Radioactive silicon as a marker in thin-film silicide formation

A new technique using radioactive 31Si (half-life =2.62 h), formed in a nuclear reactor, as a marker for studying silicide formation is described. A few hundred angstroms of radioactive silicon is first deposited onto the silicon substrate, followed immediately by the deposition of a few thousand angstroms of the metal. When the sample is heated, a silicide is first formed with the radioactive silicon. Upon further silicide formation, this band of radioactive silicide can move to the surface of the sample if silicide formation takes place by diffusion of the metal or by silicon substitutional and/or vacancy diffusion. However, if the band of radioactive silicide stays at the silicon substrate interface it can be concluded that silicon diffuses by interstitial and/or grain-boundary diffusion. This technique was tested by studying the formation of Ni2Si on silicon at 330 °C. From a combination of ion-beam sputtering, radioactivity measurement, and Rutherford backscattering it is found that the band of radioactive silicide moves to the surface of the sample during silicide formation. From these results, implanted noble-gas marker studies and the rate dependence of Ni2Si growth on grain size, it is concluded that nickel is the dominant diffusing species during Ni2Si formation, and that it moves by grain-boundary diffusion

Algebraic Rainich conditions for the tensor V

Algebraic conditions on the Ricci tensor in the Rainich-Misner-Wheeler unified field theory are known as the Rainich conditions. Penrose and more recently Bergqvist and Lankinen made an analogy from the Ricci tensor to the Bel-Robinson tensor $B_{\alpha\beta\mu\nu}$, a certain fourth rank tensor quadratic in the Weyl curvature, which also satisfies algebraic Rainich-like conditions. However, we found that not only does the tensor $B_{\alpha\beta\mu\nu}$ fulfill these conditions, but so also does our recently proposed tensor $V_{\alpha\beta\mu\nu}$, which has many of the desirable properties of $B_{\alpha\beta\mu\nu}$. For the quasilocal small sphere limit restriction, we found that there are only two fourth rank tensors $B_{\alpha\beta\mu\nu}$ and $V_{\alpha\beta\mu\nu}$ which form a basis for good energy expressions. Both of them have the completely trace free and causal properties, these two form necessary and sufficient conditions. Surprisingly either completely traceless or causal is enough to fulfill the algebraic Rainich conditions. Furthermore, relaxing the quasilocal restriction and considering the general fourth rank tensor, we found two remarkable results: (i) without any symmetry requirement, the algebraic Rainich conditions only require totally trace free; (ii) with a symmetry requirement, we recovered the same result as in the quasilocal small sphere limit.Comment: 17 page

Dissociation mechanism for solid-phase epitaxy of silicon in the Si <100>/Pd2Si/Si (amorphous) system

Solid-phase epitaxial growth (SPEG) of silicon was investigated by a tracer technique using radioactive 31Si formed by neutron activation in a nuclear reactor. After depositing Pd and Si onto activated single-crystal silicon substrates, Pd2Si was formed with about equal amounts of radioactive and nonradioactive Si during heating at 400 °C for 5 min. After an 1-sec annealing stage (450-->500 °C in 1 h) this silicide layer, which moves to the top of the sample during SPEG, is etched off with aqua regia. From the absence of radioactive 31Si in the etch, it is concluded that SPEG takes place by a dissociation mechanism rather than by diffusion

Structural difference rule for amorphous alloy formation by ion mixing

We formulate a rule which establishes a sufficient condition that an amorphous binary alloy will be formed by ion mixing of multilayered samples when the two constituent metals are of different crystalline structure, regardless of their atomic sizes and electronegativities. The rule is supported by the experimental results we have obtained on six selected binary metal systems, as well as by the previous data reported in the literature. The amorphization mechanism is discussed in terms of the competition between two different structures resulting in frustration of the crystallization process

Heterostructure by solid‐phase epitaxy in the Si〈111〉/Pd/Si (amorphous) system

When a thin film of Pd reacts with a 〈111〉 Si substrate, a layer of epitaxial Pd_2Si is formed. It is shown that Si can grow epitaxially on such a layer by solid‐phase reaction

Big Five Personality Traits, Pathological Personality Traits, and Psychological Dysregulation: Predicting Aggression and Antisocial Behaviors in Detained Adolescents

This study tested the utility of three different models of personality, namely the social and personality model, the pathological personality traits model, and the psychological dysregulation model, in predicting overt aggression, relational aggression, and delinquency in a sample of detained boys (ages 12 to 18; M age = 15.31; SD = 1.16). Results indicated that the three personality approaches demonstrated different unique associations with aggression and delinquency. The psychological dysregulation approach, composed of behavioral dysregulation, emotional dysregulation, and cognitive dysregulation, emerged as the overall best predictor of overt aggression, relational aggression, and delinquency. After controlling for the Big Five personality traits, psychological dysregulation accounted for significant variance in overt aggression and delinquency, but not relational aggression. After controlling for callous-unemotional traits and narcissistic traits, psychological dysregulation also accounted for significant variance in overt aggression, relational aggression, and delinquency. Psychological dysregulation did not account for significant variance in aggression or delinquency after controlling for borderline traits. The pathological personality traits approach, comprised of callous-unemotional traits, narcissistic traits, and borderline traits performed second best. In particular, within this approach borderline traits accounted for the most unique variance, followed by narcissistic traits, then callous-unemotional traits. Borderline traits accounted for significant variance in overt aggression, relational aggression, and delinquency when controlling for the Big Five traits, but not after controlling for psychological dysregulation. Narcissistic traits only accounted for significant variance in overt aggression and relational aggression after controlling for the Big Five personality traits, but not after controlling for psychological dysregulation. CU traits only accounted for significant variance in overt aggression after controlling for the Big Five personality traits, but not after controlling for psychological dysregulation. The social and personality model, represented by the Big Five personality traits accounted for the least amount of variance in the prediction of aggression and delinquency, on its own, and when pitted against the other two personality approaches. The exception was that the Big Five personality traits accounted for significant variance in relational aggression beyond narcissistic traits, as well as psychological dysregulation. These findings have implications for assessment and intervention with aggressive and antisocial youth

Big Five Personality Traits, Pathological Personality Traits, and Psychological Dysregulation: Predicting Aggression and Antisocial Behaviors in Detained Adolescents

This study tested the utility of three different models of personality, namely the social and personality model, the pathological personality traits model, and the psychological dysregulation model, in predicting overt aggression, relational aggression, and delinquency in a sample of detained boys (ages 12 to 18; M age = 15.31; SD = 1.16). Results indicated that the three personality approaches demonstrated different unique associations with aggression and delinquency. The psychological dysregulation approach, composed of behavioral dysregulation, emotional dysregulation, and cognitive dysregulation, emerged as the overall best predictor of overt aggression, relational aggression, and delinquency. After controlling for the Big Five personality traits, psychological dysregulation accounted for significant variance in overt aggression and delinquency, but not relational aggression. After controlling for callous-unemotional traits and narcissistic traits, psychological dysregulation also accounted for significant variance in overt aggression, relational aggression, and delinquency. Psychological dysregulation did not account for significant variance in aggression or delinquency after controlling for borderline traits. The pathological personality traits approach, comprised of callous-unemotional traits, narcissistic traits, and borderline traits performed second best. In particular, within this approach borderline traits accounted for the most unique variance, followed by narcissistic traits, then callous-unemotional traits. Borderline traits accounted for significant variance in overt aggression, relational aggression, and delinquency when controlling for the Big Five traits, but not after controlling for psychological dysregulation. Narcissistic traits only accounted for significant variance in overt aggression and relational aggression after controlling for the Big Five personality traits, but not after controlling for psychological dysregulation. CU traits only accounted for significant variance in overt aggression after controlling for the Big Five personality traits, but not after controlling for psychological dysregulation. The social and personality model, represented by the Big Five personality traits accounted for the least amount of variance in the prediction of aggression and delinquency, on its own, and when pitted against the other two personality approaches. The exception was that the Big Five personality traits accounted for significant variance in relational aggression beyond narcissistic traits, as well as psychological dysregulation. These findings have implications for assessment and intervention with aggressive and antisocial youth

Quantum walk of two anyons across a statistical boundary

We model a quantum walk of identical particles that can alter their exchange statistics by hopping across a domain wall in a one-dimensional lattice. Such a "statistical boundary" is transparent to single particles and affects the dynamics only by swapping multiple particles arriving together. We find that the two-particle interference is dramatically altered by reflections of these bunched waves at the interface, producing strong measurable asymmetries. Depending on the phases on the two sides, a bunched wave packet can get completely reflected or split into a superposition of a reflected wave and an antibunched wave. This leads to striking dynamics with two domain walls, where bunched waves can get trapped in between or fragment into multiple correlated single-particle wave packets. These findings can be realized with density-dependent hopping in present-day atomic setups and open up a paradigm of intrinsically many-body phenomena at statistical boundaries

Exploring Narcissism, Psychopathy, and Machiavellianism in Youth: An Examination of Associations with Antisocial Behavior and Aggression

This study sought to explore the differential associations of CU traits, narcissistic traits, and Machiavellian traits with overt aggression, relational aggression, delinquency, behavioral dysregulation, and emotional dysregulation in a community sample of boys and girls (ages 11-17). Results indicated that the three personality traits were significantly correlated with each other, yet distinct. CU traits, narcissistic traits, and Machiavellian traits demonstrated different unique associations with behavior problems. Specifically, narcissistic traits showed the strongest unique associations with overt aggression, relational aggression, behavioral dysregulation, and emotional dysregulation. CU traits showed the second strongest unique associations with overt aggression, delinquency and behavioral dysregulation, but were not associated with relational aggression or emotional dysregulation. Lastly, Machiavellian traits showed a strong unique association with emotional dysregulation, but were not uniquely associated with externalizing behavior problems. These findings have implications for intervention with aggressive and antisocial youth