CdS thin film post-annealing and Te–S interdiffusion in a CdTe/CdS solar cell

Small area CdTe/CdS solar cells were fabricated using chemical bath deposited CdS and CSS deposited CdTe thin films to investigate the interface properties related to the CdS processing. The effect of post deposition annealing of CdS on the junction properties and the possible interdiffusion at the interface is discussed. The hypothesis of hardening of CdS due to annealing against the diffusion of “S” and “Te” is discussed using the quantum efficiency data in the blue and red regions. Devices prepared using as-deposited CdS films exhibited evidences of higher “S” and “Te” diffusion compared to devices made using CdS films annealed in oxygen. The maximum efficiency of the devices used in this study was 9.8%.     

Advances in Linear Modeling of Microwave Transistors

Heterojunction field effect transistors (HFET) based on gallium nitride (AlGaN/GaN) and metal semiconductor field effect transistors (MESFETs) based on silicon carbide (SiC) are the preferred transistors for high-power amplifier circuit designs rather than MESFETs, high electron mobility transistors (HEMTs) and pseudomorphic HEMTs based on gallium arsenide (GaAs) or indium phosphide (InP) semiconductor technology. While AlGaN/GaN and SiC are good candidates for high-power applications, GaAs and InP semiconductor technologies are the preferred transistors in low-power, low-voltage, and low-noise applications [1].     

Solving timetabling problems using a cultural algorithm

This paper addresses the solution of timetabling problems using cultural algorithms. The core idea is to extract problem domain information during the evolutionary search, and then combine it with some previously proposed operators, in order to improve performance. The proposed approach is validated using a benchmark of 20 instances, and its results are compared with respect to three other approaches: two evolutionary algorithms and simulated annealing, all of which have been previously adopted to solve timetabling problems.     

Adaptive elements of aging: Self-image discrepancy, perfectionism, and eating problems.

Age-related changes in personality variables that may contribute to the reduction of symptoms of eating disorders with adult development were examined. Undergraduate sorority women (n = 52; mean age = 19.85 years) were compared with alumnae of the same sorority (n = 34; mean age = 33.74 years). Eating pathology was correlated with greater discrepancy between the real (current) and the ideal (desired) self-image and with perfectionism. Both self-image discrepancy and perfectionism were markedly lower among the alumnae. Variance in these variables together accounted for the lowered level of eating pathology among the older participants. Specific content domains of the real and ideal self-image and different facets of perfectionism showed distinctive age-related changes and differential relationships with eating pathology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Atomic-volume variations of α-Pu alloyed with Al, Ga, and Am from first-principles theory

First-principles methods are employed to calculate the ground-state atomic densities (or volumes) of α-Pu alloyed with Al, Ga, and Am. Three configurations for the alloying atom are considered. (i) It is located at the most open and energetically most favorably site. (ii) It is located at the least open site. (iii) It is randomly distributed within the α-Pu matrix. When alloyed with Al or Ga, α-Pu behaves similarly, it expands considerably for configurations (ii) and (iii), while for (i) only small changes of the density occur. Interestingly, for Am, the alloying effects are quite different from that of Al and Ga. Small expansion is noted for the ordered configurations (i) and (ii), whereas for the disordered (iii), only insignificant changes of the density take place. The bonding character is thus differently influenced in Pu by the addition of Al and Ga on one hand and Am on the other. This is consistent with the view that Al and Ga stabilize the δ over the α phase in Pu by a different mechanism than Am, as has been discussed in recent publications. The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

Disordering of the Pb (110) surface

Molecular dynamics simulations incorporating a many-body glue model potential (GM) have been used to investigate the atomic structure and dynamics of the Pb (1 1 0) surface in the range from room temperature up to the bulk melting point. The main features of the surface disordering process include: generation of vacancies and the formation of an adlayer, the formation of so-called “local steps” and further their proliferation including wandering, creation and propagation of a quasiliquid surface film. These processes are illustrated by the use of a modern visualization technique.     

DTV (COFDM) SFN signal variation field tests in urban environments for portable outdoor reception

The paper presents the measurement results obtained in an extensive field test campaign developed in two large cities of Spain (Madrid and Bilbao) with the aim of characterizing the portable outdoor reception of digital terrestrial television (COFDM - coded orthogonal frequency division multiplexed) and continue the studies carried out by the authors during the past years.     

From Electronic Structure to Thermodynamics of Actinide-Based Alloys

In this brief review, we show that thermodynamic modeling of complex multicomponent actinide-based alloys is crucial for fuel development and for predicting the impact of evolving fuel chemistry with time on materials performance. With input from energetics and equilibrium properties of alloys from ab initio electronic-structure calculations, within the framework of density-functional theory, the CALPHAD methodology is a viable approach to thermodynamic assessment for this class of materials. Despite the limited availability of experimental thermodynamic data, this approach can predict important features in the phase diagram and, perhaps more importantly, guide and motivate further experiments for validating the methodology and the data for subsequent modeling of materials performance on a higher level.     

Evaluation of elastic properties of DLC layers using resonant ultrasound spectroscopy and AFM nanoindentation

Elastic properties of diamond-like carbon (DLC) layers with gradient carbon–silicon interlayer were studied by resonant ultrasound spectroscopy (RUS) and standard nano-indentation technique. The DLC layers were prepared by pulsed laser deposition on SiC/Si substrates. The RUS method is based on modal analysis of the specimen vibration. The resonant frequency shifts caused by the layer are for the evaluation of the dynamic in-plane elastic properties of the deposited DLC. The results were compared with the quasi-statical quantities — Young's modulus and hardness, obtained by nanoindentation using the AFM tip.