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Porous-Silicon/Zinc Oxide (PS-ZnO) nanocomposites can be processed by a combination of electrochemical etching of PS and sol-gel infiltration of ZnO, which leads to complex interfaces of ZnO permeated in the PS matrix. In this work, an approach consisting on the determination of transport mechanisms and identification of electroluminescence emission bands from the heterojunction, has been followed to derive the energy band diagram. Charge transport at room temperature has been determined in ITO/PS-ZnO/p+-Si/Al structures through current-voltage characteristics, showing that direct and Fowler-Nordheim (FN) tunneling are the main conduction mechanisms at low and high bias voltages, respectively. White electroluminescence composed of three main bands (~490, ~550 and ~620 nm) is observed at forward bias. Emission starts at a threshold voltage of 3.9±0.2 V, in coincidence with the change in conduction mechanism from direct to FN tunneling. A band diagram of the device is derived from the emission and transport properties, which is coherent with previous electronic and microstructural properties of the starting n-ZnO and p+-Si.

A novel procedure, based in a closed space vapor transport (CSVT) configuration, has been devised to grow films or flakes of pure MoO2 in a reductive atmosphere, at relatively low temperature and using MoO3 as the source. In contrast with conventional CSVT technique, in the proposed method a temperature gradient is not required for the growth to take place, which occurs through an intermediate volatile transport species that is produced in the complex reduction reaction of MoO3. An added value of this simple method is the possibility of transforming the MoO2 into MoTe2, one of the most interesting members of the transition metal dichalcogenide family. This is achieved in a sequential process that includes the growth of Mo oxide and its (in-situ) tellurization in two consecutive steps.

This paper details the development of a lab-made experimental setup for surface photovoltage spectroscopy (SPS) measurements using an open-source and Arduino® microcontroller to control a monochromator and some off-the-shelf electronic components. The experimental setup is interfaced to a computer, where LabVIEW® based software manages system control and data acquisition. We also report the design of a compact sample holder, simple and easy to manufacture and handle. Results of the application of SPS to the characterization of MoO3 thin films and semiconductor laser structures are presented to validate the performance of the setup, highlighting the effectiveness of SPS for the characterization of semiconductor materials and devices.

The aim of the present work is the growth by PVD techniques and ulterior characterization of electrical contacts to columnar porous silicon (PSi) as an approach to reliable PSi sensor devices. Contacts consist of a NiCr (40:60) and Au bilayer on the PSi surface deposited by magnetron sputtering. These structures show a good adhesion to the rough surface of columnar PSi. The morphology of these electrical contacts is characterized by electron microscopy and their crystalline structure by X-ray diffraction. Compositional profiles are determined by Rutherford backscattering spectroscopy and energy dispersive X-ray spectroscopy, which demonstrate that the infiltration of NiCr into the PSi is at the origin of the metallic thin film adhesion improvement. I–V characteristics and impedance spectroscopy measurements show that this configuration provides rectifying electrical contacts to PSi, for which a simple equivalent circuit based on one resistor and two capacitors can be modeled. These results further support the use of PSi electrical structures for sensing purposes.