Articles you may be interested inPhotoluminescence properties and crystallization of silicon quantum dots in hydrogenated amorphous Si-rich silicon carbide films Effect of thickness on the photoluminescence of silicon quantum dots embedded in silicon nitride films Low-temperature synthesis of homogeneous nanocrystalline cubic silicon carbide films J. Appl. Phys. 102, 056101 (2007); 10.1063/1.2776155 H-induced effects in luminescent silicon nanostructures obtained from plasma enhanced chemical vapor deposition grown Si y O 1 − y : H ( y > 1 ∕ 3 ) thin films annealed in ( Ar + 5 % H 2 )A moderately low temperature (≤800 • C) thermal processing technique has been described for the growth of the silicon quantum dots (Si-QD) within microcrystalline silicon carbide (µc-SiC:H) dielectric thin films deposited by plasma enhanced chemical vapour deposition (PECVD) process. The nanocrystalline silicon grains (nc-Si) present in the as deposited films were initially enhanced by aluminium induced crystallization (AIC) method in vacuum at a temperature of T v = 525 • C. The samples were then stepwise annealed at different temperatures T a in air ambient. Analysis of the films by FTIR and XPS reveal a rearrangement of the µc-SiC:H network has taken place with a significant surface oxidation of the nc-Si domains upon annealing in air. The nc-Si grain size (D XRD ) as calculated from the XRD peak widths using Scherrer formula was found to decrease from 7 nm to 4 nm with increase in T a from 250 • C to 800 • C. A core shell like structure with the nc-Si as the core and the surface oxide layer as the shell can clearly describe the situation. The results indicate that with the increase of the annealing temperature in air the oxide shell layer becomes thicker and the nc-Si cores become smaller until their size reduced to the order of the Si-QDs. Quantum confinement effect due to the SiO covered nc-Si grains of size about 4 nm resulted in a photoluminescence peak due to the Si QDs with peak energy at 1.8 eV. C 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
Al doped ZnO films have been grown by pulsed laser deposition (PLD) technique using ceramic targets sintered at different temperatures in the range 800 o C to 1400 o C. The effect of target sintering temperature on the structural, optical and electrical properties of the AZO films has been investigated. The X-ray diffraction (XRD) patterns show that besides the major hexagonal wurtzite phase of ZnO, the zinc aluminate (ZnAl 2 O 4 ) spinel impurity phase is present predominantly in the targets sintered at 900 o C onwards. The XRD peak intensity of the spinel phase increases as the sintering temperature increases. Although, no such impurity has been primarily appeared in the XRD pattern of the films deposited from these targets, the presence of a probable spinel phase has been sensed by the X-ray photoelectron spectroscopy (XPS) measurements. All the films show more than 90% transparency in the region 500 nm to 1400 nm.The electrical resistance of the target pellets also decreases with an increase in the sintering temperature up to 1100 o C and then increases. Similarly, the carrier concentration increases and the resistivity decreases with the sintering temperature attaining the values of 6.36×10 20 cm -3 and 6.38×10 -4 ohm-cm respectively for the films ablated from the targets sintered at temperatures 1000 o C (AZO1000) and 1100 o C (AZO1100) beyond which both the values deteriorate. An increase in the carrier concentration value is assigned to the modification of the grain boundaries by the spinel phase. Vacuum annealing of AZO1000 film at 350 o C results in a further increase in the carrier concentration to a value of 1×10 21 cm -3 . This film has been applied as a transparent electrode without texturing for a-Si:H solar cell which shows a conversion efficiency of ~3.93%.Our study for the first time shows that the presence of a ZnAl 2 O 4 phase to a certain extent in AZO film rather helps to achieve higher carrier concentration.
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