Innovative patterning method for modifying few-layer MoS2 device geometries

When mechanically exfoliated two-dimensional (2D) materials are used for device applications, their properties strongly depend on the geometry and number of layers present in the flake. In general, these properties cannot be modified once a device has been fabricated out of an exfoliated flake. In this work we present a novel nano-patterning method for 2D material based devices, Pulsed eBeam Gas Assisted Patterning (PEBGAP), that allows us to fine tune their geometry once the device fabrication steps have been completed

A fast synthesis route of boron-carbon-nitrogen ultrathin layers towards highly mixed ternary B-C-N phases

We report a direct and fast synthesis route to grow boron-carbon-nitrogen layers based on microwave-assisted plasma enhanced chemical vapour deposition (PECVD) by using methylamine borane as a single source molecular precursor. This easy and inexpensive method allows controlled and reproducible growth of B-C-N layers onto thin Cu foils. Their morphological, structural, chemical, optical and transport properties have been thoroughly characterized by a number of different microscopies, transport and spectroscopic techniques. Though disorder and segregation into C-rich and h-BN-rich domains have been observed in ultrathin flat few layers, high doping levels have been reached, inducing strong modifications of the electronic, optical and transport properties of C-rich and h-BN-rich phases. This synthesis procedure can open new routes towards the achievement of homogeneous highly mixed ternary B-C-N phase

A genetic modifier screen identifies chromosomal intervals harboring potential midline interacting genes

This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and Graphene-like (Gr) domains. However, there is an important presence of B and N interactions with C at the Gr borders, and of C interacting at the h-BN-edges, respectively, in the obtained nano-layers. In particular, there is significant presence of C-N bonds, at Gr/h-BN borders and in the form of N doping of Gr domains. The overall B:C:N contents in the layers is close to 1:3:1.5. A careful analysis of the optical bandgap determination of the obtained B-C-N layers is presented, discussed and compared with previous seminal works with samples of similar composition.Comment: 35 pages, 7 figure

Chemical vapor deposition growth of boron-carbon-nitrogen layers from methylamine borane thermolysis products

This is the Accepted Manuscript version of an article accepted for publication in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6528/aa9c07This work investigates the growth of B-C-N layers by chemical vapor deposition using methylamine borane (MeAB) as the single-source precursor. MeAB has been synthesized and characterized, paying particular attention to the analysis of its thermolysis products, which are the gaseous precursors for B-C-N growth. Samples have been grown on Cu foils and transferred onto different substrates for their morphological, structural, chemical, electronic and optical characterizations. The results of these characterizations indicate a segregation of h-BN and graphene-like (Gr) domains. However, there is an important presence of B and N interactions with C at the Gr borders, and of C interacting at the h-BN-edges, respectively, in the obtained nano-layers. In particular, there is a significant presence of C-N bonds, at Gr/h-BN borders and in the form of N doping of Gr domains. The overall B:C:N contents in the layers is close to 1:3:1.5. A careful analysis of the optical bandgap determination of the obtained B-C-N layers is presented, discussed and compared with previous seminal works with samples of similar compositio

Financial crisis and income-related inequalities in the universal provision of a public service: the case of healthcare in Spain

Background The objective of this paper is to analyse whether the recent recession has altered health care utilisation patterns of different income groups in Spain. Methods Based on information concerning individuals ‘income and health care use, along with health need indicators and demographic characteristics (provided by the Spanish National Health Surveys from 2006/07 and 2011/12), econometric models are estimated in two parts (mixed logistic regressions and truncated negative binominal regressions) for each of the public health services studied (family doctor appointments, appointments with specialists, hospitalisations, emergencies and prescription drug use). Results The results show that the principle of universal access to public health provision does not in fact prevent a financial crisis from affecting certain income groups more than others in their utilisation of public health services. Conclusions Specifically, in relative terms the recession has been more detrimental to low-income groups in the cases of specialist appointments and hospitalisations, whereas it has worked to their advantage in the cases of emergency services and family doctor appointments

Tailoring of the optoelectronic properties of few layer Molybdenum Disulfide (MoS2) Devices via Pulsed eBeam Gas Assisted Patterning

Two dimensional materials have received much attention in recent years for their outstanding properties. Semiconducting 2D MoS2 is considered a good candidate for device applications due to its superior electrical and optical properties. Optoelectronic properties of MoS2 flakes strongly depend on the geometry and number of atomic layers present in the flake. In general, these properties can not be modified once a device is fabricated. In this work we present prelimiary results on a novel nano-patterning method, pulsed e-beam gas assisted patterning (PEBGAP), that allows us to tailor the electronic or optical properties of MoS2 devices. We can modify the carrier channel geometry, its thickness or even underetch it to release a suspended membrane. Field effect devices were fabricated from mechanically exfoliated few-layer MoS2 flakes via optical and electron beam lithography followed by a metal evaporation and lift-off process to define the gate-contact structures. The devices were characterised employing Optical (Raman, μPL) and electrical light dependence transport measurements and Scanning Near Field Optical Microscopy (SNOM). Afterwards, PEBGAP was utilized to alter device geometries and structures with the aim of modifying their optoelectronic properties. By using this method, it may also be possible to bring out new physical phenomena in this material (superconductivity of suspended MoS2 wires in membranes, quantum correlation phenomena, magnetic response, etc.) or develope new routes towards nano-electro-mechanical-optical systems (NEMOS). We will show our preliminary results of the devices properties before and after their modification