The effect of surface orientation on silicon oxidation kinetics

It is well established that the rate of thermal oxidation of silicon depends on the surface orientation, but a comprehensive model for the role of the surface orientation in the kinetic mechanism is lacking. The results of several experiments designed to develop a better understanding of which surface properties are most important in establishing the oxidation rate are reported. The results indicate that the Si surface atom density is important in the initial stages of oxidation and a revised explanation for the crossover effect is proposed

A Measurement of the Effect of Intrinsic Film Stress on the Overall Rate of Thermal Oxidation of Silicon

The effects of intrinsic film stress on Si oxidation kinetics has been receiving considerable attention in recent years. Oxidation models have appeared that relate the Si-SiO 2 interfacial intrinsic stress to both the interface reaction between oxidant and Si and to a stress altered oxidant transport. The experimental measurement of the film stress itself has been reported, although to date the data is rather sparse. Recently, in our laboratory more extensive intrinsic stress measurements have been made and these measurements will be reported separately. So while the existence of a compressive intrinsic SiO2 film stress has been experimentally verified, the experimental verification of the effects of the stress on oxidation kinetics remains a matter of speculation within the various models

An In-Situ Ellipsometric Study of Aqueous NH(4)OH Treatment of Silicon

In-situ ellipsometry is used to analyze silicon surfaces in an aqueous NH4 OH ambient. The ellipsometric data indicate that a surface which is optically quite similar to bare Si is obtained when the native SiO2 film is etched from a Si substrate by aqueous NH4OH. In contrast, the surface obtained by etching the native oxide in aqueous buffered HF leads to formation of a residual film on the Si substrate. Roughening of sample surfaces treated with either aqueous NH.OH or BHF is observed by microscopy. The high degree of roughness obtained following NH4OH treatment appears to influence ellipsometric measurements on samples, but this influence is not observed following BHF exposure where less roughness is noted

A Spectroscopic Differential Reflectometry Study of (100), (110), (111), (311), and (511) Silicon Surfaces

Spectroscopic Differential Reflectometry, SDR, has been applied to study differences in silicon surfaces with different crystallographic orientations and with very thin films. The SDR technique measures the normalized difference in reflectance of two adjacent samples in the spectral range of 250-800 nm at near normal incidence. This study demonstrates the surface sensitivity of the SDR technique to the Si crystal orientations, and to the presence of thin oxide films on the Si substrate. The observed orientation dependent spectral features are interpreted in terms of the current understanding of the silicon orientation dependent oxidation kinetics

A numerical study of bioinspired nacre-like composite plates under blast loading

In this paper, a multi-layered composite inspired by the hierarchical structure of nacre and made of layers of aluminium alloy AA 7075 bonded with toughened epoxy resin is introduced for blast resistant applications. The performance of the proposed nacre-like 3.3-mm and 5.4-mm thick composite plates, made of 1.1-mm thick AA 7075 layers, under localised impulsive loading was numerically studied. The epoxy material was modelled using user-defined interface cohesive elements that properly take into account both strength and toughness enhancements under compression. As compared to bulk plates, the improvement in blast resistance performance was numerically observed in the nacre-like plates, which required larger loads to reach the onset of failure. In addition, a reduction of the peak velocity and maximum deflection of the back face was observed for the nacre-like plates. This improvement is explained by the hierarchical structure facilitating a globalized energy absorption by inter-layer interlocking, delamination and friction.Australian Research Council through Centre of Excellence for Design in Light Metals (CE0561574). Discovery Projects (DP140100945 and DP1093485). The National Natural Science Foundation of China (No. 11232003)

Development of a self-scan to evaluate and improve person-centered care in nursing homes:A Delphi study

Background and objective: Person centered care (PCC) has become the gold standard for providing care in nursing homes (NHs). Therefore, it is important for healthcare professionals in NHs to learn PCC-skills and to be supported to learn about- and improve the quality of PCC they provide. At this moment an instrument to support healthcare professionals in NHs to monitor and evaluate PCC is limited. The aim of the study was to develop a self-evaluation tool that provides healthcare professionals in NHs insight into the extent to which they provide PCC to residents, so that they can learn and further improve their current ways of working in a person-centered way. Methods: A three-round Delphi study with an expert panel (n = 25) in the domains of PCC, quality of NH care and education of caring staff. Findings were validated by residents and relatives during semi-structured interviews. Thematic analysis and descriptive statistics were used to analyze the data. Results: In the first round the experts did not provide measuring instruments, but we identified 18 key aspects of PCC. In the second round, three clusters were identified, and a scale was added, to enable assessment. In the third round, we deduplicated, restructured and used more clear language. This led to 14 key aspects of PCC, 24 measures, grouped into five clusters: knowing the resident, establishing relationship, a respectful approach, making decisions jointly and personal development. The result is a PCC self-scan for healthcare professionals in NHs. Residents and relatives, agreed with all aspects and stated that no aspects were missing. Conclusions: In this study we developed an accessible self-report learning tool for healthcare professionals that makes it possible to evaluate and improve their PCC-skills and improve the quality of PCC in NHs

An Oxygen Tracer Study of InP Oxidation

The thermal oxidation process for InP results in a complex and process dependent oxide. From the observed self-limiting behavior of the oxide growth, the rate limiting step is likely the diffusion of reaction species through the growing oxide film. O18 marker oxidation experiments with the resulting secondary ion mass spectroscopy (SIMS) depth profiles reveal that the oxidation takes place at the oxide surface by the outward migration of In and P, rather than at the oxide-substrate interface. Based on the available results possible models for the oxidation are proposed

Ex Situ and In Situ Ellipsometric Studies of the Thermal Oxide on InP

The thermally grown InP oxide as etched by an aqueous dilute HF solution has been studied by ellipsometric techniques. The ex-situ measurement reveals a two-layer structure for the oxide grown at 440°C. The refractive indices for both oxide layers have been determined using a two-layer optical model. The etching process has also been monitored ellipsometrically in the real etching environment, in-situ. A fused silica cell, which enables the windows to be aligned properly, has been specifically designed for the in-situ solution measurement. A liquid layer at the solutionoxide interface has been identified, and the layer is shown to contain P and In species resulting from the etching reactions. A theory based on the Lorentz-Lorenz relation results in a reasonable qualitative description of the liquid layer. During the etching of the oxide the liquid layer shrinks at a linear rate, and after removal of the outer oxide layer the liquid layer forms a dense electric double layer

How do practically trained (student) caregivers in nursing homes learn?:A scoping review

Background and objective: Practically trained (student) caregivers (further: caregivers) make up the majority of care staff in nursing homes (NHs). To keep up with the fast-changing healthcare environment and ensure a high quality of care, it is important to know how to stimulate continuous work-based learning (WBL) among this group. The purpose of the study was to systematically study the scientific literature published to date on (1) how caregivers learn in NHs and (2) what facilitates or impedes their learning. Methods: A scoping review was carried out, systematically searching six scientific databases. A total of 35 studies published from January 2009 to February 2021 were included. Study characteristics, learning mechanisms, facilitators, and barriers to learning were extracted and synthesized. Results: None of the studies specifically focused on how caregivers learn. Yet, we identified various learning mechanisms, and found that learning by theory or supervision was most frequently engaged in. Most learning mechanisms used among the groups in the included studies were planned and formal and developed and initiated by others out of the context. Three main themes were identified among the facilitators and barriers of WBL: individual learning, collective learning, and resources for learning. An interdependency between (sub)themes was found. Conclusions: The way caregivers in NHs learn is understudied. Moreover, both their informal learning and the support they receive to be(come) active learners has been overlooked. As WBL provides caregivers with opportunities to learn within a real-life setting, we suggest more research on informal learning mechanisms

Electroluminescence in silicon oxynitride films

Electroluminescence (EL) was reported from 50 nm silicon oxynitride films on p-type crystalline silicon substrates in a Au/silicon oxynitride/Si structure. The EL intensity is consisted with radiative recombination of injected carriers, and has a peak below 2.45 eV. The EL can only be seen in annealed samples with the emission similar to the photoluminescence from the same samples