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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.


(a) THz photovoltage as a function of gate voltage under different incidence power. (b) Responsivity curves when incidence polarization is paralle (orange curve) or orthogonal (red curve) respect to the antenna.
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f8: (a) THz photovoltage as a function of gate voltage under different incidence power. (b) Responsivity curves when incidence polarization is paralle (orange curve) or orthogonal (red curve) respect to the antenna.

Mentions: The THz induced photovoltage vs VG is depicted in in Fig. 8a. It is observed that there are obvious peaks and the maximums of the photovoltage happen around −20 ~ −22 V, which are in proximity with Vth in IDS-VG curves. Analysis suggests that this behavior is in accordance with the detection mechanism of a plasmon wave FET detector33, in which the source-drain photovoltage can be expressed as: Where q is the electron charge, ua is the small amplitude of the ac wave, η is the ideality factor, kB is the Boltzmann constant, T is the temperature and UG denotes the gate-to-source voltage minus Vth (UG = VG−Vth), and (here J0 is the gate leakage current density, L is the channel length, m is the electron mass, C is the channel capacitance per unit area, τ is the momentum relaxation time). Under this circumstance, the maximum of the photovoltage: can be derived at the condition when UG = −(ηkBT/2)ln(1/κ). For different J0, UG can be on the range of 0 ~ −5 V33. However precise value of maximum point UG could not be given due to other un-available parameters. Nevertheless, the maximum UG happens around the point VG ≈ Vth with several volts offset, which holds good accordance in the current device data in Fig. 8a. Further, in order to get responsivity values, the following geometric relationship should be taken into account: where RV is the responsivity, Pt is the incidence power impinging on the beam spot, St is the radiation beam spot area and Sa is the active area. St = πd2/4 = 1.77 × 10−6 m2 and Sa = πR2/2 = 1.57 × 10−8 m2 can be easily calculated. However, the antenna scale is much smaller than the wavelength (~ 1 mm). So Sλ = πλ2/4=7.8 × 10−7m2 is taken for the active area. Hence the responsivity spectra at 1000 μW with polarization parallel (orange) and orthogonal (red) to the antenna are plotted in Fig. 8b. Obviously parallel measurement yielded much stronger intensity. which is typically due to much higher THz wave absorption rate of the antenna in parallel geometry. Notably, the peak responsivity of the parallel geometry curve reaches 0.1 V/W.


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)

(a) THz photovoltage as a function of gate voltage under different incidence power. (b) Responsivity curves when incidence polarization is paralle (orange curve) or orthogonal (red curve) respect to the antenna.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4542509&req=5

f8: (a) THz photovoltage as a function of gate voltage under different incidence power. (b) Responsivity curves when incidence polarization is paralle (orange curve) or orthogonal (red curve) respect to the antenna.
Mentions: The THz induced photovoltage vs VG is depicted in in Fig. 8a. It is observed that there are obvious peaks and the maximums of the photovoltage happen around −20 ~ −22 V, which are in proximity with Vth in IDS-VG curves. Analysis suggests that this behavior is in accordance with the detection mechanism of a plasmon wave FET detector33, in which the source-drain photovoltage can be expressed as: Where q is the electron charge, ua is the small amplitude of the ac wave, η is the ideality factor, kB is the Boltzmann constant, T is the temperature and UG denotes the gate-to-source voltage minus Vth (UG = VG−Vth), and (here J0 is the gate leakage current density, L is the channel length, m is the electron mass, C is the channel capacitance per unit area, τ is the momentum relaxation time). Under this circumstance, the maximum of the photovoltage: can be derived at the condition when UG = −(ηkBT/2)ln(1/κ). For different J0, UG can be on the range of 0 ~ −5 V33. However precise value of maximum point UG could not be given due to other un-available parameters. Nevertheless, the maximum UG happens around the point VG ≈ Vth with several volts offset, which holds good accordance in the current device data in Fig. 8a. Further, in order to get responsivity values, the following geometric relationship should be taken into account: where RV is the responsivity, Pt is the incidence power impinging on the beam spot, St is the radiation beam spot area and Sa is the active area. St = πd2/4 = 1.77 × 10−6 m2 and Sa = πR2/2 = 1.57 × 10−8 m2 can be easily calculated. However, the antenna scale is much smaller than the wavelength (~ 1 mm). So Sλ = πλ2/4=7.8 × 10−7m2 is taken for the active area. Hence the responsivity spectra at 1000 μW with polarization parallel (orange) and orthogonal (red) to the antenna are plotted in Fig. 8b. Obviously parallel measurement yielded much stronger intensity. which is typically due to much higher THz wave absorption rate of the antenna in parallel geometry. Notably, the peak responsivity of the parallel geometry curve reaches 0.1 V/W.

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.