Oxygen Concentration Effect on Conductive Bridge Random Access Memory of InWZnO Thin Film

In this study, the influence of oxygen concentration in InWZnO (IWZO), which was used as the switching layer of conductive bridge random access memory, (CBRAM) is investigated. With different oxygen flow during the sputtering process, the IWZO film can be fabricated with different oxygen concentrations and different oxygen vacancy distribution. In addition, the electrical characteristics of CBRAM device with different oxygen concentration are compared and further analyzed with an atomic force microscope and X-ray photoelectron spectrum. Furthermore, a stacking structure with different bilayer switching is also systematically discussed. Compared with an interchange stacking layer and other single layer memory, the CBRAM with specific stacking sequence of bilayer oxygen-poor/-rich IWZO (IWZOx/IWZOy, x < y) exhibits more stable distribution of a resistance state and also better endurance (more than 3 × 104 cycles). Meanwhile, the memory window of IWZOx/IWZOy can even be maintained over 104 s at 85 °C. Those improvements can be attributed to the oxygen vacancy distribution in switching layers, which may create a suitable environment for the conductive filament formation or rupture. Therefore, it is believed that the specific stacking bilayer IWZO CBRAM might further pave the way for emerging memory applications.

Tuneable local order in thermoelectric crystals

Although crystalline solids are characterized by their periodic structures, some are only periodic on average and deviate on a local scale. Such disordered crystals with distinct local structures have unique properties arising from both collective and localized behaviour. Different local orderings can exist with identical average structures, making their differences hidden to Bragg diffraction methods. Using high-quality single-crystal X-ray diffuse scattering the local order in thermoelectric half-Heusler Nb1−x CoSb is investigated, for which different local orderings are observed. It is shown that the vacancy distribution follows a vacancy repulsion model and the crystal composition is found always to be close to x = 1/6 irrespective of nominal sample composition. However, the specific synthesis method controls the local order and thereby the thermoelectric properties thus providing a new frontier for tuning material properties.

Oxygen Vacancy Distribution and Electron Localization on Nanocube CeO2(100)

In this work, the oxygen vacancies distribution in the 5nm CeO2 nanocubes was determined by Reverse Monte Carlo (RMC) simulations for the neutron total scattering atomic pair distribution function (PDF)...

Education in the Mais Médicos program: the gap between proposals and implementation

Introduction: The scarcity and inequalities in the geographical distribution of physicians challenge the consolidation of the right to health and create migratory flows that increase health inequities. Due to their complex and multidimensional characteristics, they demand multisectoral political approaches, considering several factors related to the availability and area of practice of medical doctors, as well as the social vulnerability of local populations. Objective: This study aimed at analysing results of the “Mais Médicos” (More Doctors) Program Educational Axis in Brazil. Methodology: A documental research was conducted, highlighting the location and the public or private nature of new undergraduate medical school vacancies between the years 2013 until 2017, which were then compared to the goals and strategies outlined in the official Program documents. Results: The Educational Axis reached important milestones despite the resistance of some institutional actors. The Program extended its undergraduate vacancies by 7696 places, 22.48% of that in public institutions and 77.52% in private ones. Vacancy distribution prioritized cities in rural areas of Brazil, at the same instance bringing forward significant regulatory changes for undergraduate medical courses. However, political disputes with representatives of medical societies and stakeholders interested in favouring the private educational and healthcare sectors surface in the official discourses and documents. These factors weakened the program normative body, creating a hiatus between its core objectives and respective implementation. Evidence related to the concentration of vacancies in the Southeast regions allow the maintenance of a known unequal workforce distribution, despite a proportionally bigger increase in the Midwest, North and Northeast regions. Conclusion: The predominance of vacancies in private institutions and the weakening of the new undergraduate courses monitoring instruments can compromise changes in the graduate students’ profiles, which are necessary for the fixation of physicians in strategic geographic areas to promote Primary Healthcare.

A dimensão da formação no Programa Mais Médicos: hiato entre propostas e implementação

Introduction: The scarcity and inequalities in the geographical distribution of physicians challenge the consolidation of the right to health and create migratory flows that increase health inequities. Due to their complex and multidimensional characteristics, they demand multisectoral political approaches, considering several factors related to the availability and area of practice of medical doctors, as well as the social vulnerability of local populations. Objective: This study aimed at analysing results of the “Mais Médicos” (More Doctors) Program Educational Axis in Brazil. Methodology: A documental research was conducted, highlighting the location and the public or private nature of new undergraduate medical school vacancies between the years 2013 until 2017, which were then compared to the goals and strategies outlined in the official Program documents. Results: The Educational Axis reached important milestones despite the resistance of some institutional actors. The Program extended its undergraduate vacancies by 7696 places, 22.48% of that in public institutions and 77.52% in private ones. Vacancy distribution prioritized cities in rural areas of Brazil, at the same instance bringing forward significant regulatory changes for undergraduate medical courses. However, political disputes with representatives of medical societies and stakeholders interested in favouring the private educational and healthcare sectors surface in the official discourses and documents. These factors weakened the program normative body, creating a hiatus between its core objectives and respective implementation. Evidence related to the concentration of vacancies in the Southeast regions allow the maintenance of a known unequal workforce distribution, despite a proportionally bigger increase in the Midwest, North and Northeast regions. Conclusion: The predominance of vacancies in private institutions and the weakening of the new undergraduate courses monitoring instruments can compromise changes in the graduate students’ profiles, which are necessary for the fixation of physicians in strategic geographic areas to promote Primary Healthcare.

Numerical Analysis of Oxygen Vacancy Distribution in Semiconductor Gas Sensors in the Cooling Process Based on the Model of Gradient-Distributed Oxygen Vacancies

The oxygen vacancies (VO) play an essential role in the gas-sensing mechanism of semiconductor devices. A diffusion equation is established to describe the VO behaviors during a cooling process based on the model of gradient-distributed oxygen vacancies. Numerical solutions of the diffusion equation are found to illustrate the VO distribution in grains. The gradient of VO distribution is of negative dependence on the cooling rate, which also influences the average VO density in the depletion layer. The migration of oxygen vacancies in cooling process could be interrupted by quenching and it is restarted by the re-annealing process. The VO distributing process is illustrated by three stages from initial uniform distribution to final gradient profile via a transient stage. The influence of VO distribution on gas-sensing characteristics of semiconductor grains is discussed. Potential opportunities are found to control the gas sensor characteristics by a designed annealing process.