- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Selective Transfer of Rotationally Commensurate MoS <sub/>2</sub> from an Epitaxially Grown van der Waals Heterostructure
摘要： Large-scale synthesis of high quality two-dimensional (2D) semiconductors are critical for their incorporation in emerging electronic and optoelectronic technologies. In particular, chemical vapor deposition (CVD) of transition metal dichalcogenides (TMDs) via van der Waals epitaxy on epitaxial graphene (EG) leads to rotationally commensurate TMDs in contrast to randomly aligned TMDs grown on amorphous oxide substrates. However, the interlayer coupling between TMDs and EG hinders the investigation and utilization of the intrinsic electronic properties of the resulting TMDs, thus requiring their isolation from the EG growth substrate. To address this issue, we report here a technique for selectively transferring monolayer molybdenum disulfide (MoS2) from CVD-grown MoS2-EG van der Waals heterojunctions using copper (Cu) adhesion layers. The choice of Cu as the adhesion layer is motivated by density functional theory calculations that predict the preferential binding of monolayer MoS2 to Cu in contrast to graphene. Atomic force microscopy and optical spectroscopy confirm the large-scale transfer of rotationally commensurate MoS2 onto SiO2/Si substrates without cracks, wrinkles, or residues. Furthermore, the transferred MoS2 shows high performance in field-effect transistors with mobilities up to 30 cm2/Vs and on/off ratios up to 106 at room temperature. This transfer technique can likely be generalized to other TMDs and related 2D materials grown on EG, thus offering a broad range of benefits in nanoelectronic, optoelectronic, and photonic applications.
关键词： molybdenum disulfide,van der Waals epitaxy,two-dimensional semiconductors,field-effect transistors,copper adhesion layers,transition metal dichalcogenides,chemical vapor deposition
更新于2025-09-23 15:21:21
-
[NanoScience and Technology] Silicene (Prediction, Synthesis, Application) || Electronic and Topological Properties of Silicene, Germanene and Stanene
摘要： In this chapter, we review the recent progress on electronic and topological properties of monolayer topological insulators including silicene, germanene and stanene. We start with the description of the topological nature of the general Dirac system and then apply it to silicene by introducing the spin and valley degrees of freedom. Based on them, we classify all topological insulators in the general honeycomb system. We discuss topological electronics based on honeycomb systems. We introduce the topological Kirchhoff law, which is a conservation law of topological edge states. Field effect topological transistor is proposed based on the topological edge states. We show that the conductance is quantized even in the presence of random distributed impurities. Monolayer topological insulators will be a key for future topological electronics and spin-valleytronics.
关键词： topological Kirchhoff law,silicene,topological insulators,topological electronics,Dirac system,field effect topological transistor,spin and valley degrees of freedom,stanene,quantized conductance,germanene
更新于2025-09-23 15:21:21
-
Recent Advances in Black Phosphorus-Based Electronic Devices
摘要： The rediscovery of graphene in the recent past has propelled the rapid development of exfoliation and other thin layer processing techniques, leading to a renewed interest in black phosphorus (BP). Since 2014, BP has been extensively studied due to its superior electronic, photonic, and mechanical properties. In addition, the unique intrinsic anisotropic characteristics resulting from its puckered structure can be utilized for designing new functional devices. In retrospect, significant efforts have been directed toward the synthesis, basic understanding, and applications of BP in the fields of nanoelectronics, ultrafast optics, nanophotonics, and optoelectronics. Here, the recent development of BP-based devices, such as nanoribbon field-effect transistors, complementary logic circuits, memory devices, and the progress made in meeting the challenges associated with contact resistance, in-plane anisotropy, and advanced gate stack, are reviewed. Finally, the prospects of 2D materials in meeting the International Technology Roadmap for Semiconductor requirements for the year 2030 are discussed.
关键词： black phosphorus,memory,gas sensors,field-effect transistors,complementary logic circuits
更新于2025-09-23 15:21:21
-
Conjugated Polymers Based on Thiazole Flanked Naphthalene Diimide for Unipolar n-Type Organic Field-Effect Transistors
摘要： This paper reports the rational design and synthesis of a novel electron-withdrawing building block, thiazole flanked naphthalene diimide (TzNDI), which offers a coplanar conformation and deep-lying highest occupied molecular orbitals energy level in resulting conjugated polymers. A series of conjugated polymers (PTzNDI-2FT, PTzNDI-T, PTzNDI-Se, and PTzNDI-2T) consisting of TzNDI and different donor units were synthesized and characterized. The polymers all possess a high molecular weight and excellent thermal property. Their intense light absorption in low energy bands suggests an enhanced intramolecular charge transfer. The organic field-effect transistors (OFETs) based on these polymers exhibit unipolar n-type transport characteristics with low off current and high on–off current ratio. More importantly, all the devices exhibit near ideal transfer curves with kink-free transfer characteristics. Among these polymers, PTzNDI-2FT exhibits the highest electron mobility (μe) of 0.57 cm2 V?1 s?1, outperforming the commercial n-type polymer N2200 (0.41 cm2 V?1 s?1) under the same conditions. These results demonstrate that TzNDI is a promising building block for high performance unipolar n-type conjugated polymers in OFETs.
关键词： Unipolar n-Type,Thiazole Flanked Naphthalene Diimide,Conjugated Polymers,Organic Field-Effect Transistors
更新于2025-09-23 15:21:21
-
Van der Waals junction field effect transistors with both n- and p-channel transition metal dichalcogenides
摘要： Two-dimensional (2D) transition metal dichalcogenides (TMDs)-based van der Waals (vdW) PN junctions have been used for heterojunction diodes, which basically utilize out-of-plane current across the junction interface. In fact, the same vdW PN junction structure can be utilized for another important device application, junction field effect transistors (JFETs), where in-plane current is possible along with 2D–2D heterojunction interface. Moreover, the 2D TMD-based JFET can use both p- and n-channel for low voltage operation, which might be its unique feature. Here we report vdW JFETs as an in-plane current device with heterojunction between semiconducting p- and n-TMDs. Since this vdW JFET would have low-density traps at the vdW interface unlike 2D TMD-based metal insulator semiconductor field effect transistors (MISFETs), little hysteresis of 0.0–0.1 V and best subthreshold swing of ~100 mV/dec were achieved. Easy saturation was observed either from n-channel or p-channel JFET as another advantage over 2D MISFETs, exhibiting early pinch-off at ~1 V. Operational gate voltage for threshold was near 0 V and our highest mobility reaches to ~>500 cm2/V·s for n-channel JFET with MoS2 channel. For 1 V JFET operation, our best ON/OFF current ratio was observed to be ~104.
关键词： n-channel,field effect transistors,van der Waals junction,transition metal dichalcogenides,p-channel
更新于2025-09-23 15:21:21
-
[IEEE 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Brasov, Romania (2019.11.3-2019.11.6)] 2019 8th International Conference on Renewable Energy Research and Applications (ICRERA) - Stable Operation of an Automotive Photovoltaic System under Moving Shadows
摘要： This paper presents a simple mathematical expression to model the effect of statistical dopant fluctuations on threshold voltage (Vth) of junction field-effect transistors (JFETs). The random discrete doping (RDD) in the active device area is used to derive an analytical model to compute the standard deviation, σ Vth,RDD of the Vth-distribution for any arbitrary channel doping profiles. The model shows that the Vth-variability in JFETs depends on the active device area, channel doping concentration, and the depth of the channel depletion region of the gate/channel pn-junction. The model is applied to compute σ Vth,RDD for symmetric and asymmetric source/drain double-gate n-channel JFETs. The simulation results show that the model can be used for predicting Vth-variability in JFETs.
关键词： statistical dopant fluctuations,random discrete doping,process variability in JFETs,modeling threshold voltage variability,JFET threshold voltage variability,Junction field-effect transistor (JFET)
更新于2025-09-23 15:21:01
-
One-step growth of centimeter-scale doped multilayer MoS <sub/>2</sub> films by pulsed laser-induced synthesis
摘要： Recently, two-dimensional MoS2 has attracted interest for applications in electronics, optics, energy storage, and catalysis. Furthermore, n-type or p-type doping of MoS2 can result in improved film properties, thereby expanding the range of applicability. However, the rapid preparation of large-scale MoS2 films and the e?ective doping of such films remain challenging. Herein, we report on a one-step growth method called pulsed laser-induced synthesis (PLIS) that can resolve these challenges and can quickly (5–10 min) prepare centimeter-scale MoS2 films directly and selectively on a substrate. A continuous length of up to 1.412 cm can be achieved with MoS2 films prepared by the described in situ doping of noble metals (Au, Pt, and Pd) to convert MoS2 into a p-type semiconductor was realized, consistent with the results obtained from first-principles calculations. The STEM images reveal that the phenomena of surface modification and cation substitution occur in the doped MoS2 films. The doped MoS2 films were further processed into a p-type field effect transistor with an on/off ratio of 105. Importantly, this technique can be applied to other transition metal dichalcogenides (TMDCs) while employing various doping elements; this scheme provides an innovative method for upscaling production and large-area doping of TMDC thin films.
关键词： TMDCs,MoS2,field effect transistor,doping,pulsed laser-induced synthesis
更新于2025-09-23 15:21:01
-
Controlled doping of graphene by impurity charge compensation via a polarized ferroelectric polymer
摘要： A simple technique of doping graphene by manipulating adsorbed impurity charges is presented. Using a field effect transistor configuration, controlled polarization of a ferroelectric polymer gate is used to compensate and neutralize charges of one type. The uncompensated charges of the opposite type then dope graphene. Both n- and p-type doping are possible by this method, which is non-destructive and reversible. We observe a change in n-type dopant concentration of 8 × 1012 cm?2 and a change in electron mobility of 650%. The electron and hole mobilities are inversely proportional to the impurity concentration, as predicted by theory. Selective doping of graphene can be achieved using this method by patterning gate electrodes at strategic locations and programming them independently. Such charge control without introducing hard junctions, therefore, permits seamless integration of multiple devices on a continuous graphene film.
关键词： ferroelectric polymer,doping,graphene,charge compensation,field effect transistor
更新于2025-09-23 15:21:01
-
[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Understanding the Sidewall Dependence of Loss for Ge-on-Si Waveguides in the Mid-Infrared
摘要： An empirical model for field-effect transistor (FET) based power detectors is presented. The electrical model constitutes a Volterra analysis based on a Taylor series expansion of the drain current together with a linear embedding small-signal circuit. It is fully extracted from S-parameters and IV curves. The final result are closed-form expressions for the frequency dependence of the noise equivalent power (NEP) in terms of the FET intrinsic capacitances and parasitic resistances. Excellent model agreement to measured NEP of coplanar access graphene FETs with varying channel dimensions up to 67 GHz is obtained. The influence of gate length on responsivity and NEP is theoretically and experimentally studied.
关键词： field-effect transistors (FETs),Volterra,terahertz detectors,microwave detectors,graphene,power detectors,Analytical model
更新于2025-09-23 15:21:01
-
Transconductance Amplification in Dirac-Source Field-Effect Transistors Enabled by Graphene/Nanotube Hereojunctions
摘要： Steep-slope devices are predicted to provide excellent quality for analog integrated circuit applications due to their high transconductance efficiency (gm/Ids) breaking the metal-oxide-semiconductor field-effect transistor limit (38.5 V?1). The potential advantage of a Dirac-source FET (DSFET) as an analog transistor is explored based on a graphene/carbon nanotube (CNT) heterojunction. A high gm/Ids beyond 38.5 V?1 over four decades of current is experimentally demonstrated in an individual CNT-based DSFET, reaching a peak value of 66 V?1, which is a new record for all reported transistors. Importantly, this high gm/Ids extends beyond the subthreshold region and leads to transconductance amplification in the overthreshold region. The best peak transconductance at a low bias of ?0.1 V exceeds 20 μS per tube, which has approximately threefold improvement over that of a normal CNT FET with a shorter gate length. Outperforming other advanced devices, the extended high transconductance efficiency greatly promotes DSFET competitiveness in the high-precision analog field.
关键词： carbon nanotubes,heterojunctions,Dirac sources,graphene,field-effect transistors
更新于2025-09-23 15:21:01