The Influence of Oxygen Pressure on the Photoluminescent Properties of Pulsed Laser Ablated SrAl 2O 4:Eu 2+ , Dy 3+ Thin Films
Issue:
Volume 4, Issue 4, August 2016
Pages:
25-31
Received:
29 September 2016
Accepted:
9 October 2016
Published:
31 October 2016
Abstract: SrAl2O4:Eu2+, Dy3+ thin films were prepared using the pulsed laser deposition (PLD) technique and the variation of morphological, photoluminescence and structural properties with the oxygen pressure were studied. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed in the films morphological measurements. The He-Cd 325 nm laser photoluminescence (PL) system and xenon lamp Cary Eclipse fluorescence spectrophotometer were used to collect the photoluminescence and afterglow data. The elemental and depth profile analysis were done by using Auger electron spectroscopy (AES). SrAl2O4:Eu2+, Dy3+ thin films gave a stable green emission peak at 523 nm, attributed to 4f65d1 → 4f7 Eu2+ ransitions. Superior PL and afterglow (AG) properties were recorded by the film deposited at the intermediate oxygen pressure of 0.38 Torr. The film had a rough surface as revealed by the SEM and AFM images. The AES data consisted of all the main elements in SrAl2O4:Eu2+, Dy3+ material, i.e. Sr, Al and O and the adventitious carbon (C). The film thickness varied inversely with the oxygen pressure. The variations of Sr/Al ratios with the PL intensity are reported.
Abstract: SrAl2O4:Eu2+, Dy3+ thin films were prepared using the pulsed laser deposition (PLD) technique and the variation of morphological, photoluminescence and structural properties with the oxygen pressure were studied. The atomic force microscopy (AFM) and scanning electron microscopy (SEM) were employed in the films morphological measurements. The He-Cd...
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Configuration Dependent Electronic and Optical Properties of WZ-CuInS2
Bo Gao,
Fu-Ling Tang,
Hong-Tao Xue,
Fu-Zhen Zhang,
Yu-Wen Cheng
Issue:
Volume 4, Issue 4, August 2016
Pages:
32-39
Received:
15 September 2016
Accepted:
13 October 2016
Published:
3 November 2016
Abstract: We used the first-principles calculations based on density functional theory to calculate the electronic and optical properties of wurtzite CuInS2 (WZ-CuInS2) in which the copper and indium atoms share the same lattice site. It is found that WZ-CuInS2 is metallic for local aggregative indium and copper atomic configurations, or is a semiconductor for local even-distributed configurations. Metallic configurations have higher lattice energies while semi conductive configurations have lower lattice energies. As the degree of the local aggregation of Cu and In atoms increases, the band gap of the WZ-CuInS2 decreases. The optical properties of WZ-CuInS2 were also calculated and found that the optical band gap also decreases as local aggregation of Cu and In atoms with increases. The metallic configurations have a higher absorption coefficient.
Abstract: We used the first-principles calculations based on density functional theory to calculate the electronic and optical properties of wurtzite CuInS2 (WZ-CuInS2) in which the copper and indium atoms share the same lattice site. It is found that WZ-CuInS2 is metallic for local aggregative indium and copper atomic configurations, or is a semiconductor f...
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