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Evolution of morphology and microstructure of GaAs/GaSb nanowire heterostructures.

Shi S, Zhang Z, Lu Z, Shu H, Chen P, Li N, Zou J, Lu W - Nanoscale Res Lett (2015)

Bottom Line: The as-grown GaSb shell layer forms a wurtzite structure instead of the zinc blende structure that has been commonly reported.Meanwhile, a bulgy GaSb nanoplate also appears on top of GaAs/GaSb core-shell NWs and possesses a pure zinc blende phase.The growth mode for core-shell morphology and underlying mechanism for crystal phase selection of GaAs/GaSb nanowire heterostructures are discussed in detail.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai, 200083 China.

ABSTRACT
In this paper, we successfully grow GaAs/GaSb core-shell heterostructure nanowires (NWs) by molecular beam epitaxy (MBE). The as-grown GaSb shell layer forms a wurtzite structure instead of the zinc blende structure that has been commonly reported. Meanwhile, a bulgy GaSb nanoplate also appears on top of GaAs/GaSb core-shell NWs and possesses a pure zinc blende phase. The growth mode for core-shell morphology and underlying mechanism for crystal phase selection of GaAs/GaSb nanowire heterostructures are discussed in detail.

No MeSH data available.


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SEM images of GaAs/GaSb heterostructure NWs grown at different V/III ratios. (a) V/III = 0.8, (b) V/III = 1.3, (c) V/III = 2.1, and (d) V/III = 6.5, respectively.
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Fig1: SEM images of GaAs/GaSb heterostructure NWs grown at different V/III ratios. (a) V/III = 0.8, (b) V/III = 1.3, (c) V/III = 2.1, and (d) V/III = 6.5, respectively.

Mentions: Figure 1 shows tilted SEM images of NWs grown at different V/III BEP ratios. When the V/III BEP ratio is 0.8 (Figure 1a), NWs manifest very irregular orientations, and they usually stick together. Meanwhile, the obvious substrate surface irregularity suggests the 2-D thin film growth on the GaAs substrate. Then, when the V/III BEP ratio is increased to 1.3, most NWs grow vertically on the GaAs substrate, as can be observed in Figure 1b, in which most of NWs can be divided into two segments with different diameters. In fact, the upper thicker NW segment has a faceted shape. NWs grown at the V/III BEP ratio of 2.1 (Figure 1c) and 6.5 (Figure 1d) have a basically similar morphology as NWs shown in Figure 1b, but displays a more obvious tendency of lateral growth. The two-segment morphology of GaAs/GaSb NWs grown at higher V/III ratios provides a useful method to distinguish GaAs and GaSb contributions. For the lower thin NW segments, the average diameter for NWs in Figure 1b, c, d can be estimated as 45 nm from which we anticipate that the lower thinner segment should be GaAs NWs, since all GaAs NWs in these three samples were grown under the same conditions. On this basis, the upper thick segment should be caused by the GaSb growth, at least partially. This agrees with the previous report on the GaSb NW growth, in which lateral growth of GaSb NWs can be enhanced by increasing the V/III ratio [30]. Surprisingly, we do not find obvious Au catalyst particles residing on top of GaAs/GaSb core-shell NWs for all four samples.Figure 1


Evolution of morphology and microstructure of GaAs/GaSb nanowire heterostructures.

Shi S, Zhang Z, Lu Z, Shu H, Chen P, Li N, Zou J, Lu W - Nanoscale Res Lett (2015)

SEM images of GaAs/GaSb heterostructure NWs grown at different V/III ratios. (a) V/III = 0.8, (b) V/III = 1.3, (c) V/III = 2.1, and (d) V/III = 6.5, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385115&req=5

Fig1: SEM images of GaAs/GaSb heterostructure NWs grown at different V/III ratios. (a) V/III = 0.8, (b) V/III = 1.3, (c) V/III = 2.1, and (d) V/III = 6.5, respectively.
Mentions: Figure 1 shows tilted SEM images of NWs grown at different V/III BEP ratios. When the V/III BEP ratio is 0.8 (Figure 1a), NWs manifest very irregular orientations, and they usually stick together. Meanwhile, the obvious substrate surface irregularity suggests the 2-D thin film growth on the GaAs substrate. Then, when the V/III BEP ratio is increased to 1.3, most NWs grow vertically on the GaAs substrate, as can be observed in Figure 1b, in which most of NWs can be divided into two segments with different diameters. In fact, the upper thicker NW segment has a faceted shape. NWs grown at the V/III BEP ratio of 2.1 (Figure 1c) and 6.5 (Figure 1d) have a basically similar morphology as NWs shown in Figure 1b, but displays a more obvious tendency of lateral growth. The two-segment morphology of GaAs/GaSb NWs grown at higher V/III ratios provides a useful method to distinguish GaAs and GaSb contributions. For the lower thin NW segments, the average diameter for NWs in Figure 1b, c, d can be estimated as 45 nm from which we anticipate that the lower thinner segment should be GaAs NWs, since all GaAs NWs in these three samples were grown under the same conditions. On this basis, the upper thick segment should be caused by the GaSb growth, at least partially. This agrees with the previous report on the GaSb NW growth, in which lateral growth of GaSb NWs can be enhanced by increasing the V/III ratio [30]. Surprisingly, we do not find obvious Au catalyst particles residing on top of GaAs/GaSb core-shell NWs for all four samples.Figure 1

Bottom Line: The as-grown GaSb shell layer forms a wurtzite structure instead of the zinc blende structure that has been commonly reported.Meanwhile, a bulgy GaSb nanoplate also appears on top of GaAs/GaSb core-shell NWs and possesses a pure zinc blende phase.The growth mode for core-shell morphology and underlying mechanism for crystal phase selection of GaAs/GaSb nanowire heterostructures are discussed in detail.

View Article: PubMed Central - PubMed

Affiliation: National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, 500 Yu Tian Road, Shanghai, 200083 China.

ABSTRACT
In this paper, we successfully grow GaAs/GaSb core-shell heterostructure nanowires (NWs) by molecular beam epitaxy (MBE). The as-grown GaSb shell layer forms a wurtzite structure instead of the zinc blende structure that has been commonly reported. Meanwhile, a bulgy GaSb nanoplate also appears on top of GaAs/GaSb core-shell NWs and possesses a pure zinc blende phase. The growth mode for core-shell morphology and underlying mechanism for crystal phase selection of GaAs/GaSb nanowire heterostructures are discussed in detail.

No MeSH data available.


Related in: MedlinePlus