Controlled oxygen incorporation in indium gallium arsenide and indium phosphide grown by metalorganic vapor phase epitaxy

The defect engineering in metalorganic vapor phase epitaxy In_xGa_1-xAs and InP by controlled oxygen doping using diethyl aluminum ethoxide (DEALO) was developed in this study. DEALO doping has led to the incorporation of Al and O, and the compensation of shallow Si donors in In_xGa_1−xAs: Si with 0 ≤ x ≤ 0.25. With the same DEALO mole fraction during growth, the incorporation of Al and O was found to be independent of x, but the compensation of Si donors decreases with increasing In content. Deep level transient spectroscopy analysis on a series of In_xGa_1-xAs: Si. samples with 0 ≤ x ≤ 0.18 revealed that oxygen incorporation led to a set of deep levels, similar to those found in DEALO doped GaAs. As the In composition was increased, one or more of these deep levels became resonant with the conduction band and led to a high electron concentration in oxygen doped In_0.53Ga_0.47As. Low temperature photoluminescence emission measurements at 12K on the same set of samples revealed the quenching of the near-band edge peak, and the appearance of new oxygen-induced emission features. DEALO doping in InP has also led to the incorporation of Al and O, and the compensation of Si donors due to oxygen-induced multiple deep levels.     

Adolescents in stepfamilies: Developmental family interventions.

Discusses issues and interventions for working with adolescents who live in stepfamilies. A developmental perspective, using psychoeducation and brief strategic intervention approaches, is proposed for working with stepfamilies. Six major issues for adolescents in stepfamilies are discussed: developmental issues, sexuality issues, parent–child relationships, parenting in stepfamilies, nonresidential parent–child issues, and changes in visitation and custody. Case illustrations and suggested interventions are presented for each of these areas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individuation, peers, and adolescent alcohol use: A latent growth analysis.

The study used latent growth modeling to investigate longitudinal relationships between individuation, peer alcohol use, and adolescent alcohol use among African American, Mexican American, and non-Hispanic White adolescents (N=6,048) from 7th, 8th, and 9th grades over a 3-year period. Initial levels of peer alcohol use were significantly related to changes in adolescents' alcohol use, whereas initial adolescent alcohol use also significantly related to changes in peers' alcohol use, suggesting a bidirectional relationship. Higher levels of intergenerational individuation were related to smaller increases in adolescent alcohol use and higher levels of separation were related to larger increases in youth drinking. The findings were similar across ethnic groups. Implications for development of prevention and intervention programs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cold gas dynamic manufacturing: A non-thermal approach to freeform fabrication

This paper reports on the development of a novel freeform fabrication technique using a cold spray (CS) system. In the CS process, metallic powder particles are accelerated in a supersonic gas jet and impacted with a substrate at speeds in excess of 600 m/s. The non-melting nature of its deposition mechanism ensures that the sprayed material is free from thermally induced tensile stresses, while the underlying substrate remains unchanged. The process is seen as a viable method for additive manufacturing because of its high deposition rates and controllable spray jet. A process was developed to investigate the potential of non-thermal freeform fabrication and was coined Cold Gas Dynamic Manufacturing (CGDM). Here, additive and subtractive techniques were combined to enable the production of complex geometries. Whereas most CS facilities concentrate on the application of wear or corrosion-resistant coatings, CGDM is dedicated to the production of freeform components, whilst still retaining an inherent coating ability. The process can produce functional forms using novel manufacturing strategies that are unique to CS. This paper presents information on the process, and details the various strategies employed during component fabrication. It was possible to construct components from many materials, including titanium, which exhibited freeform surfaces, internal channels and embedded devices. A breakdown of the process economics is also provided, with and without helium recycling.