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Single-crystalline chromium silicide nanowires and their physical properties.

Hsu HF, Tsai PC, Lu KC - Nanoscale Res Lett (2015)

Bottom Line: Processing parameters, including the temperature of Si (100) substrates and precursors, the gas flow rate, the heating time, and the different flow gas of reactions were varied and studied; additionally, the physical properties of the chromium disilicide nanowires were measured.It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere.This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Rd, Tainan, 701 Taiwan.

ABSTRACT
In this work, chromium disilicide nanowires were synthesized by chemical vapor deposition (CVD) processes on Si (100) substrates with hydrous chromium chloride (CrCl3 · 6H2O) as precursors. Processing parameters, including the temperature of Si (100) substrates and precursors, the gas flow rate, the heating time, and the different flow gas of reactions were varied and studied; additionally, the physical properties of the chromium disilicide nanowires were measured. It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere. The crystal structure and growth direction were identified, and the growth mechanism was proposed as well. This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

No MeSH data available.


PL spectrum for the CrSi2nanowires. (a) Energy states of CrSi2 bulk. (b) Photoluminescence measurements of CrSi2 NWs with Gaussian fitting.
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Fig8: PL spectrum for the CrSi2nanowires. (a) Energy states of CrSi2 bulk. (b) Photoluminescence measurements of CrSi2 NWs with Gaussian fitting.

Mentions: On photoluminescence analysis, Bhamu et al. studied the density of state (DOS) of CrSi2 bulk, including 1.33 eV, 0.56 eV above Fermi state, and 2.23 eV under Fermi state [29]. Figure 8b shows our PL spectrum in the visible region for the CrSi2 nanowires, where the wide peak was present (red line) and through Gaussian fitting; the other two peaks, 396 nm (green line) and 465 nm (blue line), were calculated. Theoretically, the electron-hole pair recombinations of 1.33 eV, 0.56 eV conduct state to −2.23 eV valance state were 348 and 430 nm for CrSi2 bulk. In reality, the difference results from dimension, bulk, and nanowires; as the particle size reduces, wider bandgap light absorption band will move to shorter wavelengths, which is so-called blueshift [30]; however, there may be redshift as well; as the particle size decreases, the internal stress will increase, causing changes in the band structure [31] and the electron wave function overlap to increase the energy gap narrowing [32]; if the redshift factor is larger than the blueshift, then we will see redshift phenomenon, which is the case here.Figure 8


Single-crystalline chromium silicide nanowires and their physical properties.

Hsu HF, Tsai PC, Lu KC - Nanoscale Res Lett (2015)

PL spectrum for the CrSi2nanowires. (a) Energy states of CrSi2 bulk. (b) Photoluminescence measurements of CrSi2 NWs with Gaussian fitting.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385120&req=5

Fig8: PL spectrum for the CrSi2nanowires. (a) Energy states of CrSi2 bulk. (b) Photoluminescence measurements of CrSi2 NWs with Gaussian fitting.
Mentions: On photoluminescence analysis, Bhamu et al. studied the density of state (DOS) of CrSi2 bulk, including 1.33 eV, 0.56 eV above Fermi state, and 2.23 eV under Fermi state [29]. Figure 8b shows our PL spectrum in the visible region for the CrSi2 nanowires, where the wide peak was present (red line) and through Gaussian fitting; the other two peaks, 396 nm (green line) and 465 nm (blue line), were calculated. Theoretically, the electron-hole pair recombinations of 1.33 eV, 0.56 eV conduct state to −2.23 eV valance state were 348 and 430 nm for CrSi2 bulk. In reality, the difference results from dimension, bulk, and nanowires; as the particle size reduces, wider bandgap light absorption band will move to shorter wavelengths, which is so-called blueshift [30]; however, there may be redshift as well; as the particle size decreases, the internal stress will increase, causing changes in the band structure [31] and the electron wave function overlap to increase the energy gap narrowing [32]; if the redshift factor is larger than the blueshift, then we will see redshift phenomenon, which is the case here.Figure 8

Bottom Line: Processing parameters, including the temperature of Si (100) substrates and precursors, the gas flow rate, the heating time, and the different flow gas of reactions were varied and studied; additionally, the physical properties of the chromium disilicide nanowires were measured.It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere.This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Cheng Kung University, No.1, University Rd, Tainan, 701 Taiwan.

ABSTRACT
In this work, chromium disilicide nanowires were synthesized by chemical vapor deposition (CVD) processes on Si (100) substrates with hydrous chromium chloride (CrCl3 · 6H2O) as precursors. Processing parameters, including the temperature of Si (100) substrates and precursors, the gas flow rate, the heating time, and the different flow gas of reactions were varied and studied; additionally, the physical properties of the chromium disilicide nanowires were measured. It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere. The crystal structure and growth direction were identified, and the growth mechanism was proposed as well. This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

No MeSH data available.