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Structural and Optical Property of High Quality GaN Thin Film on Si with ZnO Buffer Layer
Jianting He,
Shulian Yang,
Qinqin Wei
Issue:
Volume 5, Issue 1, June 2019
Pages:
1-4
Received:
29 January 2019
Accepted:
17 March 2019
Published:
8 April 2019
Abstract: A method was applied to improve the crystallization quality of GaN. ZnO thin films were deposited on n-Si (111) at 600°C by pulsed laser deposition (PLD), and GaN thin films were grown on Si or ZnO/ Si by R. F. magnetron sputtering system. Several GaN films were prepared with ZnO as buffer layer without annealing, with ZnO as buffer layer annealed at 850°C, 900°C and 950°C and with no buffer layer annealed at 950°C, respectively. The crystallization, optical property and morphology of all GaN films prepared were studied by X-ray diffraction (XRD), Fourier transform infrared spectrophotometer (FTIR), photoluminescence (PL) and scanning electron microscope (SEM). The results show that ZnO buffer layer plays an important role in improving the crystallization quality of GaN.
Abstract: A method was applied to improve the crystallization quality of GaN. ZnO thin films were deposited on n-Si (111) at 600°C by pulsed laser deposition (PLD), and GaN thin films were grown on Si or ZnO/ Si by R. F. magnetron sputtering system. Several GaN films were prepared with ZnO as buffer layer without annealing, with ZnO as buffer layer annealed ...
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Effect of Thickness and Composition Ratio of Poly(3-Hexylthiophene) and [6,6]-Phenyl C60-Butyric Acid Methyl Ester Thin Film on Optical Absorption for Organic Solar Cell Fabrication
Sunday Wilson Balogun,
Yekini Kolawole Sanusi
Issue:
Volume 5, Issue 1, June 2019
Pages:
5-10
Received:
21 February 2019
Accepted:
4 April 2019
Published:
6 May 2019
Abstract: A Blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C60-butyric acid methyl ester (PCBM), a fullerene derivate based donor-acceptor copolymer, is one of the widely used organic solar cell materials for photon-electron conversion. Thin films were developed, characterized, and optimized for optical absorbance. Absorption spectra were measured using a UV-VIS spectrophotometer. In this work, the effects of composition ratios of P3HT:PC60BM and various thicknesses was studied in ambient conditions. The P3HT:PC61BM thin film was deposited in two different composition ratio (1:1 and 1:3) and fabricated at seven different thicknesses of 20 nm, 30 nm, 35 nm, 87 nm, 98 nm, 115 nm, and 146 nm corresponding to spin coating speeds of 4000rpm, 3000rpm, 2000rpm, 1500rpm, 1250rpm, 1000rpm, and 750rpm, respectively. P3HT:PC60BM thin film composition ratio of 1:1 with thickness of 87nm shows relatively better photon absorption optical parameter than P3HT:PC60BM composition ratio of 1:3. P3HT: PC61BM solution coated at a spin speed of 1500 rpm shows a better absorption of photon energy. The results showed that the optimum thickness of the thin film is 87 nm at composition ratio of 1:1. Energy band gap values of composition ratio of 1:3 is observed to decreases with increase in spin- speed from 3.9 eV to 3.7 eV. The results can be used as a guideline for improving the design and fabrication of active layer of organic solar cells.
Abstract: A Blend of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C60-butyric acid methyl ester (PCBM), a fullerene derivate based donor-acceptor copolymer, is one of the widely used organic solar cell materials for photon-electron conversion. Thin films were developed, characterized, and optimized for optical absorbance. Absorption spectra were measured u...
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Laser-Induced Fluorescence of Wet Porous Silicon as Laser-Induced Fluorescence of H3O+
Issue:
Volume 5, Issue 1, June 2019
Pages:
11-15
Received:
7 March 2019
Accepted:
12 April 2019
Published:
20 May 2019
Abstract: Typically, the production of porous silicon is an electrochemical etching of monocrystalline silicon wafers, which are connected to the anode, in ethanol-aqueous HF solutions. In the process of etching, it turns out porous silicon, which is saturated with water, which is rich in protonated molecules H3O+, formed as a result of a number of well-known physicochemical processes. At the same time, the presence of molecules of such protonated water in the composition of freshly prepared porous silicon is usually ignored. At the same time, both the ability of protonated water to fluoresce under the action of laser radiation in the UV range, and the possible contribution of such fluorescence to the total fluorescence of porous silicon induced by a UV laser is ignored. Since such ignoring seems to be incorrect, the possible contribution of laser fluorescence of water enriched with its protonated molecules to the laser fluorescence of moistened porous silicon is discussed here. Since this may be important for the correct interpretation of the results obtained when studying the spectra of laser-induced fluorescence of porous silicon moistened with aqueous solutions, in particular – with aqueous solutions of biological substances, the unique properties of such water are also demonstrated. Thus, the exceptional penetrating ability of positively charged water is visualized, due to which it is able to transfer from the hydrated shells of biopolymers to porous silicon and enhance its laser-induced fluorescence. It also demonstrates the exceptional ability of positively charged water to evaporate; which makes it possible to explain the rapid disappearance of the fluorescence of porous silicon, which is observed during its drying.
Abstract: Typically, the production of porous silicon is an electrochemical etching of monocrystalline silicon wafers, which are connected to the anode, in ethanol-aqueous HF solutions. In the process of etching, it turns out porous silicon, which is saturated with water, which is rich in protonated molecules H3O+, formed as a result of a number of well-know...
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Light Dispersion in Diamond-like Crystals
Issue:
Volume 5, Issue 1, June 2019
Pages:
16-23
Received:
2 May 2019
Accepted:
3 June 2019
Published:
18 June 2019
Abstract: Dispersion of light in diamond-like crystals is investigated. Dispersion laws of exciton polaritons in this structures, which (apart from the diamond itself) include silicon and germanium is obtained within the quasi-molecular model of valent crystals. Dispersion curves point to the fact that in the vicinity of exciton resonance under small damping one must account for the exciton-photon interaction. The calculation shows that in a certain frequency range the existence of an additional light wave is possible. The dispersion laws of exciton polaritons in a diamond-like structure in the vicinity of frequency of the lowest dipole transition of a crystalline quasi-molecule (a σ-bond) are obtained.
Abstract: Dispersion of light in diamond-like crystals is investigated. Dispersion laws of exciton polaritons in this structures, which (apart from the diamond itself) include silicon and germanium is obtained within the quasi-molecular model of valent crystals. Dispersion curves point to the fact that in the vicinity of exciton resonance under small damping...
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