Bipolar phototransistor in a vertical Au/graphene/MoS<sub>2</sub> van der Waals heterojunction with photocurrent enhancement

Jiaqi Li; Xurui Mao; Sheng Xie; Zhaoxin Geng; Hongda Chen

doi:10.1364/PRJ.8.000039

Photonics Research, Volume. 8, Issue 1, 39(2020)

Bipolar phototransistor in a vertical Au/graphene/MoS₂ van der Waals heterojunction with photocurrent enhancement

Jiaqi Li^1,2, Xurui Mao^1、*, Sheng Xie³, Zhaoxin Geng¹, and Hongda Chen¹

¹State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China

²School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China

³School of Microelectronics, Tianjin University, Tianjin 300072, China

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Figures & Tables(8)

Fig. 1. (a) Optical microscope image of the phototransistor device array and the grayscale image of a device. (b) Raman spectrum of the graphene/MoS2 heterojunction under excitation by a 532 nm laser.

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Fig. 2. Production process of the Au/graphene/MoS2 vdWHs bipolar phototransistor.

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Fig. 3. (a) I–V characteristic curve of Au-graphene junction. The Au is the cathode and the graphene layer is the anode. (b) I–V characteristic curve of graphene-MoS2 junction. The graphene is the cathode and the MoS2 is the anode. Band diagrams of the Au/graphene/MoS2 vdWHs (c) in their original state, (d) with forward bias and irradiation.

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Fig. 4. (a) Schematic of the Au/graphene/MoS2 bipolar phototransistor and its equivalent structure. (b) I–V characteristics in darkness and under different irradiance intensity values (VG=0). (c) ICE versus laser power density under different VCE at VG=0 V. (d) VG versus ICE at different VCE with 1.05 mW/cm2 irradiance intensity. The wavelength of the laser is 405 nm.

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Fig. 5. (a) Responsivity of the device as a function of VCE under different VG. (b) Responsivity of the device as a function of laser power density at different VCE. (c) Relationship between photocurrent and dark current, normalized by the ratio Ilaser/Idark, and the detectivity of the bipolar phototransistor at different VCE values (irradiation under 405 nm 0.25 mW/cm2 irradiance intensity and VG=0 V). (d) Responsivity curves of Au/graphene/MoS2 vdWHs under different wavelengths of laser radiation with same laser power density 1.05 mW/cm2.

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Fig. 6. (a) Transient response of the Au/graphene/MoS2 bipolar phototransistor. (b) A section between 80 s and 90 s of (a) with a rise time of 20 ms and a fall time of 92 ms. (c) I–V characteristic curves of graphene/MoS2 vdWHs under irradiation. (d) The photocurrent density of the Au/graphene/MoS2 bipolar phototransistor and graphene/MoS2 photodiode under the same laser power density and the amplification coefficient β depends on the bias voltages. (Irradiation under 405 nm 0.45 mW/cm2 irradiance intensity, VCE=17 V and VG=0 V.)

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Fig. 7. Summary of comparison of the responsivity performance and generation speed of photocurrent of our Au/graphene/MoS2 vdWH with other 2D heterostructures based on MoS2, showing that our device achieves the highest generation speed of photocurrent.

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Table 1. Summary of Comparison of the Au/graphene/ ${MoS}_{2}$ vdWHs with Other 2D Materials Heterostructures Based on Graphene or ${MoS}_{2}$

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Table 1. Summary of Comparison of the Au/graphene/ ${MoS}_{2}$ vdWHs with Other 2D Materials Heterostructures Based on Graphene or ${MoS}_{2}$

Device Materials	Operating Wavelength	Responsivity (A/W)	Detectivity (Jones)	Ref.
$GaTe - {MoS}_{2}$	473 nm	21.83	$8.4 \times 10^{13}$	[43]
${MoS}_{2}$	White	2.5	—	[31]
${WS}_{2} / {MoS}_{2}$	532 nm	2340	$4.1 \times 10^{11}$	[22]
${MoS}_{2}$ &ALD	532 nm	1270	—	[44]
${MoS}_{2}$ homojunction	635 nm	$\approx 70,000$	$3.5 \times 10^{14}$	[45]
$Gr / {MoS}_{2} / Gr$	532 nm	$\approx 10,000$	—	[46]
${Sb}_{2} {Te}_{3} / {MoS}_{2}$	532 nm	360	$1 \times 10^{12}$	[20]
$Au / Gr / {MoS}_{2}$	405 nm	16,458	$1.75 \times 10^{14}$	This work

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Jiaqi Li, Xurui Mao, Sheng Xie, Zhaoxin Geng, Hongda Chen, "Bipolar phototransistor in a vertical Au/graphene/MoS₂ van der Waals heterojunction with photocurrent enhancement," Photonics Res. 8, 39 (2020)

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Paper Information

Category: Optical and Photonic Materials

Received: Sep. 27, 2019

Accepted: Nov. 3, 2019

Published Online: Dec. 16, 2019

The Author Email: Xurui Mao (maoxurui@semi.ac.cn)

DOI:10.1364/PRJ.8.000039

Topics

laser devices and laser physics

Lasers and Laser Optics

Laser physics

laser manufacturing

Instrumentation, Measurement and Metrology

Table 1. Summary of Comparison of the Au/graphene/MoS2 vdWHs with Other 2D Materials Heterostructures Based on Graphene or MoS2

Table 1. Summary of Comparison of the Au/graphene/MoS2 vdWHs with Other 2D Materials Heterostructures Based on Graphene or MoS2

Table 1. Summary of Comparison of the Au/graphene/ ${MoS}_{2}$ vdWHs with Other 2D Materials Heterostructures Based on Graphene or ${MoS}_{2}$

Table 1. Summary of Comparison of the Au/graphene/ ${MoS}_{2}$ vdWHs with Other 2D Materials Heterostructures Based on Graphene or ${MoS}_{2}$