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- 2018
- thin-film transistors
- N2O plasma treatment.
- amorphous InGaZnO
- gate-bias stress
- stability
- Electronic Science and Technology
- Peking University
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Effect of pre-existing nuclei on crystallization during laser welding of Zr-based metallic glass
摘要： In this study, experiments are carried out in laser welding of a Zr-based (Zr52.5Ti5Al10Ni14Cu17.9) bulk metallic glass (BMG), pre-existing nuclei nucleus density has significant influence on its crystallization behavior. Based on the classical nucleation/growth theory, it is concluded that a small amount of pre-existing nuclei in a BMG can shift the time-temperature-transformation (TTT) curve from a well-known ‘C-shape’ to a ‘ε-shape.’ This result provides fundamental understanding on why the shape of the TTT curve for a heating process is different from that for a cooling process for the same BMG. Two quality factors were defined as a measure of the effect of pre-existing nucleus density. By integrating the classical nucleation/growth theory with the heat transfer model, the evolution of crystalline phase during laser welding for a BMG with pre-existing nuclei was studied, and the modeling predictions compared favorably with the experimental results.
关键词： Crystallization,Nucleation and growth,Laser processing,Metallic glasses,Amorphous alloys
更新于2025-11-28 14:24:20
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Microstructure and properties of laser interference crystallized amorphous FeSiB ribbon
摘要： The influence of Q-switched pulsed Nd:YAG laser interference heating, using 120 mJ of pulse energy and a variable number of consecutive pulses, on the microstructure and magnetic properties of amorphous Fe80Si11B9 alloy was examined. Microstructural analysis, using light, scanning and transmission electron microscopy, was complemented by results of M?ssbauer spectroscopy and measurement of magnetic properties (vibrating sample magnetometer). Periodically distributed crystallized micro-areas, *10 lm in diameter, in an amorphous matrix were produced by the treatments. Magnetization measurements showed that the as-cast ribbon and laser light irradiated samples are magnetically soft materials. The results lead to the conclusion that the dots corresponding to the laser modified regions exhibit a perpendicular magnetic anisotropy.
关键词： Laser interference heating,SEM,TEM,FeSiB amorphous alloy,Magnetic properties
更新于2025-11-14 17:04:02
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Platinum-enhanced amorphous TiO2-filled mesoporous TiO2 crystals for the photocatalytic mineralization of tetracycline hydrochloride
摘要： The adsorption ability and photoactivity of a photocatalyst largely determine the mineralization efficiency of antibiotics. Herein, aiming to enhance the adsorption and mineralization of antibiotics, we constructed a hierarchical porous core-shell structure by filling amorphous TiO2 in the pores of Pt-doped mesoporous TiO2 crystals (MCs). The physical–chemical properties of the prepared samples were investigated by surface photovoltage spectroscopy, X-ray photoelectron spectroscope, etc. Adsorption and photocatalysis experiments were conducted with tetracycline hydrochloride as the model antibiotic. Pt nanoparticles doped at the interface of the rutile-amorphous homojunction remarkably enhanced the built-in electric field. The enhanced electric field increased the hole transfer to the catalyst surface, and the Pt doping treatment promoted the growth of amorphous TiO2 into the mesopores of the MCs. The optimization increased the surface area of the catalyst without increasing the thickness of the amorphous TiO2 shell, thereby reducing the charge migration distance from the core–shell interface to the catalyst surface. The adsorption amount and mineralization efficiency of tetracycline hydrochloride for the porous core-shell composite were 6.7 and 3.8 times of those for MCs, respectively.
关键词： Crystal,Amorphous TiO2,TCH,Mesoporous TiO2,SPV,Charge carriers
更新于2025-11-14 17:04:02
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Correlation of acetylene plasma discharge environment and the optical and electronic properties of the hydrogenated amorphous carbon films
摘要： Thin films from polymeric and graphitic hydrogenated amorphous carbon (a-C:H) were deposited over a glass substrate from acetylene (C2H2) plasma by using a conventional plasma enhanced chemical vapor deposition (PECVD). Radio frequency capacitively coupled plasma (RF CCP) source operating at a frequency of 13.56 MHz was used for generation of the discharge. Optical emission spectroscopy (OES) results showed strong optical emissions from diacetylene ion C4H2+ at a wavelength of 506 nm. The energy dispersive X-Ray (EDS) measurements illustrated that the carbon content in the deposited films increased with increasing of power. The Raman and IR results demonstrated that the films deposited at low bias voltages 340 V are so called polymeric a-C:H with high sp3 fraction and high hydrogen content, while the films deposited at high bias voltages 877 V are so called graphitic a-C:H with low sp3 fraction and low hydrogen content. Quantitative information were obtained from fitting the high asymmetrical vibrational modes of Raman and IR spectra by using Fano model expression together with Lorentzian function. The results presented here point out that there is a relation between the intensity of C4H2+ ion emissions and the deposited films properties.
关键词： Optical Emission,diacetylene ion,RF CCP,Hydrogenated amorphous carbon,FTIR,Raman spectroscopy
更新于2025-11-14 15:30:11
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Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide
摘要： Gold doping induced strong enhancement of carbon quantum dots fluorescence and oxygen evolution reaction catalytic activity of amorphous cobalt hydroxide. Water splitting using electrocatalysts is expected to provide an alternative green energy source to meet increasing energy demands as well as addressing environmental concerns related to fossil fuels. Herein, we report one-step synthesis of sulfur, nitrogen and Au-doped carbon quantum dots (Au-SCQDs) and strong enhancement of fluorescence intensity and oxygen evolution reaction (OER) catalytic activity of amorphous Co(OH)2 nanoparticles compared to pure Co(OH)2 as well as commercial RuO2 and Pt/C catalysts. Au doping into sulfur and nitrogen co-doped CQDs showed over seventy times enhanced fluorescence. OER studies of amorphous-Co(OH)2 incorporated Au-SCQDs produced current density of 178 mA cm?2 at the applied potential of 2.07 V whereas un-doped Co(OH)2 showed current density of 59 mA cm?2. To produce geometric current density of 10 mA cm?2, amorphous Co(OH)2-Au-SCQDs (CSA) required 388–456 mV overpotential depending on the Au ion concentration used for preparing the Au-SCQDs, which is equal to or lower than overpotential required by commercial electrocatalysts. The strongly enhanced OER activity of Co(OH)2-Au-SCQDs (CSA) was attributed to the presence of electronegative metallic conducting Au atoms along with the high catalytic surface area of amorphous Co(OH)2. The present studies demonstrate a new method of exploiting amorphous Co(OH)2NPs electrocatalysts that could provide more catalytically active sites by integrating an electronegative conducting Au atom doped SCQDs matrix.
关键词： amorphous cobalt hydroxide,fluorescence,water splitting,Gold doping,carbon quantum dots,oxygen evolution reaction,electrocatalysts
更新于2025-10-22 19:40:53
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Two-dimensional amorphous heterostructures of Ag/a-WO3- for high-efficiency photocatalytic performance
摘要： Synergistic photocatalysis is an important concept for designing the high-efficiency catalysis for fundamental research and technical applications. In this study a well-defined synergistic photocatalysis system is realized by the 2D amorphous heterostructures (2DAHs) Ag/a-WO3-x, which are constructed by Ag nanoparticles on 2D amorphous tungsten oxide (a-WO3-x) fabricated via supercritical CO2 method. We demonstrate theoretically that the oxygen evolution reactions (OER), characterized by photocurrent response, have been dramatically improved in Ag/a-WO3-x than those of both single a-WO3-x and Ag/WO3 systems. Such an enhanced photoelectrochemical performance attributes to the superposition effect of amorphous effect catalysis and local surface plasmon resonances (LSPR) catalysis. More interestingly, the ab initio density-functional theory calculations reveal that the amorphous effect catalysis ascribes to the unique d-d tail states coupling of both Ag and W atoms in the 2DAHs. Overall, our findings not only propose the prototype of synergistic photocatalysis, but also provide a new methodology to the design of novel catalyst.
关键词： 2D amorphous tungsten oxide,amorphous effect catalysis,synergistic photocatalysis,d-d tail states coupling,2D amorphous heterostructures Ag/a-WO3-x
更新于2025-09-23 15:23:52
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An optically-gated transistor comprised of amorphous M+Ge2Se3 (M=Cu, Sn) for accessing and continuously programming a memristor
摘要： We demonstrate that a device comprised of sputtered amorphous chalcogenide Ge2Se3/M+Ge2Se3 (M = Sn or Cu) alternating layers, functions as an optically-gated transistor (OGT) and can be used as an access transistor for a memristor memory element. This transistor has only two electrically connected terminals (source and drain), with the gate being optically controlled, thus allowing the transistor to operate only in the presence of light (385 – 1200 nm). The switching speed of the OGTs is less than 15 μs. The OGT is demonstrated in series with a Ge2Se3+W memristor, where we show that by altering the light intensity on the OGT gate, the memristor can be programmed to a continuous range of non-volatile memory states using the saturation current of the OGT as a programming compliance current. By having a continuous range of non-volatile states, one memory cell can potentially achieve 2n levels. This high density, combined with optical programmability, enables hybrid electronic/photonic memory.
关键词： access transistor,chalcogenide,resistive RAM,optoelectronic,selector,amorphous,memristor
更新于2025-09-23 15:23:52
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Computational Study on Interfaces and Interface Defects of Amorphous Silica and Silicon
摘要： The amorphous SiO2/Si interface is arguably the most important part in semiconductor technology, strongly influencing the device reliability. Its electronic structure is affected by the defects, majorly the dangling bonds known as Pb-type defects, which have been studied for decades. These defects are usually passivated by hydrogen atoms in device processing, which eliminates the defect levels in the silicon bandgap and thus removes their electric activity. However, when the interface is exposed to ionization radiation, the passivated defects can be reactivated by the protons generated by radiation, which significantly affects the device performance and causes reliability issues. In this review, computational studies on the amorphous SiO2/Si interface and interface defects are summarized, including the modeling of the interface, the main interface defects, and their depassivation, and compared to experimental results. The hyperfine parameters are emphasized, because they are essential to identify the structures of the interface defects. The defect levels and depassivation of the defects are also emphasized, because the former directly affect the device performance and the latter directly generates the dangling bonds in the interface.
关键词： depassivation,ionizing damage,interface defects,amorphous interfaces,first-principles calculations
更新于2025-09-23 15:23:52
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A novel silicon heterojunction IBC process flow using partial etching of doped a-Si:H to switch from hole contact to electron contact <i>in situ</i> with efficiencies close to 23%
摘要： We present a novel process sequence to simplify the rear‐side patterning of the silicon heterojunction interdigitated back contact (HJ IBC) cells. In this approach, interdigitated strips of a‐Si:H (i/p+) hole contact and a‐Si:H (i/n+) electron contact are achieved by partially etching a blanket a‐Si:H (i/p+) stack through an SiOx hard mask to remove only the p+ a‐Si:H layer and replace it with an n+ a‐Si:H layer, thereby switching from a hole contact to an electron contact in situ, without having to remove the entire passivation. This eliminates the ex situ wet clean after dry etching and also prevents re‐exposure of the crystalline silicon surface during rear‐side processing. Using a well‐controlled process, high‐quality passivation is maintained throughout the rear‐side process sequence leading to high open‐circuit voltages (VOC). A slightly higher contact resistance at the electron contact leads to a slightly higher fill factor (FF) loss due to series resistance for cells from the partial etch route, but the FF loss due to J02‐type recombination is lower, compared with reference cells. As a result, the best cell from the partial etch route has an efficiency of 22.9% and a VOC of 729 mV, nearly identical to the best reference cell, demonstrating that the developed partial etch process can be successfully implemented to achieve cell performance comparable with reference, but with a simpler, cheaper, and faster process sequence.
关键词： interdigitated back contact (IBC),H2 plasma,amorphous silicon,heterojunction,dry etch,process simplification,NF3/Ar plasma,in situ processing
更新于2025-09-23 15:23:52
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24.5: Back-Channel-Etched a-IGZO TFTs with TiO <sub/>2</sub> :Nb Protective Layer
摘要： A back-channel-etched (BCE) process for the fabrication of a-IGZO TFTs is demonstrated, in which conductive TiO2:Nb (TNO) thin film is used to serve as protective layer for the a-IGZO active layer. TNO film could excellently protect a-IGZO due to its ultra-small surface roughness. With treatment by N2O plasma + 200°C annealing, the conductive TNO can be converted into an insulator to serve as an in situ passivation layer. Besides, the TNO in the source–drain (S-D) region remain conductive due to the protection of S-D electrodes, which could be proved by the XPS results. Compare with the conventional device without TNO protective layer, the S-D parasitic resistance (RSD) of devices with 1 nm and 5 nm TNO is significantly reduced. The positive bias stress stability is improved as well for the devices with TNO in situ passivation layer.
关键词： amorphous indium gallium zinc oxide (a-IGZO),Nb doped TiO2 (TNO),thin film transistors (TFTs),back-channel-etched (BCE) process
更新于2025-09-23 15:23:52