Photoquantum Hall Effect and Light‐Induced Charge Transfer at the Interface of Graphene/InSe Heterostructures

Bhuiyan, Mahabub Alam; Kudrynskyi, Z. R.; Mazumder, Debarati; Greener, Jake D. G.; Makarovsky, O.; Mellor, Christopher J.; Вдовин, Е. Е.; Piot, B. A.; Lobanova, I. I.; Kovalyuk, Zakhar D.; Nazarova, Marina; Mishchenko, Artem; Novoselov, Kostya S.; Cao, Yang; Eaves, L.; Yusa, Go; Patanè, A.

doi:10.1002/adfm.201805491

Cited by 23 publications

(26 citation statements)

References 32 publications

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“…By fitting the rising and falling edges of the current versus time in Figure c, we derive τ r = 16.58 µs and τ d = 14.96 µs at V ds = 0 V. A faster photoresponse with τ r = 6.15 µs and τ d = 4.35 µs is obtained at V ds = −0.20 V. This faster dynamics is assigned to the enhanced electric field of the heterostructure by the applied reverse bias . As summarized in Table 1 , the measured photoresponse times are shorter than those reported for MoTe 2 based FETs and several other heterostructure photodetectors in the literature . We assign the improved photoresponse to the short transport channel and enhanced built‐in electric field of the heterostructure.…”

Section: Resultsmentioning

confidence: 78%

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: Resultsmentioning

confidence: 78%

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Xia

Yan

et al. 2019

Advanced Optical Materials

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“…This 2D semiconductor has a band gap energy that increases markedly with decreasing layer thickness down to a single layer, [ 3–7 ] resulting into a high, broad photoresponsivity that extends from the ultra‐violet (UV) to the infrared (IR) range. [ 8–11 ] Furthermore, the low effective mass of the conduction band (CB) [ 6 ] leads to a high room temperature electron mobility, larger than that in Si‐based field effect transistors. [ 6,12,13 ] These properties make InSe an ideal compromise between semiconducting Si and high‐mobility graphene for 2D digital electronics and optoelectronics.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Optical Emission from 2D InSe Bent onto Si‐Pillars

Mazumder

Xie

Kudrynskyi

et al. 2020

Advanced Optical Materials

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Controlling the propagation and intensity of an optical signal is central to several technologies ranging from quantum communication to signal processing. These require a versatile class of functional materials with tailored electronic and optical properties, and compatibility with different platforms for electronics and optoelectronics. Here, the inherent optical anisotropy and mechanical flexibility of atomically thin semiconducting layers are investigated and exploited to induce a controlled enhancement of optical signals. This enhancement is achieved by straining and bending layers of the van der Waals crystal indium selenide (InSe) onto a periodic array of Si‐pillars. This enhancement has strong dependence on the layer thickness and is modelled by first‐principles electronic band structure theory, revealing the role of the symmetry of the atomic orbitals and light polarization dipole selection rules on the optical properties of the bent layers. The effects described in this paper are qualitatively different from those reported in other materials, such as transition metal dichalcogenides, and do not arise from a photonic cavity effect, as demonstrated before for other semiconductors. The findings on InSe offer a route to flexible nano‐photonics compatible with silicon electronics by exploiting the flexibility and anisotropic and wide spectral optical response of a 2D layered material.

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“…Even with the possible reflection of incident light by the top h‐BN, it turns out that h‐BN encapsulation improves the photodetection. [ 48 ] This is due to the improved InSe mobility and non‐oxidized InSe surface encapsulated by h‐BN. The encapsulation with h‐BN also allows the three‐month air stability, as presented in Figure 2h.…”

Section: Resultsmentioning

confidence: 99%

High‐Performance Near‐Infrared Photodetectors Based on Surface‐Doped InSe

Jang

Seok

Choi

et al. 2020

Adv Funct Materials

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2D InSe is one of the semimetal chalcogenides that has been recently given attention thanks to its excellent electrical properties, such as high mobility near 1000 cm 2 V −1 s −1 and moderate band gap of ≈1.26 eV suitable for IR detection. Here, high-performance visible to near-infrared (470-980 nm wavelength (λ)) photodetectors using surface-doped InSe as a channel and few-layer graphenes (FLG) as electrodes are reported, where the InSe top region is relatively p-doped using AuCl 3. The surface-doped InSe photodetectors show outstanding performance, achieving a photoresponsivity (R) of ≈19 300 A W −1 and a detectivity (D*) of ≈3 × 10 13 Jones at λ = 470 nm, and R of ≈7870 A W −1 and D* of ≈1.5 × 10 13 Jones at λ = 980 nm, superior to previously reported 2D materialbased IR photodetectors operating without an applied gate bias. Surface doping using AuCl 3 renders a band bending at the junction between the InSe surface and the top FLG contact, which facilitates electron-hole pair separation and immediate photodetection. Multiple doped or undoped InSe photodetectors with different device structures are investigated, providing insight into the photodetection mechanism and optimizing performance. Encapsulation with hexagonal boron nitride dielectric also allows for 3-month stability.

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Photoquantum Hall Effect and Light‐Induced Charge Transfer at the Interface of Graphene/InSe Heterostructures

Cited by 23 publications

References 32 publications

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Enhanced Optical Emission from 2D InSe Bent onto Si‐Pillars

High‐Performance Near‐Infrared Photodetectors Based on Surface‐Doped InSe

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Photoquantum Hall Effect and Light‐Induced Charge Transfer at the Interface of Graphene/InSe Heterostructures

Cited by 23 publications

References 32 publications

Enhanced Photoresponse in MoTe2 Photodetectors with Asymmetric Graphene Contacts

Enhanced Photoresponse in MoTe2 Photodetectors with Asymmetric Graphene Contacts

Enhanced Optical Emission from 2D InSe Bent onto Si‐Pillars

High‐Performance Near‐Infrared Photodetectors Based on Surface‐Doped InSe

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Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts

Enhanced Photoresponse in MoTe₂ Photodetectors with Asymmetric Graphene Contacts