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Significant Performance Improvement of Oxide Thin-Film Transistors by a Self-Assembled Monolayer Treatment
摘要： Despite being a standard process in fabrication of organic thin-film transistors (TFTs) to reduce interface trap density and decrease surface energy, self-assembled monolayer (SAM) treatment of gate dielectrics is rarely used in oxide-semiconductor-based TFTs due to possible damage to the SAM during semiconductor deposition. Here, by studying the dependence of plasma damage to SAM on the deposition conditions of InGaZnO (IGZO) semiconductor thin films, the feasibility of enhancing the performance of oxide TFTs using octadecyl-trichlorosilane (OTS)-treated, ultra-thin AlxOy gate dielectrics is explored. It is discovered that under optimized conditions, the TFTs can be significantly improved, showing a reduction of interface trap density by 50% and an increase of carrier mobility and current on/off ratio by a factor of 2.3 and 76, respectively. The effects on bias stress stability also show substantial improvement after the SAM interface treatment. Finally, such an optimized condition is found to also work for IGZO TFTs gated with OTS-treated HfOx, showing an increase of mobility from 7.8 to 16 cm2 V?1 s?1 compared with the untreated devices. As a result, this simple and yet effective interface treatment method and the resulting devices may have potential applications in future low-cost, low-power electronics.
关键词： interface treatment,octadecyltrichlorosilane,self-assembled monolayers,thin-film transistors,oxide semiconductors
更新于2025-09-23 15:19:57
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Sensitive Detection of Dengue Virus Type 2 E-Proteins Signals Using Self-Assembled Monolayers/Reduced Graphene Oxide-PAMAM Dendrimer Thin Film-SPR Optical Sensor
摘要： In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM?1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.
关键词： optical sensor,E-proteins,SPR sensor,PAMAM dendrimer,reduced graphene oxide,dengue virus,self-assembled monolayer
更新于2025-09-23 15:19:57
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Enhancement of the second harmonic signal of nonlinear crystals by self-assembled gold nanoparticles
摘要： In second harmonic generation (SHG), the energy of two incoming photons, e.g., from a femtosecond laser, can be combined in one outgoing photon of twice the energy, e.g., by means of a nonlinear crystal. The SHG efficiency, however, is limited. In this work, the harvested signal is maximized by composing a hybrid system consisting of a nonlinear crystal with a dense coverage of plasmonic nanostructures separated by narrow gaps. The method of self-assembled diblock-copolymer-based micellar lithography with subsequent electroless deposition is employed to cover the whole surface of a lithium niobate (LiNbO3) crystal. The interaction of plasmonic nanostructures with light leads to a strong electric near-field in the adjacent crystal. This near-field is harnessed to enhance the near-surface SHG signal from the nonlinear crystal. At the plasmon resonance of the gold nanoparticles, a pronounced enhancement of about 60-fold SHG is observed compared to the bare crystal within the confocal volume of a laser spot.
关键词： gold nanoparticles,nonlinear crystal,second harmonic generation,lithium niobate,plasmonic nanostructures,electroless deposition,self-assembled diblock-copolymer-based micellar lithography,LiNbO3,SHG
更新于2025-09-23 15:19:57
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Tuning the Emission Colors of Self-Assembled Quantum Dot Monolayers via One-Step Heat Treatment for Display Applications
摘要： Homogeneously self-assembled colloidal semiconductor quantum dot monolayers (QD-SAMs) over large areas are promising materials for thin film optoelectronic device applications, especially for display. Although tuning of emission colors from QDs is generally achieved during wet chemical synthesis and before monolayer formation, we propose in this study a simple and effective method to adjust emission colors after the formation of QD-SAMs by a simple one-step heat treatment. CdSe-based core/shell or core/double shell structured QDs (CdSe/ZnS, CdSe/CdZnS, and CdSe/CdS/ZnS) covered with an optimal set of hydrophobic ligands can form homogeneous and stable QD-SAMs at the air-water interface. The QD-SAMs are subsequently transferred onto hydrophobized glass substrates by the Langmuir-Schaefer (LS) method and thermally treated in air. We found a blueshift of more than 35 nm for the emission wavelength (red to green) by a thermal treatment at 280 °C for 150 min with CdSe/ZnS QD-SAMs. The color can be adjusted by changing the heating temperature and the treatment time. The wavelength shift is in the order of CdSe/ZnS(4L) > CdSe/ZnS(6L) = (CdSe/CdZnS) > (CdSe/CdS/ZnS). The energy dispersive X-ray (EDX) microanalysis of a single QD reveals that the blueshift is mainly caused by atomic diffusion-induced alloying of core/shell type QDs. The main problem of this method is the decreasing emission intensity caused by oxidation during the heat treatment; however, this problem can be solved by use of a SiO2 protective coating on the QD-SAMs. We believe that this simple technique is useful for manufacturing RGB-colored ultrathin QD-SAM films for QDs displays such as QD film display, QD color-filter display, and QD light emitting diode.
关键词： QD Display,Quantum dots,Color tuning,Self-assembled monolayer,atomic diffusion-induced alloying,Thermal treatment
更新于2025-09-23 15:19:57
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Interfacial Band Engineering of MoS <sub/>2</sub> /Gold Interfaces Using Pyrimidine-Containing Self-Assembled Monolayers: Toward Contact-Resistance-Free Bottom-Contacts
摘要： Bottom-contact architectures with common electrode materials such as gold are crucial for the integration of 2D semiconductors into existing device concepts. The high contact resistance to gold—especially for bottom contacts—is, however, a general problem in 2D semiconductor thin-film transistors. Pyrimidine-containing self-assembled monolayers on gold electrodes are investigated for tuning the electrode work functions in order to minimize that contact resistance. Their frequently ignored asymmetric and bias-dependent nature is recorded by Kelvin probe force microscopy through a direct mapping of the potential drop across the channel during device operation. A reduction of the contact resistances exceeding two orders of magnitude is achieved via a suitable self-assembled monolayer, which vastly improves the overall device performance.
关键词： work-function engineering,MoS2,thin-film transistors,self-assembled monolayers,Schottky barrier
更新于2025-09-23 15:19:57
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Structure and Conformation of a Crystalline P3HT Film Adsorbed on an Alkanethiol Self-Assembled Monolayer Deposited on Gold
摘要： All-atom molecular dynamics simulations are performed to investigate the structural and conformational properties of a regioregular poly(3-hexylthiophene) (P3HT) crystal in the presence of a gold (Au) substrate terminated with an n-alkanethiol self-assembled monolayer (SAM). The employed orientation of the P3HT crystals deposited on the SAM is the edge-on, since this orientation is believed to be the most energetically favorable and stable, also yielding the highest charge carrier mobility in organic thin-film transistors. The unit cell of the overall Au/SAM interfacial layer is obtained through detailed ab initio calculations. Systems with a varying number of P3HT stacks on the Au/SAM substrate are studied with an all-atom force field in order to elucidate the effect of polymer thickness on the structural properties of the system. All final structures are found to be stable and well-equilibrated. Insights into the P3HT crystal structure are provided for the P3HT layers in direct contact with the SAM, but also for those deeper in the polymer film. According to the simulations, the majority of conformational and packing properties of the P3HT film are practically similar to those of the bulk crystalline P3HT material, implying that its structure remains unaffected by the presence of the underlying Au/SAM substrate.
关键词： DFT calculations,semiconducting polymers,molecular dynamics simulations,self-assembled monolayers,P3HT
更新于2025-09-23 15:19:57
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Bulk Electrolysis of Zn-Phthalocyanine Unveils Self assembled Nanospheres via Anion Binding
摘要： Stimuli repsonsive π-conjugated macrocyclic systems has shown significant attention in organic electronics, however, amongst them, porphyrins and phthalocyanines unveiled remarkable growth towards materials and biological applications. Herein, we report bulk electrolysis of Zn-phthalocyanine system (ZnPc-OMe) under potential difference of 1.5 V in chloroform results anion binding mechanism directs the formation of self-assembled nanospheres by diffusion controlled approach. Electrochemical and UV-Vis absorption studies of ZnPc-OMe suggest that anion (Cl-) binding ability towards ‘Zn‘ whilst applied potential leads to the formation of H+[(Cl)ZnPc-OMe]- promote the enhanced current and charge generation. Microscopic analysis revealed that ZnPc-OMe and H+[(Cl)ZnPc-OMe]- exhibit the nanosheets and spheres with an average diameter of 0.5 - 1 μm and 300 – 500 nm, respectively. Powder X- ray diffraction analysis and raman spectra revealed the changes in crystalline phase transitions via ion-dipole and p -p stacking interactions. Thus, these unique features are atypical for phthalocyanine derivative hitherto unknown.
关键词： bulk electrolysis,Zn-phthalocyanine,voltage stimulus,anion binding,self-assembled nanospheres
更新于2025-09-23 15:19:57
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Self-assembled nanorods in YBCO matrix a?? a computational study of their effects on critical current anisotropy
摘要： In order to understand how the doping with self-assembled nanorods of different sizes and concentrations as well as applied magnetic fields affect the critical current anisotropy in YBa2Cu3O7?x (YBCO) thin films close to YBCO c-axis, we present an extensive and systematic computational study done by molecular dynamics simulation. the simulations are also used to understand experimentally measured Jc(θ) curves for BaHfO3, BaZrO3 and BaSnO3 doped YBCO thin films with the help of nanorod parameters obtained from transmission electron microscopy measurements. our simulations reveal that the relation between applied and matching field plays a crucial role in the formation of Jc(θ)-peak around YBCO c-axis (c-peak) due to vortex-vortex interactions. We also find how different concentrations of different size nanorods effect the shape of the c-peak and explain how different features, such as double c-peak structures, arise. In addition to this, we have quantitatively explained that, even in an ideal superconductor, the overdoping of nanorods results in decrease of the critical current. our results can be widely used to understand and predict the critical current anisotropy of YBco thin films to improve and develop new pinscapes for various transport applications.
关键词： critical current anisotropy,molecular dynamics simulation,YBCO,flux pinning,self-assembled nanorods
更新于2025-09-23 15:19:57
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Immobilization of DNA on Quartz Crystal Microbalance Sensor Modified with Self-Assembled Monolayer of Thiol Derivative
摘要： In this study, we investigated the direct detection of DNA, without pretreatment, using a quartz crystal microbalance (QCM) sensor. This sensor is modified by a self-assembled monolayer of a thiol derivative that has an amino group as the terminal functional group. Contact angle values and the attenuated total reflectance Fourier transform infrared (ATR/FT-IR) spectra of the QCM sensors after immersion into an ethanol solution of thiol derivatives clearly showed that self-assembled monolayers of the derivatives were formed on the QCM sensors. Although QCM measurements using unmodified and carboxylic group-modified sensors could not detect DNA-Na salt, the sensor modified with amino groups could detect the DNA. This system can be used for the analysis of the interaction between DNA and DNA-binding proteins.
关键词： DNA,thiol derivative,quartz crystal microbalance,self-assembled monolayer
更新于2025-09-23 15:19:57
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Mechanically Induced Switching of Molecular Layers
摘要： Within the field of switchable surfaces, azobenzenes are an extensively studied group of molecules, known for reversibly changing conformation upon illumination with light of different wavelengths. Relying on the ability of the molecules to change properties and structure as a response to external stimuli, they have been incorporated in various devices, such as molecular switches and motors. In contrast to the well-documented switching by light irradiation, we report the discovery of mechanically triggered switching of self-assembled azobenzene monolayers, resulting in changes of surface wettability, adhesion, and friction. This mechanically induced cis?trans isomerization is triggered either locally and selectively by AFM or macroscopically by particle impact. The process is optically reversible, enabling consecutive switching cycles. Collective switching behavior was also observed, propagating from the original point of impact in a domino-like manner. Finally, local force application facilitated nondestructive and erasable nanopatterning, the cis?trans nanolithography.
关键词： Molecular switch,self-assembled monolayers,mechanical switching,nanolithography,azobenzene
更新于2025-09-19 17:15:36