| 1. |
- Slav, A., et al.
(författare)
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Influence of preparation conditions on structure and photosensing properties of GeSi/TiO2 multilayers
- 2017
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Ingår i: 2017 International Semiconductor Conference (CAS). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781509039852 ; , s. 63-66
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Konferensbidrag (refereegranskat)abstract
- The photosensing properties related to the structure of GeSi/TiO2 multilayers prepared under different conditions are studied. TiO2 cap/(GeSi/TiO2)2 multilayers (ML) were deposited by magnetron sputtering (MS) and annealed by rapid thermal annealing. Trilayers of TiO2 cap/GeSi/TiO2 (TL) were also deposited using reactive high power impulse MS (HiPIMS) for TiO2 layers and dc MS for the GeSi layer. For TL samples a two-step annealing was employed, one before and the second after depositing TiO2 cap. Structure and morphology characterization (X-ray diffraction, scanning and transmission electron microscopy) was carried out and photocurrent measurements (voltage dependences, spectral curves) were performed. The annealed ML samples are formed of GeSi NCs with 5-10 nm sizes, while in the annealed TL samples, the GeSi NCs are larger (20-30 nm). These morphologies determine the multilayers photosensing properties in VIS-NIR of ML structures and in UV in TL ones, respectively.
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| 2. |
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| 3. |
- Sultan, M. T., et al.
(författare)
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Enhanced Photoconductivity of SIGE-Trilayer Stack by Retrenching Annealing Conditions
- 2018
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Ingår i: 2018 International Semiconductor Conference (CAS). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538644829 ; , s. 61-64
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Konferensbidrag (refereegranskat)abstract
- We studied the effect of short term furnace annealing over the photoconductive properties of tristacked layer i.e. TiO2/(SiGe/TiO2)3. The structure was prepared by depositing alternate layers of TiO2 and SiGe films, using direct-current magnetron sputtering technique. A transmission electron microscopy and grazing incidence spectroscopy was used to analyze the morphology of the structure. Photoconductive properties were studied by measuring photocurrent spectra at different applied voltages and temperatures. Tristack layers were obtained with 5-10 nm SiGe nanocrystals (NCs) by annealing at 600 °C for 5 min. No sign of SiO2 formation was found inside stacked layers. A maximum in the photocurrent spectra was observed at 994 nm at 300 K but it red-shifted gradually to 1045 nm with decrease in temperature to 100 K. This transition in peak maxima is attributed to SiGe NCs, due to lattice vibration and to contribution of non-radiative recombination at low temperatures.
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| 5. |
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| 6. |
- Sultan, M. T., et al.
(författare)
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Photoluminescence study of Si1-xGex nanoparticles in various oxide matrices
- 2021
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Ingår i: 2021 International Semiconductor Conference (Cas). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 21-24
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Konferensbidrag (refereegranskat)abstract
- We investigate the photoluminescence properties of structures comprising of Si1-xGex nanoparticles (NPs) within SiO2, GeO2, TiO2 and Ta2O5 oxide matrices. Of the investigated structures, it was observed that the structures with GeO2 and TiO2 matrices provide increased spectral response (at similar to 907 and 844 nm respectively) and increased PL intensity. The improved PL characteristic have been attributed to increased diffusion barrier against oxygen which otherwise would result in formation of unwanted oxide at the film-oxide interface, thereby deteriorating the optical properties.
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| 7. |
- Sultan, M. T., et al.
(författare)
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The Effect of H2/Ar Plasma Treatment over Photoconductivity of Sige Nanoparticles Sandwiched between Silicon Oxide Matrix
- 2018
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Ingår i: Proceedings of the International Semiconductor Conference, CAS. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538644829 ; , s. 257-260
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Konferensbidrag (refereegranskat)abstract
- The effect of room temperature hydrogen plasma treatment on the photoconductive properties of the SiO2 matrix containing SiGe nanoparticles is investigated. A considerable increase in photocurrent intensity is observed after plasma treatment. The increase is partly attributed to neutralization of dangling bonds around the nanoparticles and partly to passivation of non-radiative centers and defects in the matrix and at the nanoparticles-matrix interfaces.
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| 8. |
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| 9. |
- Widenkvist, Erika, et al.
(författare)
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Intercalation and Ultrasonic Treatment of Graphite : a New Synthetic Route to Graphene
- 2008
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Konferensbidrag (refereegranskat)abstract
- We will demonstrate that ultrasonic treatment of a graphite crystal in water can lead to the formation of small graphene-like flakes in solution. The delamination of the graphite can be increased dramatically by intercalation of bromine from a Br2-saturated water solution. After ultrasonic treatment, large amounts of graphene-like flakes with varying thickness are observed in SEM and TEM. They can be adsorbed onto a surface of a suitable substrate by a simple dipping technique. The effect of polar and non-polar solvents as well as adsorption of the graphene on hydrophobic and hydrophilic substrates will be demonstrated and compared. DFT calculations of the intercalation process have been carried out using the SIESTA package and the effect of bromine intercalation on cohesive energy and electronic structure will be discussed and compared with experimental data. Finally, the general approach of using ultrasonic treatment and intercalation as a facile route to graphene synthesis compared to other methods will be discussed.
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