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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) IDS vs VDS curve of the FET device under different VG. (b) IDS vs VDS curve when VDS kept at 0.5 V.
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f7: (a) IDS vs VDS curve of the FET device under different VG. (b) IDS vs VDS curve when VDS kept at 0.5 V.

Mentions: With the above device geometry, FET characterizations on a single array which consists of 5 InN nanowires were performed at room temperature. The source-drain current (IDS) versus source-drain voltage (VDS) curves under different gate voltages (VG) −10 V to 10 V is shown in Fig. 7a. IDS increases with the increase of VG evidently, suggesting typical n-type channel characteristics29. Fig. 7b shows the IDS-VG transfer curve at VDS = 0.5 V. It is observed that the IDS increases with the increase of VG from −30 V to 30 V, which is in accordance with Fig. 7a. It is notes that with high VG, IDS increase becomes nonlinear, which is possibly due to high current (~ 30 μA in one nanowire) annealing effect. Also the corresponding IDS at given VG is not well matched between Fig 7a,b, which is attributed to the hysteresis behavior of the IDS-VG curve. Unlike ZnO nanowire FETs29 or carbon nanotubes30, the device does not exhibit very clear and high on/off ratio. The reason is due to residue carrier density that not swept by VG. The threshold voltage (Vth) is found to be about −25 V ~ −30 V. In a nanowire FET, the carrier concentration n can be estimated by using the following equation31: where L, d, Vth, and q are the channel length (~ 1 μm), the nanowire diameter (averagely 200 nm), the threshold voltage of the nanowire FET (equals to −25 ~ −30 V), and the elementary charge constant q = −1.6 × 10−19 C, respectively. C is the capacitance of the FET device, which is modeled by electrostatic module of Comsol Multiphysics (COMSOL Inc.) to be 4.07 × 1017 F. It is assumed that InN nanowires are with similar electrical properties and it can be assumed that the Vth are the same for the analysis. From the equation, the electron concentration is calculated to be 3.64 ~ 4.36 × 1017 cm−3. The mobility can be calculated through the following equation31: where L = 1 μm is the channel length (gate length); VDS = 0.5 V; transconductance from the linear region of the IDS-VG curve. After all, the mobility of 99 cm2/VS could be calculated by equation (2), which is on the same order with reported InAs nanowire THz detectors (~ 500 cm2/VS)32.


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) IDS vs VDS curve of the FET device under different VG. (b) IDS vs VDS curve when VDS kept at 0.5 V.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f7: (a) IDS vs VDS curve of the FET device under different VG. (b) IDS vs VDS curve when VDS kept at 0.5 V.
Mentions: With the above device geometry, FET characterizations on a single array which consists of 5 InN nanowires were performed at room temperature. The source-drain current (IDS) versus source-drain voltage (VDS) curves under different gate voltages (VG) −10 V to 10 V is shown in Fig. 7a. IDS increases with the increase of VG evidently, suggesting typical n-type channel characteristics29. Fig. 7b shows the IDS-VG transfer curve at VDS = 0.5 V. It is observed that the IDS increases with the increase of VG from −30 V to 30 V, which is in accordance with Fig. 7a. It is notes that with high VG, IDS increase becomes nonlinear, which is possibly due to high current (~ 30 μA in one nanowire) annealing effect. Also the corresponding IDS at given VG is not well matched between Fig 7a,b, which is attributed to the hysteresis behavior of the IDS-VG curve. Unlike ZnO nanowire FETs29 or carbon nanotubes30, the device does not exhibit very clear and high on/off ratio. The reason is due to residue carrier density that not swept by VG. The threshold voltage (Vth) is found to be about −25 V ~ −30 V. In a nanowire FET, the carrier concentration n can be estimated by using the following equation31: where L, d, Vth, and q are the channel length (~ 1 μm), the nanowire diameter (averagely 200 nm), the threshold voltage of the nanowire FET (equals to −25 ~ −30 V), and the elementary charge constant q = −1.6 × 10−19 C, respectively. C is the capacitance of the FET device, which is modeled by electrostatic module of Comsol Multiphysics (COMSOL Inc.) to be 4.07 × 1017 F. It is assumed that InN nanowires are with similar electrical properties and it can be assumed that the Vth are the same for the analysis. From the equation, the electron concentration is calculated to be 3.64 ~ 4.36 × 1017 cm−3. The mobility can be calculated through the following equation31: where L = 1 μm is the channel length (gate length); VDS = 0.5 V; transconductance from the linear region of the IDS-VG curve. After all, the mobility of 99 cm2/VS could be calculated by equation (2), which is on the same order with reported InAs nanowire THz detectors (~ 500 cm2/VS)32.

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.