Interfacial charge-transfer for robust Raman quenching in staggered band aligned n-SnS2/p-rGO heterostructures

Natarajan, Vanasundaram; Ahmad, Mifrah; Sharma, Jitendar Paul; Sathya, A.; Kumar, Praveen; Thangaraj, R.

doi:10.1016/j.apsusc.2021.149356

Cited by 18 publications

(7 citation statements)

References 53 publications

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“…In HS, we noticed an apparent reduction and enhancement in the Raman intensity of the A′ 1 mode of 1L-MoS 2 and the A 1g mode of Bi 2 O 2 Se, respectively (see Table S1, SI), indicating a robust interfacial coupling between the heterolayers in the HS. Raman intensity quenching/enhancement is highly correlated with changes in layer numbers, lattice orientation, type of stacking, defects, doping, stress/strain, temperature, laser source, and the variation of electronic and lattice vibration properties, and it could be related to CT, dipole–dipole coupling, and CT with dipole–dipole coupling . We observe a significant quenching (60%) in the intensity of the A′ 1 Raman mode of 1L-MoS 2 and enhancement (82%) of the A 1g mode in Bi 2 O 2 Se in the HS (Table S1, SI), and it is primarily due to the absorption/reflection of light at the top Bi 2 O 2 Se layer, which causes the lower intensity of light to reach the bottom MoS 2 layer, and as a result, the lower intensity of the A′ 1 mode.…”

Section: Resultsmentioning

confidence: 79%

“…Raman intensity quenching/enhancement is highly correlated with changes in layer numbers, lattice orientation, type of stacking, defects, doping, stress/strain, temperature, laser source, and the variation of electronic and lattice vibration properties, and it could be related to CT, dipole−dipole coupling, and CT with dipole−dipole coupling. 47 We observe a significant quenching (60%) in the intensity of the A′ 1 Raman mode of 1L-MoS 2 and enhancement (82%) of the A 1g mode in Bi 2 O 2 Se in the HS (Table S1, SI), and it is primarily due to the absorption/reflection of light at the top Bi 2 O 2 Se layer, which causes the lower intensity of light to reach the bottom MoS 2 layer, and as a result, the lower intensity of the A′ 1 mode. The multilayer nature of HS possibly has multiple interference effects of backscattering of light, which may partly be responsible for the reduction in the A′ 1 mode intensity.…”

Section: Computational Detailsmentioning

confidence: 99%

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Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi₂O₂Se/MoS₂ Type-II Heterojunction

Hossain

Mawlong

Jena

et al. 2023

ACS Appl. Nano Mater.

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Interlayer charge transfer (CT) based on band alignment plays a vital role in various optoelectronic applications, such as photoluminescence modulation, superior photoconduction, etc. The layer-by-layer integration of atomically thin materials with different band alignments is an efficient approach to witness CT. To study interlayer CT, the stacking of ultrathin van der Waals (vdW) materials has been studied extensively, while the stacking of vdW materials with non-van der Waals (nvdW) materials is least explored. Herein, we present the stacking of an nvdW twodimensional (2D) Bi 2 O 2 Se layer over a vdW 2D MoS 2 (monolayer) and study the interlayer coupling and CT across the 2D interface. Studies through various spectroscopic and microscopic tools and density functional theory calculations reveal that significant interlayer CT occurs across the heterolayers due to the favorable band alignment of type-II across the junction. Interestingly, the CT from the 2D Bi 2 O 2 Se layer to the monolayer MoS 2 results in photoluminescence (PL) quenching in the MoS 2 layer and enhanced photoconduction in the HS. Low-temperature PL studies reveal that the robust interlayer coupling between the heterolayers enhances the CT process. The modified Varshni fit reveals that the electron−phonon coupling constant (Huang−Rhys factor) is higher for trions (1.13) than for neutral excitons (0.66) in the heterostructure. Upon photoexcitation, the trion−phonon coupling is stronger than the neutral exciton−phonon coupling in the heterostructure system. The additional doping caused by photogenerated CT was quantified by solving the coupled rate equations using a four-level model, and the results are fully consistent with the CT estimated from the density functional theory (DFT) calculation. These results are significant for understanding the interaction between vdW and nvdW 2D heterostructures and further exploration of such 2D heterostructures in future optoelectronic applications. KEYWORDS: type-II heterostructure, charge transfer, 2D Bi 2 O 2 Se, monolayer MoS 2 , electron−phonon coupling

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Section: Resultsmentioning

confidence: 79%

Section: Computational Detailsmentioning

confidence: 99%

Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi₂O₂Se/MoS₂ Type-II Heterojunction

Hossain

Mawlong

Jena

et al. 2023

ACS Appl. Nano Mater.

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“…The semiconducting properties of two different 2H-phase TMDs have been revealed by Raman spectroscopy (Figure c). , The characteristic peaks of both materials have been observed in the SnS 2 /thiol-MoTe 2 junction area. Interestingly, the intensity of the SnS 2 A 1g peak in the SnS 2 /thiol-MoTe 2 heterojunction decreased compared to the case of pristine SnS 2 due to either charge transfer or strong dipole–dipole coupling among the layers forming the van der Waals heterojunctions, indicating the existence of a strong interaction between SnS 2 and the underlying thiol-MoTe 2 . , It is important to note that thiol-MoTe 2 and SnS 2 sheets interact in a van der Waals manner without losing their semiconducting properties, as previously observed from 2D van der Waals heterojunctions in the absence of chemical treatment. , Figure d illustrates the 2D cross-section of the interface between SnS 2 and thiol-MoTe 2 , where our primary focuses lie on to explain antiambipolar transfer characteristics of the JFET. Under V DS = −1 V, the operation principle of the JFET can be categorized according to different V GS values: (i) V GS < 0 V, (ii) V GS = 0 V, and (iii) V GS > 0 V. In case (i), SnS 2 electrons are depleted, increasing the total resistance of the heterojunction channel, and accordingly perturbing the charge flow.…”

Section: Resultsmentioning

confidence: 99%

Defect Engineering of MoTe₂ via Thiol Treatment for Type III van der Waals Heterojunction Phototransistor

Jeong,

Han,

Tamayo

et al. 2024

ACS Nano

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Molybdenum ditelluride (MoTe 2 ) nanosheets have displayed intriguing physicochemical properties and opto-electric characteristics as a result of their tunable and small band gap (E g ∼ 1 eV), facilitating concurrent electron and hole transport. Despite the numerous efforts devoted to the development of p-type MoTe 2 field-effect transistors (FETs), the presence of tellurium (Te) point vacancies has caused serious reliability issues. Here, we overcome this major limitation by treating the MoTe 2 surface with thiolated molecules to heal Te vacancies. Comprehensive materials and electrical characterizations provided unambiguous evidence for the efficient chemisorption of butanethiol. Our thiol-treated MoTe 2 FET exhibited a 10-fold increase in hole current and a positive threshold voltage shift of 25 V, indicative of efficient hole carrier doping. We demonstrated that our powerful molecular engineering strategy can be extended to the controlled formation of van der Waals heterostructures by developing an n-SnS 2 /thiol-MoTe 2 junction FET (thiol-JFET). Notably, the thiol-JFET exhibited a significant negative photoresponse with a responsivity of 50 A W −1 and a fast response time of 80 ms based on band-to-band tunneling. More interestingly, the thiol-JFET displayed a gate tunable trimodal photodetection comprising two photoactive modes (positive and negative photoresponse) and one photoinactive mode. These findings underscore the potential of molecular engineering approaches in enhancing the performance and functionality of MoTe 2 -based nanodevices as key components in advanced 2D-based optoelectronics.

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“…One can clearly distinguish robust Raman quenching over the whole interface, which further suggests strong charge transfer for the whole heterostructure interface due to the staggered band alignment. 18,43,44 High-resolution transmission electron microscopy (HRTEM) was further used to verify the crystal structure of the WSe 2 and SnS 2 nanosheets (Figures 1f and 1g). The measured widths of the lattice fringes are 0.28 and 0.318 nm for WSe 2 and SnS 2 , respectively, which are in agreement with reports.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…To further highlight the Raman quenching at the junction area, Raman mappings of the A 1g modes for WSe 2 and SnS 2 are shown in Figures d and e, respectively. One can clearly distinguish robust Raman quenching over the whole interface, which further suggests strong charge transfer for the whole heterostructure interface due to the staggered band alignment. ,, High-resolution transmission electron microscopy (HRTEM) was further used to verify the crystal structure of the WSe 2 and SnS 2 nanosheets (Figures f and g). The measured widths of the lattice fringes are 0.28 and 0.318 nm for WSe 2 and SnS 2 , respectively, which are in agreement with reports. − , Selected-area-electron-diffraction (SAED) images exhibit one set of 6-fold symmetry diffraction spots for both nanosheets, confirming their highly crystalline nature.…”

Section: Resultsmentioning

confidence: 99%

Robust Anti-Ambipolar Behavior and Gate-Tunable Rectifying Effect in van der Waals p–n Junctions

Zhao

et al. 2022

ACS Appl. Electron. Mater.

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Anti-ambipolar behavior has been observed in multilayer two-dimensional semiconductors and many p–n junctions. However, temperatures in the range of tens of kelvin are usually required, and there are gaps in the understanding of the underlying physics, most notably the roles of the space charge region and van der Waals (vdW) heterojunction. Here, we systematically investigate the unique transport and transfer characteristics of vertically stacked vdW contacted p-WSe2/n-SnS2 and p-WSe2/n-MoS2 junctions. Interestingly, robust anti-ambipolar behavior is observed at low and room temperature for both darkened and illuminated conditions. A peak-to-valley current ratio exceeding 104 and on-state gating field ranging from −0.3 × 106 to 0.57 × 106 V/cm are achieved at room temperature in darkness. Moreover, the rectifying effect and the type of majority charge carrier of the WSe2/SnS2 junction can be tuned by an electric gate. Robust Raman quenching over the whole interface induced by strong charge transfer is also observed. Based on an equivalent circuit model, a Poisson and drift-diffusion simulation, and experiments with local illumination, we highlight the role of the van der Waals heterojunction. We show that the observed unique anti-ambipolar behavior is due to the recombination of electrons and holes at the space charge region rather than carrier diffusion in the turned-off metal-oxide-semiconductor field-effect transistor (MOSFET). A larger vdW barrier and interface recombination at the vdW barrier are key to having a strong on/off ratio especially at room temperature. The p–n vdW heterostructure plays the roles of a complementary MOSFET connecting with a heterojunction diode, not only a ternary logic inverter but also a tunable multiple-gain amplifier in wide-range gating fields. The width of the middle logic plateau can reach 45 V in a WSe2/MoS2 junction.

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Interfacial charge-transfer for robust Raman quenching in staggered band aligned n-SnS2/p-rGO heterostructures

Cited by 18 publications

References 53 publications

Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi₂O₂Se/MoS₂ Type-II Heterojunction

Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi₂O₂Se/MoS₂ Type-II Heterojunction

Defect Engineering of MoTe₂ via Thiol Treatment for Type III van der Waals Heterojunction Phototransistor

Robust Anti-Ambipolar Behavior and Gate-Tunable Rectifying Effect in van der Waals p–n Junctions

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Interfacial charge-transfer for robust Raman quenching in staggered band aligned n-SnS2/p-rGO heterostructures

Cited by 18 publications

References 53 publications

Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi2O2Se/MoS2 Type-II Heterojunction

Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi2O2Se/MoS2 Type-II Heterojunction

Defect Engineering of MoTe2 via Thiol Treatment for Type III van der Waals Heterojunction Phototransistor

Robust Anti-Ambipolar Behavior and Gate-Tunable Rectifying Effect in van der Waals p–n Junctions

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Product

Resources

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Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi₂O₂Se/MoS₂ Type-II Heterojunction

Interlayer Charge-Transfer-Induced Photoluminescence Quenching and Enhanced Photoconduction in Two-Dimensional Bi₂O₂Se/MoS₂ Type-II Heterojunction

Defect Engineering of MoTe₂ via Thiol Treatment for Type III van der Waals Heterojunction Phototransistor