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过滤筛选
- 2018
- thin-film transistors
- N2O plasma treatment.
- amorphous InGaZnO
- gate-bias stress
- stability
- Electronic Science and Technology
- Peking University
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Transport models in disordered organic semiconductors and their application to the simulation of thin-film transistors
摘要： Relevant organic thin-film transistor (OTFT) simulation software must account for the main specificities of organic semiconductors (OSC) in term of free carriers’ density of states, transport mechanisms, and injection/collection properties from/to the device contacts. Among the parameters impacting the OTFT performance the carrier mobility is a key parameter. Usual methods to extract the mobility from current-voltage (I-V) measurements lead to obtained only an apparent, or effective, mobility. The value of the apparent mobility is different of the intrinsic channel organic semiconductor mobility. Despite this effective mobility actually determines most of a given device performance, therefore providing a very useful technology benchmark, it does not describe the intrinsic organic semiconductor material transport properties, and may even be misleading in the route to improve the OTFT fabrication process. To obtain a better understanding of the transport properties in OSCs using OTFT electrical characterization, implementing an appropriate physical mobility model in an OTFT I-V simulation software is a good way. The present paper gives a review of the carrier mobility models which can be implemented in OTFT simulation software. The review is restricted to the analytical and semi-analytical physical models taking into account the temperature, the carrier concentration and the electric field dependence of the carrier mobility in disordered OSCs.
关键词： mobility,transport,modeling,organic semiconductors,Organic thin-film transistor (OTFT)
更新于2025-09-23 15:22:29
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Subsurface modification induced on ion-exchanged glass substrates by deposition and bombardment
摘要： Ion-exchanged glasses are widely used in optoelectronic devices due to its high strength and optical waveguide effects. The MgF2 films deposited on the ion-exchanged glasses and the ion-exchanged glasses bombarded by argon ions (100 eV) at 220 °C were investigated in the present work. The microstructure of MgF2 films and the structural and physico-chemical properties of the ion-exchanged glasses before and after deposition and bombardment were analyzed by grazing incident X-ray diffraction (GIXRD), field emission scanning electron microscopy (FE-SEM), electron probe micro analysis (EPMA), micro-Raman spectroscopy and surface stress meter. It is shown that MgF2 films exhibit a polycrystalline and microcolumnar structure. The peak of potassium ions concentration distribution in the ion-exchanged glasses, accompanied by outward diffusion of potassium ions, decreases and moves from glass surface to the inner part to different degrees during deposition and bombardment. The potassium ions concentration in the region near the surface of argon ion-bombarded glasses is almost the same as the MgF2-coated glasses. Furthermore, the position and intensity of Raman bands in the subsurface region of the ion-exchanged glasses show obvious changes before and after deposition and bombardment. The values of compressive stress and depth of layer in the MgF2-coated ion-exchanged glasses and the argon ion-bombarded ion-exchanged glasses are far away lower than that of its values obtained in the ion-exchanged glasses. Overall results have shown that variations of chemical composition, Raman bands and surface compressive stress in the exchanged region indicate subsurface modification of the ion-exchanged glasses induced by deposition and bombardment, which provide useful information for the use of the ion-exchanged glasses in further.
关键词： Modification,Ion bombardment,Raman spectroscopy,Ion-exchanged glass,MgF2 thin film
更新于2025-09-23 15:22:29
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Thickness dependence of structural, morphological and optical properties of Mn-Co-Ni-O thin films grown by chemical solution deposition on SiO2/Si(100) substrate
摘要： Mn1.56Co0.96Ni0.48O4 (MCNO) thin film with different thicknesses ranging from 180 nm to 600 nm were deposited onto a SiO2/Si(100) substrate at 600 °C by using the chemical solution deposition method. The thickness dependent structural and optical properties of the MCNO films were investigated in this study. As identified by the SEM pictures and X-ray diffraction (XRD) spectra, all samples showed polycrystalline cubic spinel structure, and the stoichiometric status is improved with growing thickness according to XRD results. Spectroscopic ellipsometry spectra were measured in this study to investigate the thickness dependent optical properties of MCNO film in the range of 300-1000 nm. The samples showed three absorption structures locating at 1.6-1.9 eV, 2.6 eV, and above 3.5 eV, corresponding to the charge transfer transition involving 2p orbitals of O2- and 3d orbitals of Mn and Co ions, respectively. The absorption structure at above 3.5 eV decreases gradually as the thickness grows, while the peak around 1.6-1.9 eV weakens slightly before it enhances again with film thickness above 430 nm, which can be explained by a combined effect of crystallinity improvement and increase in Mn4+/Mn3+ ratio.
关键词： optical properties,Mn1.56Co0.96Ni0.48O4 thin film,thickness dependence,chemical solution deposition,absorption structures
更新于2025-09-23 15:22:29
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Aerosol assisted chemical vapor deposition (AACVD) synthesis of nanostructured cauliflower patterning in MWCNT doped tungsten oxide
摘要： We report nanostructured tungsten oxide (WO) cauliflowers for the first time that are fabricated onto silica glass substrate at 400 °C by aerosol assisted chemical vapor deposition using tungsten hexacarbonyl and multiwalled CNTs in toluene. The deposited films are characterized by Scanning electron microscopy, Energy dispersive x-ray spectroscopy, X-ray diffractometry, Fourier transform infrared and UV–VIS spectroscopy and four-point probe for microstructural, optical and electrical properties. Surface morphology exhibits the growth of nanocauliflowers followed by the aggregation of spherical nanoparticles with high angle grain boundaries. Structural information reveals the transformation of triclinic to tetragonal phase with preferential switching from (0 2 0) to (0 0 1) plane having signatures of W-O-W symmetric vibration between 700cm-1 and 900 cm-1, somewhat perturbed by the addition of doping. In additions, films show inconsistent variation in electrical resistivity (15–109) Ω-cm due to agglomeration of MWCNTs at grain boundaries and appearance of 'nanocracks' due to ionic radii mismatch of tungsten and CNTs at higher doping ratios. Black color films present decrease in optical transmittance for range of 300–400 nm attributed to trapping sites and defects generated due to incorporation of multiwalled CNTs. The splitting of Fermi level as a result of incorporation of MWCNTs caused the increase of band gap energy in range of 3.18 eV, useful in tungsten oxide based new material system which can act as the light harvesting material and energy storage simultaneously.
关键词： Thin film,Tungsten oxide,Nanocauliflowers,AACVD
更新于2025-09-23 15:22:29
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Investigation of local geometrical structure, electronic state and magnetic properties of PLD grown Ni doped SnO2 thin films
摘要： We have investigated the ferromagnetic behavior, electronic states and local geometrical structure of Ni (2 and 10 at %) doped SnO2 thin films. The films were successfully fabricated with the help of pulsed laser deposition (PLD) technique on Si (100) substrate under ultrahigh vacuum (UHV) condition. X-ray diffraction (XRD) results revealed the single phase character of SnO2 rutile lattice structure with P42/mnm space group. The inclusion of Ni ions into SnO2 matrix induced oxygen vacancy (Vo), enhanced the distortion in octahedral local symmetry and reduced the oxidation state of the host Sn4+ (SnO2) to Sn3+ (Sn2O3) these details have been estimated by Raman scattering, Near edge X-ray absorption fine structure (NEXAFS) spectra at Ni L3,2 and O K edges. Further quantitative details on the local geometrical structure around Ni ions were obtained via fitting the experimental Fourier transforms EXAFS spectra |X(R)| with FEFF6 code. The magnetization measurements performed at room temperature (RT) infers that the observed magnetic behavior of the films seems to be relevant to the same crystal growth condition (UHV) and might not be limited directly to the Ni dopant concentrations. The FM signal and the role of surface defects have been discussed based spin-split impurity band difference in the saturation moments even with increase the Ni content. Hence, the similarity in Ni doped SnO2 films displayed ferromagnetic (FM) signal, and there was no significant Ferromagnetism etc. percolation mechanism.
关键词： surface defects,XANES spectra,SnO2 nanostructured thin film,PLD,local symmetry,XRD,NEXAFS
更新于2025-09-23 15:22:29
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Effects of substrate temperature and precursor amount on optical properties and microstructure of CVD deposited amorphous TiO2 thin films
摘要： In this research, TiO2 thin films were deposited on glass substrate by chemical vapor deposition using tetra isopropylorthotitanate as a precursor at low temperature. The TiO2 thin films were formed without using an oxygen source or annealing. Effects of substrate temperature and amount of the precursor on surface microstructure and optical properties of deposited TiO2 thin films were investigated. X-ray diffraction (XRD), UV-visible spectrophotometry and atomic force microscopy (AFM) were used to analyze the fabricated layers. The XRD analysis revealed that structure of all prepared layers was in amorphous phase. Analysis of AFM images showed that by increasing substrate temperature, the layer surfaces became rougher and simultaneously nanoparticle size was more uniform. Texture analysis revealed that increasing substrate temperature and decreasing precursor amount both increased surface isotropy. Thickness of layers was calculated by applying the Swanepoel method to the transmittance spectra. Variations in optical parameters were studied, including of optical band gap, refractive index, extinction coefficient, complex dielectric function, Urbach energy, single oscillator energy and dispersion energy. The results indicated that optical properties were functions of substrate temperature and precursor amount.
关键词： CVD,TiO2 thin film,Substrate temperature,Optical properties,Amorphous structure
更新于2025-09-23 15:22:29
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Piezoelectric and ferroelectric characteristics of P(VDF-TrFE) thin films on Pt and ITO substrates
摘要： Organic P(VDF-TrFE) 70/30 copolymer thin films were fabricated on Pt/Ti/SiO2/Si(1 1 1) and ITO/glass substrates at 140 °C using a spin coater. Both P(VDF-TrFE) thin films exhibited ferroelectric β-phase crystallinity, as confirmed by X-ray diffraction analysis. The polarization–electric hysteresis loops of the P(VDF-TrFE) thin films on the Pt and indium-tin-oxide substrates showed high remnant polarizations of 15.5 and 11.8 μC/cm2, respectively. Atomic force microscopy characterization showed rod-like features of the P(VDF-TrFE) thin films on both substrates, where larger rod diameters were observed on the Pt substrate compared to those fabricated on the ITO substrate. Piezoelectric force microscopy measurements further confirmed the superior piezoelectric and ferroelectric properties of the P(VDF-TrFE) thin films on the Pt substrate compared to those on the ITO substrate, which arose from the increased diameter of the rod-like features.
关键词： Piezoelectricity,Ferroelectricity,P(VDF-TrFE) thin film,ITO substrate,Pt substrate
更新于2025-09-23 15:22:29
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Effect of hydrodynamic conditions on the Cu(In,Ga)Se2 thin film growth by electrodeposition
摘要： In this paper, an experimental study about CIGS thin film growth due to hydrodynamic conditions variations on the working electrode surface is reported. Local hydrodynamic conditions were produced by the interaction of the natural convection flow with a non-conducting hemisphere placed on the working electrode surface. The electrodeposition process was made by a single bath with copper, indium, gallium and selenium ions to obtain CIGS thin films. The electrodes in the electrolytic cell were placed vertically. The as-electrodeposited CIGS thin film morphology near the hemisphere had a characteristic growth as a consequence of the local hydrodynamic conditions. CIGS thin film morphology and composition variations due to the wake and boundary layer were identified. With the CIGS film morphology obtained due to the presence of the wake was possible to represent the natural convection flow pattern on the Mo electrode surface. The CIGS thin film composition, inside and outside of the wake and throughout the boundary layer, was characterized. The gallium incorporation to the CIGS film was principally affected. As a consequence of this study, it was found that the atomic percentage of gallium in the CIGS film is related to deposition current density.
关键词： Electrodeposition,CIGS thin film,Natural convection flow
更新于2025-09-23 15:22:29
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On the anomaly in the electrical characteristics of thin film transistors with multi-layered sol-gel processed ZnO
摘要： A set of bottom-gate Zinc Oxide (ZnO) thin film transistors (TFTs) with active layers containing 1, 4 and 8 layers of spin-coated ZnO were fabricated and their electrical characteristics such as transistor transfer and capacitance-voltage characteristics were analyzed. The transconductance of the single-layered ZnO transistor shows a single peak. On the other hand, multiple peaks and humps were observed in the transconductance and capacitance-voltage characteristics of multi-layered ZnO transistors. The multi-layers were grown by reiteration of the spin-coating process, producing ZnO-ZnO interlayer-interfaces. The surface of the ZnO layer in contact with the ambient contains active sites, resulting in chemisorption of ambient gases such as oxygen prior to the deposition of subsequent layers. The chemisorbed species become negatively-charged and form charge sheets, depleting the surface/interface region. It was proposed that the formation of depletion layers at ZnO-ZnO interlayer-interfaces is the main cause for the observed anomaly.
关键词： Sol-gel,Zinc oxide,Spin-coating,Thin-film transistors,Electrical Properties,Interface Defects
更新于2025-09-23 15:22:29
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Free-standing black phosphorus thin films for flexible quasi-solid-state micro-supercapacitors with high volumetric power and energy density
摘要： Micro-supercapacitors (micro-SCs) are significant micro-scale power sources and energy storage components for miniaturized electronic and flexible devices, where electrodes play the key role in determining their electrochemical performance. The efficient intercalation of ions between the stacking layers of 2D layered materials (2DLM) makes them great candidates as thin film electrodes in micro-SCs, where one can achieve much enhanced volumetric capacitance. However, a great challenge is to develop a high-yield production method for high quality 2DLM thin film electrodes. In this work, we have successfully reported a scalable fabrication process for free-standing black phosphorous (BP) thin films, derived from the high quality few-layer BP nanoflakes via a modified electrochemical exfoliation route, for flexible quasi-solid-state micro-SCs (QMSCs). The as-fabricated QMSCs exhibit an excellent stable electrochemical performance at a high scan rate up to 100 V s-1. More importantly, our QMSC device can not only achieve an outstanding energy density of 3.63 mW h cm-3, a remarkable power density of 10.1 W cm-3 and a superior cycle span (94.3% capacity retention even after 50000 cycles), but also deliver the excellent mechanical flexibility is demonstrated by 91.3% capacity retention after 500 mechanical bending cycles. More interesting, to meet the energy density and power density needs for various practical applications, multiple QMSCs can be successfully integrated in parallel or in series, which is demonstrated by lighting up of the red light emitting diode (LED). The BP-based QMSCs can be patterned on a single substrate with flexible photodetectors based the same BP thin film to form a self-powered optoelectronic system.
关键词： thin film,black phosphorous,2D layered materials,micro-supercapacitors,energy storage
更新于2025-09-23 15:22:29