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Stability of diamond/Si bonding interface during device fabrication process
摘要： Diamond/Si bonding interface with an entire contact area and high thermal stability is achieved by surface activated bonding method. The fabrication of diamond field-effect transistors (FETs) on the diamond bonded to Si is demonstrated. The FET exhibits clear saturation and pinch-off characteristics. A 5 nm thick SixCx-1 layer was formed at the interface with annealing at 1000 °C. The layer was formed by the inter-diffusion of carbon and Si atoms near the bonding interface, which plays a role of residual stress relaxation between diamond and Si. These results suggest that diamond/Si heterostructures are applicable for combining diamond devices with Si LSI.
关键词： surface activated bonding,diamond/Si bonding,heterostructures,thermal stability,field-effect transistors
更新于2025-09-10 09:29:36
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Polyelectrolyte Dielectrics for Flexible Low-Voltage Organic Thin-Film Transistors in Highly Sensitive Pressure Sensing
摘要： Organic thin-film transistors (OTFTs) can provide an effective platform to develop flexible pressure sensors in wearable electronics due to their good signal amplification function. However, it is particularly difficult to realize OTFT-based pressure sensors with both low-voltage operation and high sensitivity. Here, controllable polyelectrolyte composites based on poly(ethylene glycol) (PEG) and polyacrylic acid (PAA) are developed as a type of high-capacitance dielectrics for flexible OTFTs and ultrasensitive pressure sensors with sub-1 V operation. Flexible OTFTs using the PAA:PEG dielectrics show good universality and greatly enhanced electrical performance under a much smaller operating voltage of ?0.7 V than those with a pristine PAA dielectric. The low-voltage OTFTs also exhibit excellent flexibility and bending stability under various bending radii and long cycles. Flexible OTFT-based pressure sensors with low-voltage operation and superhigh sensitivity are demonstrated by using a suspended semiconductor/dielectric/gate structure in combination with the PAA:PEG dielectric. The sensors deliver a record high sensitivity of 452.7 kPa?1 under a low-voltage of ?0.7 V, and excellent operating stability over 5000 cycles. The OTFT sensors can be built into a wearable sensor array for spatial pressure mapping, which shows a bright potential in flexible electronics such as wearable devices and smart skins.
关键词： composite materials,organic field-effect transistors,flexible electronics,pressure sensors,dielectrics
更新于2025-09-10 09:29:36
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Intrinsic Carrier Transport of Phase-Pure Homologous 2D Organolead Halide Hybrid Perovskite Single Crystals
摘要： This work reveals the intrinsic carrier transport behavior of 2D organolead halide perovskites based on phase-pure homologous (n = 1, 2, and 3) Ruddelsden–Popper perovskite (RPP) (BA)2(MA)n?1PbnI3n+1 single crystals. The 2D perovskite field effect transistors with high-quality exfoliated 2D perovskite bulk crystals are fabricated, and characteristic output and transfer curves are measured from individual single-crystal flakes with various n values under different temperatures. Unipolar n-type transport dominated the electrical properties of all these 2D RPP single crystals. The transport behavior of the 2D organolead halide hybrid perovskites exhibits a strong dependence on the n value and the mobility substantially increases as the ratio of the number of inorganic perovskite slabs per organic spacer increases. By extracting the effect of contact resistances, the corrected mobility values for n = 1, 2, and 3 are 2 × 10?3, 8.3 × 10?2, and 1.25 cm2 V?1 s?1 at 77 K, respectively. Furthermore, by combining temperature-dependent electrical transport and optical measurements, it is found that the origin of the carrier mobility dependence on the phase transition for 2D organolead halide perovskites is very different from that of their 3D counterparts. Our findings offer insight into fundamental carrier transport behavior of 2D organic–inorganic hybrid perovskites based on phase-pure homologous single crystals.
关键词： solution growth,field-effect transistors,photoluminescence,intrinsic charge transport,2D RPP single crystals
更新于2025-09-10 09:29:36
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Suppressing Ambipolar Characteristics of WSe <sub/>2</sub> Field Effect Transistors Using Graphene Oxide
摘要： Monolayer (1L) tungsten diselenide (WSe2) is of interest for next generation ultrathin flexible electronic devices. However, typical WSe2 field effect transistors (FETs) show ambipolar characteristics that are not desirable for complementary field-effect-transistors and circuits. Here, significant suppression of the ambipolar characteristics of a 1L-WSe2 FET is demonstrated by using an electron withdrawing functional group of graphene oxide (GO). The pristine 1L-WSe2 FET shows n-type dominant ambipolar characteristics, whereas the GO coated 1L-WSe2 FET shows unipolar p-type behavior with a huge decrease (1/106) of current level of the n-channel. Also, the current level of the p-channel increases up to ten times that of the pristine 1L-WSe2 FET. These results are applicable for the realization of flexible nanoscale digital logic devices by using transition metal dichalcogenides.
关键词： field-effect-transistors,ambipolar,monolayer WSe2,unipolar,electron-withdrawing group
更新于2025-09-10 09:29:36
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Probing the Electronic Properties of Monolayer MoS <sub/>2</sub> via Interaction with Molecular Hydrogen
摘要： This work presents a detailed experimental investigation of the interaction between molecular hydrogen (H2) and monolayer MoS2 field effect transistors (MoS2 FET), aiming for sensing application. The MoS2 FET exhibits a response to H2 that covers a broad range of concentration (0.1–90%) at a relatively low operating temperature range (300–473 K). Most important, H2 sensors based on MoS2 FETs show desirable properties such as full reversibility and absence of catalytic metal dopants (Pt or Pd). The experimental results indicate that the conductivity of MoS2 monotonically increases as a function of the H2 concentration due to a reversible charge transferring process. It is proposed that such process involves dissociative H2 adsorption driven by interaction with sulfur vacancies in the MoS2 surface (VS). This description is in agreement with related density functional theory studies about H2 adsorption on MoS2. Finally, measurements on partially defect-passivated MoS2 FETs using atomic layer deposited aluminum oxide consist of an experimental indication that the VS plays an important role in the H2 interaction with the MoS2. These findings provide insights for future applications in catalytic process between monolayer MoS2 and H2 and also introduce MoS2 FETs as promising H2 sensors.
关键词： hydrogen gas sensor,gas interaction,hydrogen detection,monolayer MoS2,field effect transistors
更新于2025-09-10 09:29:36
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Ge Complementary Tunneling Field-Effect Transistors Featuring Dopant Segregated NiGe Source/Drain
摘要： Ge complementary tunneling field-effect transistors (TFETs) are fabricated with the NiGe metal source/drain (S/D) structure. The dopant segregation method is employed to form the NiGe/Ge tunneling junctions of sufficiently high Schottky barrier heights. As a result, the Ge p- and n-TFETs exhibit decent electrical properties of large ON-state current and steep sub-threshold slope (?? factor). Especially, ??d of 0.2 ??A/??m is revealed at ??g ? ??th = ??d = ±0.5 V for Ge pTFETs, with the ?? factor of 28 mV/dec at 7 K.
关键词： ON-state current,NiGe metal source/drain,Ge complementary tunneling field-effect transistors,sub-threshold slope,Schottky barrier heights,dopant segregation
更新于2025-09-10 09:29:36
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A Global Parameters Extraction Technique to Model Organic Field Effect Transistors Output Characteristics
摘要： After an impressive improvement observed in organic field effect transistors (OFETs) technology, there is a need to have a comprehensive model, which can predict output characteristics of OFETs to facilitate device-to-system integration in an efficient manner. In this paper, a global technique is developed to extract parameters of various OFETs models by evaluating their output characteristics. By involving respective model’s expression, a simulator has been developed wherein the model variables have been extracted by using particle swarm optimization technique. Relative performance of a model is determined by assessing root mean square errors between the experimental and the modeled characteristics. Swarm optimization showed that the accuracy of a model is dependent upon the device dimensions. Thus, by employing the developed swarm optimization technique on devices of various dimensions, a preferred model is identified, which can be employed by the device modeling software. Swarm optimization showed that models, which are more physics based have a wider applicability than those which involved relatively higher number of fitting variables.
关键词： Modeling,Swarm Optimization,I ? V Characteristics,Organic Field Effect Transistors
更新于2025-09-10 09:29:36
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High-performance black phosphorus field-effect transistors with long-term air-stability
摘要： Two-dimensional layered materials (2DLMs) are of considerable interest for high-performance electronic devices for their unique electronic properties and atomically thin geometry. However, the atomically thin geometry makes their electronic properties highly susceptible to the environment changes. In particular, some 2DLMs (e.g., black phosphorus (BP) and SnSe2) are unstable and could rapidly degrade over time when exposed to ambient conditions. Therefore, the development of proper passivation schemes that can preserve the intrinsic properties and enhance their lifetime represents a key challenge for these atomically thin electronic materials. Herein we introduce a simple, non-disruptive and scalable van der Waals passivation approach by using organic thin films to simultaneously improve the performance and air stability of BP field-effect transistors (FETs). We show that dioctylbenzothienobenzothiophene (C8-BTBT) thin films can be readily deposited on BP via van der Waals epitaxy approach to protect BP against oxidation in ambient conditions over 20 days. Importantly, the non-covalent van der Waals interface between C8-BTBT and BP effectively preserves the intrinsic properties of BP, allowing us to demonstrate high-performance BP FETs with a record-high current density of 920 μA/um, hole drift velocity over 1 ⅹ 107 cm/s, and on/off ratio of 104~107 at room temperature. This approach is generally applicable to other unstable two-dimensional (2D) materials, defining a unique pathway to modulate their electronic properties and realize high-performance devices through hybrid heterojunctions.
关键词： black phosphorus,saturation velocity,saturation current density,two-dimensional materials,passivation,field effect transistors
更新于2025-09-10 09:29:36
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Self-consistent procedure including envelope function normalization for full-zone Schr?dinger-Poisson problems with transmitting boundary conditions
摘要： In the quantum mechanical simulation of exploratory semiconductor devices, continuum methods based on a k·p/envelope function model have the potential to significantly reduce the computational burden compared to prevalent atomistic methods. However, full-zone k·p/envelope function simulation approaches are scarce and existing implementations are not self-consistent with the calculation of the electrostatic potential due to the lack of a stable procedure and a proper normalization of the multi-band envelope functions. Here, we therefore present a self-consistent procedure based on a full-zone spectral k·p/envelope function band structure model. First, we develop a proper normalization for the multi-band envelope functions in the presence of transmitting boundary conditions. This enables the calculation of the free carrier densities. Next, we construct a procedure to obtain self-consistency of the carrier densities with the electrostatic potential. This procedure is stabilized with an adaptive scheme that relies on the solution of Poisson’s equation in the Gummel form, combined with successive underrelaxation. Finally, we apply our procedure to homostructure In0.53Ga0.47As tunnel field-effect transistors (TFETs) and staggered heterostructure GaAs0.5Sb0.5/In0.53Ga0.47As TFETs and show the importance of self-consistency on the device predictions for scaled dimensions.
关键词： electrostatic potential,k·p/envelope function model,semiconductor devices,self-consistent procedure,tunnel field-effect transistors,quantum mechanical simulation
更新于2025-09-10 09:29:36
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Photogating and high gain in ReS <sub/>2</sub> field-effect transistors
摘要： Two-dimensional layered transition metal dichalcogenides have shown much promise due to their remarkable electro-optical properties and potential use as photodetectors. We observed photogating in our few-layered (3–4 layers) ReS2 field-effect transistors (FETs) in which varying the incident optical power shifted the FETs’ threshold voltage. The photogating effect produced a significant gain in the electrical response of the FETs to incident light as measured by the responsivity (R) and external quantum efficiency (EQE). We obtained a maximum R of 45 A/W corresponding to an EQE of ～10 500% in a four-terminal measurement of the photoconductivity in the ON-state. We attribute both the photogating and the observed gain to the influence of charge traps. An estimate of the device gain based on our observations is calculated to be 5 × 104. Published by AIP Publishing.
关键词： photodetectors,high gain,charge traps,ReS2,field-effect transistors,photogating
更新于2025-09-10 09:29:36