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Investigations of ripple pattern formation on Germanium surfaces using 100-keV Ar(+) ions.

Sulania I, Agarwal D, Husain M, Avasthi DK - Nanoscale Res Lett (2015)

Bottom Line: The formation of nanoripples initiates at an angle of θ ~ 45°.Ripple pattern formation has taken place on the Ge surface in the energy regime of 100 keV as compared to the other reports which had been carried out using very low energy ions.Raman spectra reveal that the near surface of crystalline Ge samples becomes amorphous due to interaction of Ar(+) ions due to creation of defects through collision cascades.

View Article: PubMed Central - PubMed

Affiliation: Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 India ; Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India.

ABSTRACT
We have investigated the formation of nanoripples on the surface of germanium, Ge(100), due to the effect of 100-keV Ar (+) ion irradiation. The irradiation was carried out at different incidence angles from 0° to 75° in steps of 15° with respect to the surface normal with a fixed ion fluence of approximately 3 × 10(17) ions/cm(2). Atomic force micrographs show an increase in surface roughness from 0.5 to 4.3 nm for the pristine sample and the sample irradiated at 60° incidence angle due to cos(-1)(θ) dependence on sputtering yield. With increase in angle of incidence, there is transition observed from nanodots to aligned nanodots perpendicular to the direction of the beam. There is an increase in size of the nanostructures observed from 44 to 103 nm with angle of incidence. The formation of nanoripples initiates at an angle of θ ~ 45°. Ripple pattern formation has taken place on the Ge surface in the energy regime of 100 keV as compared to the other reports which had been carried out using very low energy ions. Raman spectra reveal that the near surface of crystalline Ge samples becomes amorphous due to interaction of Ar(+) ions due to creation of defects through collision cascades.

No MeSH data available.


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Raman spectra of the pristine and irradiated Ge samples at different angles.
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Fig5: Raman spectra of the pristine and irradiated Ge samples at different angles.

Mentions: It is well reported in literature that low-energy ion beam irradiation leads to amorphization of surfaces due to creation of point defects through collision cascades, and further irradiation induces the restructuring of the amorphous layer in the form of nanostructures such as dots or ripples depending on the angle of incidence of the ion beam [32]. The thickness of the amorphous layer greatly depends upon the angle of incidence of the ion beam which is qualitatively studied by Raman measurements. Raman spectra of the pristine and irradiated samples are shown in Figure 5. The sharp peak which corresponds to crystalline Ge is visible at 302.5 cm−1 for the pristine sample. The amorphous Ge peaks start to evolve around 268.8 cm−1 for the 0° incidence, and the crystalline peak vanishes as the sample was irradiated with a fluence of 3 × 1017 ions/cm2. The peak is asymmetric in nature. When the irradiation angles were increased further, a little shoulder is observed at approximately 290 cm−1 which may correspond to the nc-Ge peak [33]. The intensity of the shoulder peak decreases monotonically with increase in angle of incidence of the ion beam. This might be due to the change in the thickness of the amorphous layer which is scaling with the intensity of the Raman peak in Figure 5.Figure 5


Investigations of ripple pattern formation on Germanium surfaces using 100-keV Ar(+) ions.

Sulania I, Agarwal D, Husain M, Avasthi DK - Nanoscale Res Lett (2015)

Raman spectra of the pristine and irradiated Ge samples at different angles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385137&req=5

Fig5: Raman spectra of the pristine and irradiated Ge samples at different angles.
Mentions: It is well reported in literature that low-energy ion beam irradiation leads to amorphization of surfaces due to creation of point defects through collision cascades, and further irradiation induces the restructuring of the amorphous layer in the form of nanostructures such as dots or ripples depending on the angle of incidence of the ion beam [32]. The thickness of the amorphous layer greatly depends upon the angle of incidence of the ion beam which is qualitatively studied by Raman measurements. Raman spectra of the pristine and irradiated samples are shown in Figure 5. The sharp peak which corresponds to crystalline Ge is visible at 302.5 cm−1 for the pristine sample. The amorphous Ge peaks start to evolve around 268.8 cm−1 for the 0° incidence, and the crystalline peak vanishes as the sample was irradiated with a fluence of 3 × 1017 ions/cm2. The peak is asymmetric in nature. When the irradiation angles were increased further, a little shoulder is observed at approximately 290 cm−1 which may correspond to the nc-Ge peak [33]. The intensity of the shoulder peak decreases monotonically with increase in angle of incidence of the ion beam. This might be due to the change in the thickness of the amorphous layer which is scaling with the intensity of the Raman peak in Figure 5.Figure 5

Bottom Line: The formation of nanoripples initiates at an angle of θ ~ 45°.Ripple pattern formation has taken place on the Ge surface in the energy regime of 100 keV as compared to the other reports which had been carried out using very low energy ions.Raman spectra reveal that the near surface of crystalline Ge samples becomes amorphous due to interaction of Ar(+) ions due to creation of defects through collision cascades.

View Article: PubMed Central - PubMed

Affiliation: Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi, 110067 India ; Jamia Millia Islamia, Jamia Nagar, New Delhi, 110025 India.

ABSTRACT
We have investigated the formation of nanoripples on the surface of germanium, Ge(100), due to the effect of 100-keV Ar (+) ion irradiation. The irradiation was carried out at different incidence angles from 0° to 75° in steps of 15° with respect to the surface normal with a fixed ion fluence of approximately 3 × 10(17) ions/cm(2). Atomic force micrographs show an increase in surface roughness from 0.5 to 4.3 nm for the pristine sample and the sample irradiated at 60° incidence angle due to cos(-1)(θ) dependence on sputtering yield. With increase in angle of incidence, there is transition observed from nanodots to aligned nanodots perpendicular to the direction of the beam. There is an increase in size of the nanostructures observed from 44 to 103 nm with angle of incidence. The formation of nanoripples initiates at an angle of θ ~ 45°. Ripple pattern formation has taken place on the Ge surface in the energy regime of 100 keV as compared to the other reports which had been carried out using very low energy ions. Raman spectra reveal that the near surface of crystalline Ge samples becomes amorphous due to interaction of Ar(+) ions due to creation of defects through collision cascades.

No MeSH data available.


Related in: MedlinePlus