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Terahertz detectors arrays based on orderly aligned InN nanowires.

Chen X, Liu H, Li Q, Chen H, Peng R, Chu S, Cheng B - Sci Rep (2015)

Bottom Line: The InN nanostructures (nanowires and nano-necklaces) were achieved by chemical vapor deposition growth, and then InN nanowires were successfully transferred and aligned into micrometer-sized groups by a "transfer-printing" method.Field effect transistors on aligned nanowires were fabricated and tested for terahertz detection purpose.The detector showed good photoresponse as well as low noise level.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Optoelectronic Materials and Technology, Sun Yat-Sen University, Guangdong Guangzhou 510275, China.

ABSTRACT
Nanostructured terahertz detectors employing a single semiconducting nanowire or graphene sheet have recently generated considerable interest as an alternative to existing THz technologies, for their merit on the ease of fabrication and above-room-temperature operation. However, the lack of alignment in nanostructure device hindered their potential toward practical applications. The present work reports ordered terahertz detectors arrays based on neatly aligned InN nanowires. The InN nanostructures (nanowires and nano-necklaces) were achieved by chemical vapor deposition growth, and then InN nanowires were successfully transferred and aligned into micrometer-sized groups by a "transfer-printing" method. Field effect transistors on aligned nanowires were fabricated and tested for terahertz detection purpose. The detector showed good photoresponse as well as low noise level. Besides, dense arrays of such detectors were also fabricated, which rendered a peak responsivity of 1.1 V/W from 7 detectors connected in series.

No MeSH data available.


TEM and HRTEM images of the InN nanowire and InN nano-necklace.(a) TEM image of the individual nanowire, scale bar: 500 nm, (b) The corresponding HRTEM image and SAED pattern of the nanowire, scale bar: 10 nm. (c) TEM image of the individual nano-necklace, scale bar: 100 nm, (d) The corresponding HRTEM image and FFT pattern of the nano-necklace, scale bar: 10 nm. (e) Space-filling model of ideal [0001] nano-necklace and schematic of a crystal unit of the w-InN with  and {0001} planes enclosed.
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f4: TEM and HRTEM images of the InN nanowire and InN nano-necklace.(a) TEM image of the individual nanowire, scale bar: 500 nm, (b) The corresponding HRTEM image and SAED pattern of the nanowire, scale bar: 10 nm. (c) TEM image of the individual nano-necklace, scale bar: 100 nm, (d) The corresponding HRTEM image and FFT pattern of the nano-necklace, scale bar: 10 nm. (e) Space-filling model of ideal [0001] nano-necklace and schematic of a crystal unit of the w-InN with and {0001} planes enclosed.

Mentions: The chemical composition and microstructure of as-synthesized InN nanostructures were further studied by transmission electron microscope (TEM). The TEM images of single InN nanowire and nano-necklace sample are shown in Fig. 4a,c, respectively. High resolution (HR)-TEM of Fig. 4b is the magnified part of the single nanowire to examine detailed crystal structure. The d-spacing of the lattice fringes measured is 0.28 nm, matching well with the (0001) plane interspacing of wurtzite InN structure. The inset of Fig. 4b shows the corresponding selected area electron diffraction (SAED) pattern taken from the corresponding nanowire, further confirming that the sample is single-crystalline and grows preferentially along the [0001] crystallographic direction. For the InN nano-necklace, Fig. 4c indicates that the nano-necklace consists of multiple single crystalline connected beads, while no grain boundaries between them could be noticed. HRTEM of Fig. 4d (also with fast fourier transfor (FFT) in the inset of Fig. 4d) shows fringe with d-spaces of 0.31 nm. After the TEM studies, the growth pattern of the nano-necklaces can be deduced by the assistance from a w-InN unit cell (Fig. 4e): the growth direction of the nano-necklace is determined to be also [0001]; the equilateral trapezoid facets of the truncated hexagonal beads belong to; the edges between two facets are. By using the standard lattice parameters of w-InN, the angle between two corresponding facets on the opposite sides of the major waist of the beads (e.g. and is calculated to be 124° and that between two corresponding edges (e.g. and ) to be 116°. These are in good agreement with the observed values ranging from 116° to 124° in Fig. 4c. The schematic illustration of the nano-necklace is presented in Fig 4e. The fractions of and planes are not equal, which may owes to the different polarities of them: the former is In-polar while the later is N-terminated. In other words, the as-obtained nano-necklace (see Figs 1 and 4c) are not exactly the same as simulated Fig. 4e; instead, the planes are more favored than the ones, which is due to the different formation energies thus different diffusion abilities of the adatoms on these two types of side-surfaces22. In addition, similar multi-beads morphologies are also observed in one dimensional hexagonal wurtzite stacked-cone and zigzag AlN23, GaN24 and ZnO25 nanostructures.


Terahertz detectors arrays based on orderly aligned InN nanowires.

Chen X, Liu H, Li Q, Chen H, Peng R, Chu S, Cheng B - Sci Rep (2015)

TEM and HRTEM images of the InN nanowire and InN nano-necklace.(a) TEM image of the individual nanowire, scale bar: 500 nm, (b) The corresponding HRTEM image and SAED pattern of the nanowire, scale bar: 10 nm. (c) TEM image of the individual nano-necklace, scale bar: 100 nm, (d) The corresponding HRTEM image and FFT pattern of the nano-necklace, scale bar: 10 nm. (e) Space-filling model of ideal [0001] nano-necklace and schematic of a crystal unit of the w-InN with  and {0001} planes enclosed.
© Copyright Policy - open-access
Related In: Results  -  Collection

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f4: TEM and HRTEM images of the InN nanowire and InN nano-necklace.(a) TEM image of the individual nanowire, scale bar: 500 nm, (b) The corresponding HRTEM image and SAED pattern of the nanowire, scale bar: 10 nm. (c) TEM image of the individual nano-necklace, scale bar: 100 nm, (d) The corresponding HRTEM image and FFT pattern of the nano-necklace, scale bar: 10 nm. (e) Space-filling model of ideal [0001] nano-necklace and schematic of a crystal unit of the w-InN with and {0001} planes enclosed.
Mentions: The chemical composition and microstructure of as-synthesized InN nanostructures were further studied by transmission electron microscope (TEM). The TEM images of single InN nanowire and nano-necklace sample are shown in Fig. 4a,c, respectively. High resolution (HR)-TEM of Fig. 4b is the magnified part of the single nanowire to examine detailed crystal structure. The d-spacing of the lattice fringes measured is 0.28 nm, matching well with the (0001) plane interspacing of wurtzite InN structure. The inset of Fig. 4b shows the corresponding selected area electron diffraction (SAED) pattern taken from the corresponding nanowire, further confirming that the sample is single-crystalline and grows preferentially along the [0001] crystallographic direction. For the InN nano-necklace, Fig. 4c indicates that the nano-necklace consists of multiple single crystalline connected beads, while no grain boundaries between them could be noticed. HRTEM of Fig. 4d (also with fast fourier transfor (FFT) in the inset of Fig. 4d) shows fringe with d-spaces of 0.31 nm. After the TEM studies, the growth pattern of the nano-necklaces can be deduced by the assistance from a w-InN unit cell (Fig. 4e): the growth direction of the nano-necklace is determined to be also [0001]; the equilateral trapezoid facets of the truncated hexagonal beads belong to; the edges between two facets are. By using the standard lattice parameters of w-InN, the angle between two corresponding facets on the opposite sides of the major waist of the beads (e.g. and is calculated to be 124° and that between two corresponding edges (e.g. and ) to be 116°. These are in good agreement with the observed values ranging from 116° to 124° in Fig. 4c. The schematic illustration of the nano-necklace is presented in Fig 4e. The fractions of and planes are not equal, which may owes to the different polarities of them: the former is In-polar while the later is N-terminated. In other words, the as-obtained nano-necklace (see Figs 1 and 4c) are not exactly the same as simulated Fig. 4e; instead, the planes are more favored than the ones, which is due to the different formation energies thus different diffusion abilities of the adatoms on these two types of side-surfaces22. In addition, similar multi-beads morphologies are also observed in one dimensional hexagonal wurtzite stacked-cone and zigzag AlN23, GaN24 and ZnO25 nanostructures.

Bottom Line: The InN nanostructures (nanowires and nano-necklaces) were achieved by chemical vapor deposition growth, and then InN nanowires were successfully transferred and aligned into micrometer-sized groups by a "transfer-printing" method.Field effect transistors on aligned nanowires were fabricated and tested for terahertz detection purpose.The detector showed good photoresponse as well as low noise level.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Optoelectronic Materials and Technology, Sun Yat-Sen University, Guangdong Guangzhou 510275, China.

ABSTRACT
Nanostructured terahertz detectors employing a single semiconducting nanowire or graphene sheet have recently generated considerable interest as an alternative to existing THz technologies, for their merit on the ease of fabrication and above-room-temperature operation. However, the lack of alignment in nanostructure device hindered their potential toward practical applications. The present work reports ordered terahertz detectors arrays based on neatly aligned InN nanowires. The InN nanostructures (nanowires and nano-necklaces) were achieved by chemical vapor deposition growth, and then InN nanowires were successfully transferred and aligned into micrometer-sized groups by a "transfer-printing" method. Field effect transistors on aligned nanowires were fabricated and tested for terahertz detection purpose. The detector showed good photoresponse as well as low noise level. Besides, dense arrays of such detectors were also fabricated, which rendered a peak responsivity of 1.1 V/W from 7 detectors connected in series.

No MeSH data available.