Cu(In,Ga,Al)Se-2 (CIGAS) thin films were studied as an alternative absorber layer material to Cu(InxGa1-x)Se-2. CIGAS thin films with varying Al content were prepared by magnetron sputtering on Si(100) and soda-lime glass substrates at 350 degrees C, followed by postdeposition annealing at 520 degrees C for 5 h in vacuum. The film composition was measured by an electron probe micro-analyzer while the elemental depth profiles were determined by secondary ion mass spectrometry. X-ray diffraction studies indicated that CIGAS films are single phase with chalcopyrite structure and that the (112) peak clearly shifts to higher 2 theta values with increasing Al content. Scanning electron microscopy images revealed dense and well-defined grains, as well as sharp CIGAS/Si(100) interfaces for all films. Atomic force microscopy analysis indicated that the roughness of CIGAS films decreases with increasing Al content. The bandgap of CIGAS films was determined from the optical transmittance and reflectance spectra and was found to increase as Al content increased. (C) 2015 American Vacuum Society.

We give a new proof of a theorem of Mansour and Sun by using number theory and Rothe's identity. (c) 2007 Elsevier Ltd. All rights reserved.

Divided differences is a very important tool, often used both in theory and in practice, for the approximation of functions. In this paper, we employ divided differences with repetitions to find a general explicit formula for the sequences satisfying Mansour-Mulay-Shattuck's two-term recurrence with arbitrary (b(i))(i >= 0). (C) 2013 Elsevier Inc. All rights reserved.