RESUMEN
Two-dimensional (2D) semiconductors have shown great potential for monolithic three-dimensional (M3D) integration due to their dangling-bonds-free surface and the ability to integrate to various substrates without the conventional constraint of lattice matching1-10. However, with atomically thin body thickness, 2D semiconductors are not compatible with various high-energy processes in microelectronics11-13, where the M3D integration of multiple 2D circuit tiers is challenging. Here we report an alternative low-temperature M3D integration approach by van der Waals (vdW) lamination of entire prefabricated circuit tiers, where the processing temperature is controlled to 120 °C. By further repeating the vdW lamination process tier by tier, an M3D integrated system is achieved with 10 circuit tiers in the vertical direction, overcoming previous thermal budget limitations. Detailed electrical characterization demonstrates the bottom 2D transistor is not impacted after repetitively laminating vdW circuit tiers on top. Furthermore, by vertically connecting devices within different tiers through vdW inter-tier vias, various logic and heterogeneous structures are realized with desired system functions. Our demonstration provides a low-temperature route towards fabricating M3D circuits with increased numbers of tiers.
RESUMEN
Creating high-quality contacts between high-melting-point metals and delicate two-dimensional (2D) semiconductors poses a critical challenge to polarity control due to inevitable chemical disorder and Fermi-level pinning observed in the contact regions. Here, we report a van der Waals (vdW) integration strategy to precisely tailor the WSe2 polarity by meticulously modulating metal contact compositions. Controlling the low-melting-point bismuth (Bi) thickness effectively modulates the Bi/Au dominant contact with WSe2. This facilitates the precise polarity transformation between n-type, ambipolar, and p-type, with exceptional field-effect mobilities of 200 cm2 V-1 s-1 for electrons and 136 cm2 V-1 s-1 for holes. Within this vdW geometry, we further demonstrate the fundamental electrical components such as diodes and complementary inverters with enhanced rectification ratios and voltage gains. Our results showcase an effective and compatible with mass manufacturing method for precise polarity modulation of 2D semiconductors, providing a promising pathway toward large-scale high-performance 2D electronics and integrated circuits.
RESUMEN
van der Waals heterostructures (vdWHs) based on two-dimensional (2D) semiconductors have attracted considerable attention. However, the reported vdWHs are largely based on vertical device structure with large overlapping area, while the realization of lateral heterostructures contacted through 2D edges remains challenging and is majorly limited by the difficulties of manipulating the lateral distance of 2D materials at nanometer scale (during transfer process). Here, we demonstrate a simple interfacial sliding approach for realizing an edge-by-edge lateral contact. By stretching a vertical vdWH, two 2D flakes could gradually slide apart or toward each other. Therefore, by applying proper strain, the initial vertical vdWH could be converted into a lateral heterojunction with intimately contacted 2D edges. The lateral contact structure is supported by both microscope characterization and in situ electrical measurements, exhibiting carrier tunneling behavior. Finally, this approach can be extended to 3D thin films, as demonstrated by the lateral 2D/3D and 3D/3D Schottky junction.
RESUMEN
BACKGROUND AND AIMS: Diabetic kidney disease (DKD) is one of the most common complications of diabetes. It is reported that mesenchymal stem cells (MSCs) derived exosomes (MSCs-Exo) may have great clinical application potential for the treatment of DKD, but the underlying mechanism has not been illustrated. To clarify the effect of MSC-Exo on NOD2 signaling pathway in podocytes under high glucose (HG) and DKD, we conduct this study. METHODS: We co-cultured podocytes and MSCs-Exo under 30 mM HG and injected MSCs-Exo into DKD mice, then we detected the NOD2 signaling pathway by western blot, qRT-PCT, immunofluorescence, transmission electron microscopy and immunohistochemistry both in vitro and in vivo. RESULTS: In vitro, HG lead to the apoptosis, increased the ROS level and activated the NOD2 signaling pathway in podocytes, while MSCs-Exo protected podocytes from injury reduced the expression of inflammatory factors including TNF-α, IL-6, IL-1ß, and IL-18 and alleviated the inflammatory response, inhibited the activation of NOD2 signaling pathway and the expression of it's downstream protein p-P65, p-RIP2, prevented apoptosis, increased cell viability in podocytes caused by HG. In vivo, MSCs-Exo alleviated renal injury in DKD mice, protected renal function, decreased urinary albumin excretion and inhibited the activation of NOD2 signaling pathway as well as the inflammation in renal tissue. CONCLUSION: MSCs-Exo protected the podocytes and DKD mice from inflammation by mediating NOD2 pathway, MSCs-Exo may provide a new target for the treatment of DKD.
Asunto(s)
Apoptosis , Nefropatías Diabéticas , Exosomas , Células Madre Mesenquimatosas , Proteína Adaptadora de Señalización NOD2 , Podocitos , Transducción de Señal , Animales , Exosomas/metabolismo , Nefropatías Diabéticas/metabolismo , Nefropatías Diabéticas/terapia , Células Madre Mesenquimatosas/metabolismo , Ratones , Proteína Adaptadora de Señalización NOD2/metabolismo , Podocitos/metabolismo , Podocitos/patología , Masculino , Ratones Endogámicos C57BL , Glucosa/metabolismo , Proteína Serina-Treonina Quinasa 2 de Interacción con Receptor/metabolismo , Técnicas de Cocultivo , Trasplante de Células Madre Mesenquimatosas/métodos , Especies Reactivas de Oxígeno/metabolismo , Riñón/patología , Riñón/metabolismo , Diabetes Mellitus Experimental/complicacionesRESUMEN
Vertical transistors hold promise for the development of ultrascaled transistors. However, their on/off ratios are limited by a strong source-drain tunneling current in the off state, particularly for vertical devices with a sub-5 nm channel length. Here, we report an approach for suppressing the off-state tunneling current by designing the barrier height via a van der Waals metal contact. Via lamination of the Pt electrode on a MoS2 vertical transistor, a high Schottky barrier is observed due to their large work function difference, thus suppressing direct tunneling currents. Meanwhile, this "low-energy" lamination process ensures an optimized metal/MoS2 interface with minimized interface states and defects. Together, the highest on/off ratios of 5 × 105 and 104 are realized in vertical transistors with 5 and 2 nm channel lengths, respectively. Our work not only pushes the on/off ratio limit of vertical transistors but also provides a general rule for reducing short-channel effects in ultrascaled devices.
RESUMEN
2D Semiconductors are promising in the development of next-generation photodetectors. However, the performances of 2D photodetectors are largely limited by their poor light absorption (due to ultrathin thickness) and small detection range (due to large bandgap). To overcome the limitations, a strain-plasmonic coupled 2D photodetector is designed by mechanically integrating monolayer MoS2 on top of prefabricated Au nanoparticle arrays. Within this structure, the large biaxial tensile strain can greatly reduce the MoS2 bandgap for broadband photodetection, and at the same time, the nanoparticles can significantly enhance the light intensity around MoS2 with much improved light absorption. Together, the strain-plasmonic coupled photodetector can broaden the detection range by 60 nm and increase the signal-to-noise ratio by 650%, representing the ultimate optimization of detection range and detection intensity at the same time. The strain-plasmonic coupling effect is further systematically characterized and confirmed by using Raman and photoluminescence spectrophotometry. Furthermore, the existence of built-in potential and photo-switching behavior is demonstrated between the strained and unstrained region, constructing a self-powered homojunction photodetector. This approach provides a simple strategy to couple strain effect and plasmonic effect, which can provide a new strategy for designing high-performance and broadband 2D optoelectronic devices.
RESUMEN
AIM: The purpose of this study was to summary the characteristics of ophthalmic artery (OphA) aneurysms and to obtain the independent risk factors for poor prognosis of microsurgical clipping treatment for OphA aneurysms. METHODS: The clinical and microsurgical clipping results of all 63 patients with ophthalmic aneurysm were investigated and reviewed. The OphA aneurysm patient's case records were reviewed including clinical characteristics, image findings, and clinical outcomes. Then, the risk factors of poor prognosis were analyzed retrospectively. RESULTS: Monocular blindness persisted in 4 patients (6.35%), 1 patient developed persistent vegetate state (PVS) (1.59%), while 4 patients (6.35%) died. The matching process constructed a cohort consisting of 9 poor outcome (Glasgow Outcome Scale, GOS 1-3) patients (14.3%), and 54 good outcome (GOS 4-5) patients (85.7%). Univariate analysis between the good outcome and poor outcome revealed statistical significance in age > 60 (p = 0.045), size (p = 0.016), and rupture before operation (p = 0.049). Further, multivariate logistic regression analysis identified age > 60 (odds ratio [OR], 5.877; 95% confidence interval [CI], 1.039-33.254; p = 0.045) and aneurysm size > 10mm (OR, 9.417; 95% CI, 1.476-60.072; p = 0.018) as the independent risk factors for poor outcome in microsurgical clipping treatment for OphA aneurysms. CONCLUSION: The significant independent risk factors associated with clipping OphA aneurysms are age (>60) and size (>10mm).
Asunto(s)
Aneurisma Roto , Aneurisma Intracraneal , Aneurisma Roto/cirugía , Humanos , Aneurisma Intracraneal/cirugía , Microcirugia , Arteria Oftálmica/diagnóstico por imagen , Arteria Oftálmica/cirugía , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
BACKGROUND Levetiracetam (LEV) is an antiepileptic drug that promotes recovery of neurological function by alleviating inflammatory reactions. However, it is not known whether it can improve secondary brain injury after intracerebral hemorrhage (ICH). The aim of this study was to determine whether LEV can reduce early inflammatory response after ICH in rats. MATERIAL AND METHODS An in vitro model of early inflammation was created by treating microglia cells with lipopolysaccharide (LPS). After exposure to various concentrations of LEV, the expression levels of NF-kappaB and STAT3 and inflammatory factors such as interleukin (IL)-1ß and tumor necrosis factor (TNF)-alpha in microglia were detected. In vivo, autologous blood was used to induce the rat ICH model. The effects of LEV on post-cerebral hemorrhagic inflammatory response were examined using neurobehavioral tests, FJC staining, brain water content testing, and analysis of protein expression levels of NF-kappaB, JAK2, STAT3, and inflammatory factors. RESULTS LEV treatment significantly reduced the expression of inflammatory factors and protein expression levels of NF-kappaB and STAT3 in LPS-treated microglia cells (P<0.05). In male Sprague-Dawley (SD) rats, LEV treatment markedly decreased the volume of hematoma and the number of degenerative neurons (P<0.05). It also improved the neurological function and relieved brain edema. The protein expression levels of NF-kappaB, JAK2, and STAT3 were significantly lower in the ICH+LEV group than in the control group (P<0.05). CONCLUSIONS Our study suggests that treatment with LEV alleviates early inflammatory responses induced by ICH. Mechanistically, LEV inhibited the JAK2-STAT3 signaling pathway and reduced neuronal injury around the hematoma, and ameliorated brain edema, all of which promoted recovery of nerve function after hemorrhage.
Asunto(s)
Hemorragia Cerebral/patología , Levetiracetam/farmacología , Fármacos Neuroprotectores/farmacología , Transducción de Señal/efectos de los fármacos , Animales , Hemorragia Cerebral/metabolismo , Inflamación/metabolismo , Inflamación/patología , Janus Quinasa 2/efectos de los fármacos , Janus Quinasa 2/metabolismo , Masculino , Ratas , Ratas Sprague-Dawley , Factor de Transcripción STAT3/efectos de los fármacos , Factor de Transcripción STAT3/metabolismoRESUMEN
BACKGROUND Rupture of intracranial aneurysms (IA) is associated with high rates of mortality around the world. Use of intestinal probiotics can regulate the pathophysiology of aneurysms, but the details of the mechanism involved have been unclear. MATERIAL AND METHODS The GEO2R analysis website was used to detect the DEGs between IAs, AAAs, samples after supplementation with probiotics, and normal samples. The online tool DAVID provides functional classification and annotation analyses of associated genes, including GO and KEGG pathway. PPI of these DEGs was analyzed based on the STRING database, followed by analysis using Cytoscape software. RESULTS We found 170 intersecting DEGs (contained in GSE75240 and more than 2 of the 4 aneurysms datasets), 5 intersecting DEGs (contained in all datasets) and 1 intersecting DEG (contained in GSE75240 and all IAs datasets). GO analysis results suggested that the DEGs primarily participate in signal transduction, cell adhesion, immune response, response to drug, extracellular matrix organization, cell-cell signaling, and inflammatory response in the BP terms, and the KEGG pathways are mainly enriched in focal adhesion, cytokine-cytokine receptor interaction, ECM-receptor interaction, amoebiasis, chemokine signaling pathway, proteoglycans, and PI3K-Akt signaling pathway in cancer pathways. Through PPI network analysis, we confirmed 2 candidates for further study: CAV1 and MYH11. These downregulated DEGs are associated with the formation of aneurysms, and the change of these DEGs is the opposite in probiotics-treated animals. CONCLUSIONS Our study suggests that MYH11 and CAV1 are potential target genes for prevention of aneurysms. Further experiments are needed to verify these findings.
Asunto(s)
Biología Computacional , Aneurisma Intracraneal/genética , Probióticos , Caveolina 1/genética , Regulación hacia Abajo , Regulación de la Expresión Génica , Ontología de Genes , Humanos , Cadenas Pesadas de Miosina/genética , Programas InformáticosRESUMEN
OBJECT: Intracranial mirror aneurysm is a type of multiple aneurysms, which is rare in clinical and literature. There is no unified conclusion on the treatment strategy of mirror aneurysms. Therefore, our study evaluated the surgical approach and prognosis of a series of mirror aneurysms, and explored the clinical features and treatment strategies of mirror aneurysms. METHODS: This study retrospectively analyzed the clinical features, imaging data, treatment methods and post-hospital results of 67 cases of mirror aneurysms admitted to our department from December 1997 to April 2018. RESULTS: There were 20 males and 47 females with an average age of 53.6 years. Mirror aneurysms are mainly located in the posterior communicating artery and middle cerebral artery. Of 67 patients, 1-stage unilateral craniotomy with bilateral aneurysms in 18 cases, 1-stage bilateral craniotomy with bilateral aneurysms in 17 cases, staged treatment of bilateral aneurysms in 13 cases, and 19 cases only treated the responsible aneurysms. 57 cases with good recovery; 7 cases were self-care; 1 case was heavy disability; 2 cases were dead. In parallel, 8 cases had different degrees of cerebral infarction, 3 cases of hydrocephalus, 3 cases of oculomotor nerve injury, 2 cases died of cerebral hernia resulted from intracranial hypertension, and the remaining 53 cases were better. CONCLUSIONS: The treatment of the mirror aneurysm should be based on the location, size, shape of the aneurysm, the patient's clinical manifestations and the surgeon's experience to choose a personalized treatment.
Asunto(s)
Aneurisma Intracraneal/cirugía , Anciano , Craneotomía , Femenino , Humanos , Hipertensión Intracraneal/cirugía , Masculino , Persona de Mediana Edad , Arteria Cerebral Media/cirugía , Estudios Retrospectivos , Cirujanos , Resultado del TratamientoRESUMEN
Vertical transistors, in which the source and drain are aligned vertically and the current flow is normal to the wafer surface, have attracted considerable attention recently. However, the realization of high-density vertical transistors is challenging, and could be largely attributed to the incompatibility between vertical structures and conventional lateral fabrication processes. Here we report a T-shape lamination approach for realizing high-density vertical sidewall transistors, where lateral transistors could be pre-fabricated on planar substrates first and then laminated onto vertical substrates using T-shape stamps, hence overcoming the incompatibility between planar processes and vertical structures. Based on this technique, we vertically stacked 60 MoS2 transistors within a small vertical footprint, corresponding to a device density over 108 cm-2. Furthermore, we demonstrate two approaches for scalable fabrication of vertical sidewall transistor arrays, including simultaneous lamination onto multiple vertical substrates, as well as on the same vertical substrate using multi-cycle layer-by-layer laminations.
RESUMEN
Two-dimensional (2D) semiconductors have generated considerable attention for high-performance electronics and optoelectronics. However, to date, it is still challenging to mechanically exfoliate large-area and continuous monolayers while retaining their intrinsic properties. Here, we report a simple dry exfoliation approach to produce large-scale and continuous 2D monolayers by using a Ag film as the peeling tape. Importantly, the conducting Ag layer could be converted into AgOx nanoparticles at low annealing temperature, directly decoupling the conducting Ag with the underlayer 2D monolayers without involving any solution or etching process. Electrical characterization of the monolayer MoS2 transistor shows a decent carrier mobility of 42 cm2 V-1 s-1 and on-state current of 142 µA/µm. Finally, a plasmonic enhancement photodetector could be simultaneously realized due to the direct formation of Ag nanoparticles arrays on MoS2 monolayers, without complex approaches for nanoparticle synthesis and integration processes, demonstrating photoresponsivity and detectivity of 6.3 × 105 A/W and 2.3 × 1013 Jones, respectively.
RESUMEN
Two-dimensional (2D) semiconductors hold great promises for ultra-scaled transistors. In particular, the gate length of MoS2 transistor has been scaled to 1 nm and 0.3 nm using single wall carbon nanotube and graphene, respectively. However, simultaneously scaling the channel length of these short-gate transistor is still challenging, and could be largely attributed to the processing difficulties to precisely align source-drain contact with gate electrode. Here, we report a self-alignment process for realizing ultra-scaled 2D transistors. By mechanically folding a graphene/BN/MoS2 heterostructure, source-drain metals could be precisely aligned around the folded edge, and the channel length is only dictated by heterostructure thickness. Together, we could realize sub-1 nm gate length and sub-50 nm channel length for vertical MoS2 transistor simultaneously. The self-aligned device exhibits on-off ratio over 105 and on-state current of 250 µA/µm at 4 V bias, which is over 40 times higher compared to control sample without self-alignment process.
RESUMEN
OBJECTIVES: The aim of this study is to evaluate the expression of syntaxin 6 (STX6) in epithelial ovarian cancer (EOC) and assess the effects of STX6 on the prognosis of patient. METHODS: Using information from the Kaplan-Meier Plotter database, the effects of STX6 expression on overall survival (OS) and progression-free survival (PFS) in ovarian cancer patients were examined. The clinical information of 147 patients with epithelial ovarian cancer was evaluated, and immunohistochemical staining was used to identify STX6 expression in postoperative tumor specimens, and the affection of STX6 expression on patient prognosis was assessed. In addition, the expression of STX6 in tumor tissue, peritoneal metastases (PM) derived from 13 patients with epithelial ovarian cancer and 6 normal ovarian specimens was detected by PCR and Western blot. In order to investigate how STX6 affects the proliferation of tumor cells, STX6 was also over expressed and knock down in ovarian cancer cell lines. Then colony formation assay was used to explore the effect of STX6 regulating on cell proliferation. RESULTS: Kaplan-Meier Plotter enrollment data analysis revealed that patients with overexpressed STX6 had substantially worse OS and PFS than individuals with low STX6 expression. Retrospective study revealed a significant (P<0.05) correlation between the STX6 expression and tumor classifications, tumor stage, peritoneal carcinomatosis index (PCI), and PFS survival of patients. Western blot and PCR findings for fresh samples showed that STX6 was overexpressed in both primary lesions and PM nodules of OC. SKOV3 cell proliferation was shown to be dramatically reduced by STX6 knockdown and promoted by STX6 overexpression, according to the in vitro experiments. CONCLUSION: STX6 may increase the progression of epithelial OC by encouraging the proliferation of cancer cells, indicating that STX6 was a viable therapeutic target of epithelial OC.
Asunto(s)
Neoplasias Ováricas , Femenino , Humanos , Carcinoma Epitelial de Ovario/patología , Línea Celular Tumoral , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Neoplasias Ováricas/patología , Pronóstico , Proteínas Qa-SNARE/genética , Proteínas Qa-SNARE/metabolismo , Estudios RetrospectivosRESUMEN
Alzheimer's disease (AD) is the most common type of dementia characterized by abnormal accumulation of amyloid-ß (Aß) plaques, neuroinflammation, and neuronal loss. Dimethyl itaconate (DI), a membrane-permeable derivative of itaconate, has been recently reported to limit inflammation. However, the effect of DI in the APPswe/PS1ΔE9 (APP/PS1) transgenic mouse model of AD remains unclear. We treated APP/PS1 mice with DI or saline. Our results showed that DI ameliorated the cognitive deficits of APP/PS1 mice. Further, DI significantly decreased brain Aß deposition and Aß levels, inhibited cell apoptosis, decreased hippocampal and cortical neuronal damage. We also found that DI promoted the expression of the Nrf2/HO-1 signaling pathway, while inhibited cognitive impairment, cell apoptosis, and the proinflammatory cytokine levels in the brains of APP/PS1 mice. Our results indicated that DI attenuated memory impairment and neuroinflammation via the Nrf2 signaling pathway in APP/PS1 mice, suggesting that DI might be recognized as a promising candidate for the treatment of AD.
Asunto(s)
Enfermedad de Alzheimer , Disfunción Cognitiva , Ratones , Animales , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/metabolismo , Ratones Transgénicos , Enfermedades Neuroinflamatorias , Factor 2 Relacionado con NF-E2/genética , Péptidos beta-Amiloides/metabolismo , Disfunción Cognitiva/tratamiento farmacológico , Disfunción Cognitiva/etiología , Modelos Animales de Enfermedad , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Presenilina-1/genéticaRESUMEN
Strain engineering has been proposed as a promising method to boost the carrier mobility of two-dimensional (2D) semiconductors. However, state-of-the-art straining approaches are largely based on putting 2D semiconductors on flexible substrates or rough substrate with nanostructures (e.g., nanoparticles, nanorods, ripples), where the observed mobility change is not only dependent on channel strain but could be impacted by the change of dielectric environment as well as rough interface scattering. Therefore, it remains an open question whether the pure lattice strain could improve the carrier mobilities of 2D semiconductors, limiting the achievement of high-performance 2D transistors. Here, we report a strain engineering approach to fabricate highly strained MoS2 transistors on a flat substrate. By mechanically laminating a prefabricated MoS2 transistor onto a custom-designed trench structure on flat substrate, well-controlled strain can be uniformly generated across the 2D channel. In the meantime, the substrate and the back-gate dielectric layer remain flat without any roughness-induced scattering effect or variation of the dielectric environment. Based on this technique, we demonstrate the MoS2 electron mobility could be enhanced by tension strain and decreased by compression strain, consistent with theoretical predictions. The highest mobility enhancement is 152% for monolayer MoS2 and 64% for bilayer MoS2 transistors, comparable to that of a silicon device. Our method not only provides a compatible approach to uniformly strain the layered semiconductors on flat and solid substrate but also demonstrates an effective method to boost the carrier mobilities of 2D transistors.
RESUMEN
Vertical field effect transistors (VFETs) have attracted considerable interest for developing ultra-scaled devices. In particular, individual VFET can be stacked on top of another and does not consume additional chip footprint beyond what is needed for a single device at the bottom, representing another dimension for high-density transistors. However, high-density VFETs with small pitch size are difficult to fabricate and is largely limited by the trade-offs between drain thickness and its conductivity. Here, a simple approach is reported to scale the drain to sub-10 nm. By combining 7 nm thick Au with monolayer graphene, the hybrid drain demonstrates metallic behavior with low sheet resistance of ≈100 Ω sq-1 . By van der Waals laminating the hybrid drain on top of 3 nm thick channel and scaling gate stack, the total VFET pitch size down to 20 nm and demonstrates a higher on-state current of 730 A cm-2 . Furthermore, three individual VFETs together are vertically stacked within a vertical distance of 59 nm, representing the record low pitch size for vertical transistors. The method pushes the scaling limit and pitch size limit of VFET, opening up a new pathway for high-density vertical transistors and integrated circuits.
RESUMEN
The practical application of two-dimensional (2D) semiconductors for high-performance electronics requires the integration with large-scale and high-quality dielectrics-which however have been challenging to deposit to date, owing to their dangling-bonds-free surface. Here, we report a dry dielectric integration strategy that enables the transfer of wafer-scale and high-κ dielectrics on top of 2D semiconductors. By utilizing an ultra-thin buffer layer, sub-3 nm thin Al2O3 or HfO2 dielectrics could be pre-deposited and then mechanically dry-transferred on top of MoS2 monolayers. The transferred ultra-thin dielectric film could retain wafer-scale flatness and uniformity without any cracks, demonstrating a capacitance up to 2.8 µF/cm2, equivalent oxide thickness down to 1.2 nm, and leakage currents of ~10-7 A/cm2. The fabricated top-gate MoS2 transistors showed intrinsic properties without doping effects, exhibiting on-off ratios of ~107, subthreshold swing down to 68 mV/dec, and lowest interface states of 7.6×109 cm-2 eV-1. We also show that the scalable top-gate arrays can be used to construct functional logic gates. Our study provides a feasible route towards the vdW integration of high-κ dielectric films using an industry-compatible ALD process with well-controlled thickness, uniformity and scalability.
RESUMEN
Van der Waals (vdW) metallic contacts have been demonstrated as a promising approach to reduce the contact resistance and minimize the Fermi level pinning at the interface of two-dimensional (2D) semiconductors. However, only a limited number of metals can be mechanically peeled and laminated to fabricate vdW contacts, and the required manual transfer process is not scalable. Here, we report a wafer-scale and universal vdW metal integration strategy readily applicable to a wide range of metals and semiconductors. By utilizing a thermally decomposable polymer as the buffer layer, different metals were directly deposited without damaging the underlying 2D semiconductor channels. The polymer buffer could be dry-removed through thermal annealing. With this technique, various metals could be vdW integrated as the contact of 2D transistors, including Ag, Al, Ti, Cr, Ni, Cu, Co, Au, Pd. Finally, we demonstrate that this vdW integration strategy can be extended to bulk semiconductors with reduced Fermi level pinning effect.
RESUMEN
Two-dimensional (2D) materials have demonstrated promising potential for flexible electronics, owning to their atomic thin body thickness and dangling-bond-free surface. Here, we report a sliding contact device structure for efficient strain releasing. By fabricating a weakly coupled metal-2D junction with a van der Waals (vdW) gap in between, the applied strain could be effectively released through their interface sliding; hence minimized strain is transferred to the 2D lattice. Therefore, we observed stable device behavior with electrodes stretching over 110%, much higher than 2D devices using evaporated metal contacts. Furthermore, through multicycle straining-releasing measurements, we found the electrodes still form intimate contact with nearly constant contact resistance during sliding, confirming the optimization of device flexibility and electrical properties at the same time. Finally, we demonstrate this vdW sliding contact is a general device geometry and could be well-extended to various 2D or 3D bulk materials, leading to devices with much higher strain tolerance.