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Optimization of self-catalyzed InAs Nanowires on flexible graphite for photovoltaic infrared photodetectors

View Article: PubMed Central - PubMed

ABSTRACT

The recent discovery of flexible graphene monolayers has triggered extensive research interest for the development of III-V/graphene functional hybrid heterostructures. In order to fully exploit their enormous potential in device applications, it is essential to optimize epitaxial growth for the precise control of nanowire geometry and density. Herein, we present a comprehensive growth study of InAs nanowires on graphitic substrates by molecular beam epitaxy. Vertically well-aligned and thin InAs nanowires with high yield were obtained in a narrow growth temperature window of 420–450 °C within a restricted domain of growth rate and V/III flux ratio. The graphitic substrates enable high nanowire growth rates, which is favourable for cost-effective device fabrication. A relatively low density of defects was observed. We have also demonstrated InAs-NWs/graphite heterojunction devices exhibiting rectifying behaviour. Room temperature photovoltaic response with a cut-off wavelength of 3.4 μm was demonstrated. This elucidates a promising route towards the monolithic integration of InAs nanowires with graphite for flexible and functional hybrid devices.

No MeSH data available.


Schematic diagram of the NWs ensemble photodetector (a), bandgap diagram of InAs/Graphite heterojunction (b), I-V curve of a InAs NW ensemble/graphite hybrid device (c), and the room temperature spectral photoresponse of the hybrid device (d). The device mesa has a diameter of 25 μm.
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f5: Schematic diagram of the NWs ensemble photodetector (a), bandgap diagram of InAs/Graphite heterojunction (b), I-V curve of a InAs NW ensemble/graphite hybrid device (c), and the room temperature spectral photoresponse of the hybrid device (d). The device mesa has a diameter of 25 μm.

Mentions: To investigate the electrical properties of as-grown NWs, InAs/Graphite infrared photovoltaic detectors with various mesa diameters of 25–200 μm were fabricated (see Method for device processing). Each mesa contains InAs NW ensambles with an estimated number of over 3000 based on the areal density. The bandgap diagram of the device606162 in thermal equilibrium is shown in Fig. 5(a). The work function of Graphite is around 4.3–4.7 eV69636465, while the Fermi level (EF) of InAs is ~5.0 eV6063. This perspective leads to a downward band bending at the interface of InAs/Graphite which forms a depletion region for the holes. Such a depletion region would enable photodetection. A typical I-V profile of such device is shown in Fig. 5(b). It exhibits an asymmetric rectifying behaviour as expected from InAs/Graphite interface. The spectral photoresponse under the exiting wavelength of 2.4–3.7 μm is shown in Fig. 5(c). A photoresponse with a cut-off wavelength of 3.4 μm clearly implies photodetection from InAs NWs/graphite hybrid junction. The main peak located around 2.7 μm enables the device to work under part of near-infrared and mid-infrared bands.


Optimization of self-catalyzed InAs Nanowires on flexible graphite for photovoltaic infrared photodetectors
Schematic diagram of the NWs ensemble photodetector (a), bandgap diagram of InAs/Graphite heterojunction (b), I-V curve of a InAs NW ensemble/graphite hybrid device (c), and the room temperature spectral photoresponse of the hybrid device (d). The device mesa has a diameter of 25 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5385536&req=5

f5: Schematic diagram of the NWs ensemble photodetector (a), bandgap diagram of InAs/Graphite heterojunction (b), I-V curve of a InAs NW ensemble/graphite hybrid device (c), and the room temperature spectral photoresponse of the hybrid device (d). The device mesa has a diameter of 25 μm.
Mentions: To investigate the electrical properties of as-grown NWs, InAs/Graphite infrared photovoltaic detectors with various mesa diameters of 25–200 μm were fabricated (see Method for device processing). Each mesa contains InAs NW ensambles with an estimated number of over 3000 based on the areal density. The bandgap diagram of the device606162 in thermal equilibrium is shown in Fig. 5(a). The work function of Graphite is around 4.3–4.7 eV69636465, while the Fermi level (EF) of InAs is ~5.0 eV6063. This perspective leads to a downward band bending at the interface of InAs/Graphite which forms a depletion region for the holes. Such a depletion region would enable photodetection. A typical I-V profile of such device is shown in Fig. 5(b). It exhibits an asymmetric rectifying behaviour as expected from InAs/Graphite interface. The spectral photoresponse under the exiting wavelength of 2.4–3.7 μm is shown in Fig. 5(c). A photoresponse with a cut-off wavelength of 3.4 μm clearly implies photodetection from InAs NWs/graphite hybrid junction. The main peak located around 2.7 μm enables the device to work under part of near-infrared and mid-infrared bands.

View Article: PubMed Central - PubMed

ABSTRACT

The recent discovery of flexible graphene monolayers has triggered extensive research interest for the development of III-V/graphene functional hybrid heterostructures. In order to fully exploit their enormous potential in device applications, it is essential to optimize epitaxial growth for the precise control of nanowire geometry and density. Herein, we present a comprehensive growth study of InAs nanowires on graphitic substrates by molecular beam epitaxy. Vertically well-aligned and thin InAs nanowires with high yield were obtained in a narrow growth temperature window of 420–450 °C within a restricted domain of growth rate and V/III flux ratio. The graphitic substrates enable high nanowire growth rates, which is favourable for cost-effective device fabrication. A relatively low density of defects was observed. We have also demonstrated InAs-NWs/graphite heterojunction devices exhibiting rectifying behaviour. Room temperature photovoltaic response with a cut-off wavelength of 3.4 μm was demonstrated. This elucidates a promising route towards the monolithic integration of InAs nanowires with graphite for flexible and functional hybrid devices.

No MeSH data available.