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Optical Properties of GaSb Nanofibers

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ABSTRACT

Amorphous GaSb nanofibers were obtained by ion beam irradiation of bulk GaSb single-crystal wafers, resulting in fibers with diameters of ~20 nm. The Raman spectra and photoluminescence (PL) of the ion irradiation-induced nanofibers before and after annealing were studied. Results show that the Raman intensity of the GaSb LO phonon mode decreased after ion beam irradiation as a result of the formation of the amorphous nanofibers. A new mode is observed at ~155 cm-1 both from the unannealed and annealed GaSb nanofiber samples related to the A1g mode of Sb–Sb bond vibration. Room temperature PL measurements of the annealed nanofibers present a wide feature band at ~1.4–1.6 eV. The room temperature PL properties of the irradiated samples presents a large blue shift compared to bulk GaSb. Annealed nanofibers and annealed nanofibers with Au nanodots present two different PL peaks (400 and 540 nm), both of which may originate from Ga or O vacancies in GaO. The enhanced PL and new band characteristics in nanostructured GaSb suggest that the nanostructured fibers may have unique applications in optoelectronic devices.

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SEM images of GaSb nanofibers. a Under normal Ga+ ion beam bombardment at 30 keV. b With an incident angle of 70°, Ga+ ion beam bombardment at 30 keV. c and d Under normal Kr+ ion beam bombardment at 150 keV.
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Figure 1: SEM images of GaSb nanofibers. a Under normal Ga+ ion beam bombardment at 30 keV. b With an incident angle of 70°, Ga+ ion beam bombardment at 30 keV. c and d Under normal Kr+ ion beam bombardment at 150 keV.

Mentions: Figure 1a, b present in situ scanning electronic microscope (SEM) images showing the morphology of GaSb under 30 keV Ga+ ion beam bombardment with incident angles of 0° and 70°, respectively. Figure 1c, d present SEM images showing the morphology of GaSb with Kr+ irradiation at 150 keV. It was found that the surface quickly evolved into a high density network of uniformly spaced GaSb nanofibers. Parts of the nanofibers were connected together to form a flake-like structure. The diameters of the relatively uniform nanofibers measured by the SEM is ~20 nm (Figure 1a, b). Increasing the irradiation time, which corresponds to an increase in irradiation fluence, decreases the size of the nanofibers. At low fluences, only small voids are formed, as shown in Figure 2a. With continuous bombardment, these voids coalesce and subsequently form fiber-like networks, as shown in Figure 2b. The formation of the GaSb nanofibers can be attributed to the accumulation of atomic damage created by energetic ions [13], with redeposition, viscous flow, and curvature-dependent sputtering also contributing to the morphological evolution of the fibers [17-20].


Optical Properties of GaSb Nanofibers
SEM images of GaSb nanofibers. a Under normal Ga+ ion beam bombardment at 30 keV. b With an incident angle of 70°, Ga+ ion beam bombardment at 30 keV. c and d Under normal Kr+ ion beam bombardment at 150 keV.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3102337&req=5

Figure 1: SEM images of GaSb nanofibers. a Under normal Ga+ ion beam bombardment at 30 keV. b With an incident angle of 70°, Ga+ ion beam bombardment at 30 keV. c and d Under normal Kr+ ion beam bombardment at 150 keV.
Mentions: Figure 1a, b present in situ scanning electronic microscope (SEM) images showing the morphology of GaSb under 30 keV Ga+ ion beam bombardment with incident angles of 0° and 70°, respectively. Figure 1c, d present SEM images showing the morphology of GaSb with Kr+ irradiation at 150 keV. It was found that the surface quickly evolved into a high density network of uniformly spaced GaSb nanofibers. Parts of the nanofibers were connected together to form a flake-like structure. The diameters of the relatively uniform nanofibers measured by the SEM is ~20 nm (Figure 1a, b). Increasing the irradiation time, which corresponds to an increase in irradiation fluence, decreases the size of the nanofibers. At low fluences, only small voids are formed, as shown in Figure 2a. With continuous bombardment, these voids coalesce and subsequently form fiber-like networks, as shown in Figure 2b. The formation of the GaSb nanofibers can be attributed to the accumulation of atomic damage created by energetic ions [13], with redeposition, viscous flow, and curvature-dependent sputtering also contributing to the morphological evolution of the fibers [17-20].

View Article: PubMed Central - HTML

ABSTRACT

Amorphous GaSb nanofibers were obtained by ion beam irradiation of bulk GaSb single-crystal wafers, resulting in fibers with diameters of ~20 nm. The Raman spectra and photoluminescence (PL) of the ion irradiation-induced nanofibers before and after annealing were studied. Results show that the Raman intensity of the GaSb LO phonon mode decreased after ion beam irradiation as a result of the formation of the amorphous nanofibers. A new mode is observed at ~155 cm-1 both from the unannealed and annealed GaSb nanofiber samples related to the A1g mode of Sb–Sb bond vibration. Room temperature PL measurements of the annealed nanofibers present a wide feature band at ~1.4–1.6 eV. The room temperature PL properties of the irradiated samples presents a large blue shift compared to bulk GaSb. Annealed nanofibers and annealed nanofibers with Au nanodots present two different PL peaks (400 and 540 nm), both of which may originate from Ga or O vacancies in GaO. The enhanced PL and new band characteristics in nanostructured GaSb suggest that the nanostructured fibers may have unique applications in optoelectronic devices.

No MeSH data available.