ONUs wavelengths that guarantees a tolerable amount of optical beat interference has been determined through an experiment.