Gate-tunable optoelectronic properties of a nano-layered GaSe photodetector

Abderrahmane, Abdelkader; Jung, Pan-Gum; Kim, Nam–Hoon; Ko, Pil Ju; Sandhu, Adarsh

doi:10.1364/ome.7.000587

Cited by 20 publications

(19 citation statements)

References 21 publications

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“…Also, although β increases with decreasing V ds , its value remains always smaller than 1. This is the fingerprint of a photoconductivity gain that is influenced by charge traps in the layers and/or their interfaces . A similar phenomenon was reported in heterostructures based on different vdW crystals, such as WS 2 /MoS 2 and WSe 2 /GaSe heterojunctions …”

Section: Resultssupporting

confidence: 71%

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Xia

Yan

et al. 2019

Advanced Optical Materials

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tunable bandgap energy (from E g = 1.1 to 2.1 eV) and strong light absorption offer opportunities for a variety of optoelectronic devices. [2][3][4] Amongst the TMDs, MoTe 2 is an attractive semiconductor. In the monolayer form, it has a direct bandgap, E g = 1.10 eV at room temperature, larger than that of bulk MoTe 2 , which has an indirect bandgap (E g = 0.85 eV). [5][6][7] Thus, unlike other TMDs, such as MoS 2 and WS 2 , photodetectors based on MoTe 2 can have a broadband photoresponse that extends from the visible (VIS) to the near infrared (NIR) spectral range. [8][9][10] In particular, in MoTe 2 -based field effect transistors (FETs), the photoresponsivity (R) can be enhanced by a photogating effect and achieve values of up to R = 24 mA W −1 under illumination with NIR light. [9] Although Si has a similar bandgap to that of MoTe 2 , its absorption coefficient in the NIR spectral range is smaller than that of MoTe 2 : for Si, the absorption coefficient is 8.17 cm −1 at λ = 1064 nm, which is smaller than that for MoTe 2 (4.9 × 10 4 cm −1 ). [11] In contrast to traditional bulk semiconductors such as Si, Ge, or III-V compounds, 2D vdW crystals have surfaces that are free of dangling bonds. [2] This unique feature arises from their atomic structure: the atoms are arranged into layers that are held together by strong covalent in-plane bonds; in contrast, in the out-of-plane direction, the atomic layers interact with weak vdW interactions. This offers opportunities to combine them with other materials without the limitations of lattice mismatch that apply to covalent crystals. [2,12] For example, MoTe 2 has been used in different multilayer structures: in MoTe 2 /MoS 2 heterojunctions, the on/off photocurrent ratio can reach values of about 780; [13] also, the photoconductive gain in MoTe 2 /graphene heterostructures can be as large as 4.69 × 10 8 . [9] More generally, asymmetric contact barriers between two electrodes and a 2D vdW crystal can be exploited to construct high performance photodetectors: [14][15][16][17][18][19][20][21] Au and In Schottky contacts to a 2D material can be used to realize self-powered photodetectors with high photoresponsivity (R = 110 mA W −1 ). [14] Also, graphene can form a clean interface with 2D materials and its near perfect optical transparency makes it suitable for use as the top electrode of vertical heterostructure photodetectors. [22][23][24][25] Au/MoTe 2 /graphene vertical heterostructures have good photoresponsivity and photoresponse time of about 96 ms. [15] However, the photoresponse of 2D vdW heterostructure devices in the current literature remain still slow due to relatively long optically active Atomically thin 2D materials are promising candidates for miniaturized highperformance optoelectronic devices. This study reports on multilayer MoTe 2 photodetectors contacted with asymmetric electrodes based on n-and p-type graphene layers. The asymmetry in the graphene contacts creates a large (E bi ∼ 100 kV cm −1 ) built-in electric field across the short (l = 15 nm) M...

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Section: Resultssupporting

confidence: 71%

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Xia

Yan

et al. 2019

Advanced Optical Materials

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“…Table 1 lists the values of responsivity ( R ), normalized gain (Γ n ), and detectivity ( D *) of Ga 2 Se 3 together with those of III–VI compounds and transition-metal dichalcogenides (TMDCs) are also included for comparison. For the Ga 2 Se 3 defective-type photoconductor operated at 642 nm, the value of detectivity D * is close to those of the other III–VI GaSe field-effect phototransistors measured at 532 51 and 254 nm 52 of the visible and ultraviolet region, while the responsivity R of Ga 2 Se 3 is slightly larger than that of the layered GaSe, which is not defective type. The high detectivity of the Ga 2 Se 3 implies lower dark current J dark of the photodetector and the value of D * is comparable to its defect semiconductor counterpart, cubic γ-Ga 2 S 3 , operated at 350 nm owing to the larger direct band gap of Ga 2 S 3 .…”

Section: Resultssupporting

confidence: 70%

Ga₂Se₃ Defect Semiconductors: The Study of Direct Band Edge and Optical Properties

2020

ACS Omega

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Direct band edge is a crucial factor for a functional chalcogenide to be applied in luminescence devices, photodetectors, and solar-energy devices. In this work, the room-temperature band-edge emission of III–VI Ga 2 Se 3 has been first observed by micro-photoluminescence (μPL) measurement. The emission peak is at 1.85 eV, which matches well with the band-edge transition that is measured by micro-thermoreflectance (μTR) and micro-transmittance (μTransmittance) for verification of the direct band edge of Ga 2 Se 3 . The temperature-dependent μTR spectra of Ga 2 Se 3 show a general semiconductor behavior with its temperature-energy shift following Varshni-type variation. With the well-evident direct band edge, the peak responsivities of photovoltaic response (∼6.2 mV/μW) and photocurrent (∼2.25 μA/μW at f = 30 Hz) of defect zincblende Ga 2 Se 3 can be, respectively, detected at ∼2.22 and ∼1.92 eV from a Cu/Ga 2 Se 3 Schottky solar cell and a Ga 2 Se 3 photoconductor. On the basis of experimental analysis, the optical band edge and photoresponsivity properties of a III–VI Ga 2 Se 3 defect semiconductor are thus realized.

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“…161,162 However, in FET configuration when integrated as a channel, few-layered GaSe revealed a much lower mobility of 0.1 to 0.6 cm 2 V −1 s −1 . 58,104 Unlike InSe, GaSe is not a high mobility material because of the presence of heavy holes, but it is still very appealing for a variety of optical applications. Because of the absence of inversion symmetry, GaSe is widely used in nonlinear optics.…”

Section: Electronic Propertiesmentioning

confidence: 99%

“…Because of the absence of inversion symmetry, GaSe is widely used in nonlinear optics. 84 Other interesting applications include photodetectors, 104 single-photon emitters, 82 and terahertz applications. 83 Many reports have demonstrated photoactive transistors based on GaSe with high responsivities, indicating its potential in optoelectronics.…”

Section: Electronic Propertiesmentioning

confidence: 99%

Recent progress in contact, mobility, and encapsulation engineering of InSe and GaSe

Arora

Erbe

2020

InfoMat

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The field of two-dimensional (2D) materials has stimulated considerable interest in the scientific community. Owing to quantum confinement in one direction, intriguing properties have been reported in 2D materials that cannot be observed in their bulk form. The advent of semiconducting 2D materials with a broad range of electronic properties has provided fascinating opportunities to design and configure next-generation electronics. One such emerging class is the family of III-VI monochalcogenides, the two prominent members of which are indium selenide (InSe) and gallium selenide (GaSe). In contrast to transition metal dichalcogenides, their high intrinsic mobility and the availability of a direct bandgap at small thicknesses have attracted researchers to investigate the underlying physical phenomena as well as their technological applications. However, the sensitivity of InSe and GaSe to environmental influences has limited their exploitation in functional devices. The lack of methods for their scalable synthesis further hinders the realization of their devices. This review article outlines recent advancements in the synthesis and understanding of the charge transport properties of InSe and GaSe for their integration into technological applications. A detailed summary of the improvements in the device structure by optimizing extrinsic factors such as bottom substrates, metal contacts, and device fabrication schemes is provided. Furthermore, various encapsulation techniques that have been proven effective in preventing the degradation of InSe and GaSe layers under ambient conditions are thoroughly discussed. Finally, this article presents an outlook on future research ventures with respect to ongoing developments and practical viability of these materials.

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Gate-tunable optoelectronic properties of a nano-layered GaSe photodetector

Cited by 20 publications

References 21 publications

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Ga₂Se₃ Defect Semiconductors: The Study of Direct Band Edge and Optical Properties

Recent progress in contact, mobility, and encapsulation engineering of InSe and GaSe

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Gate-tunable optoelectronic properties of a nano-layered GaSe photodetector

Cited by 20 publications

References 21 publications

Enhanced Photoresponse in MoTe2 Photodetectors with Asymmetric Graphene Contacts

Enhanced Photoresponse in MoTe2 Photodetectors with Asymmetric Graphene Contacts

Ga2Se3 Defect Semiconductors: The Study of Direct Band Edge and Optical Properties

Recent progress in contact, mobility, and encapsulation engineering of InSe and GaSe

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Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Ga₂Se₃ Defect Semiconductors: The Study of Direct Band Edge and Optical Properties