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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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Modifying the Electronic Properties of Se/n‐Si Heterostructure Using Electrolysis
摘要： Heterostructures of dissimilar crystalline materials are key in the development of photoelectronic devices. Such structures rely on matching lattice constants for efficient transport. Nevertheless, an amorphous material, amorphous Se is becoming important in high-energy photoelectronics. Thus there is a need to understand the heterostructures it forms with conventional crystalline materials. Since the transport properties of such heterostructures will be limited by lattice mismatches, methods to improve transport are necessary. We investigated the effect of electrolysis on the electronic properties of Se based multilayer films deposited on n-type silicon (Se/n-Si) and showed that conduction and photoresponse can be changed by electrolysis processing. The Se surface of the Se/n-Si samples was used as an anode in the electrolysis of NaCl solution. Afterwards, the samples were measured using current–voltage and capacitance–voltage variations in dark conditions and under illumination. Electrolysis processed samples showed higher conduction current and photocurrent, compared to samples not used in electrolysis. This is due to the introduction of Cl into the Se, which affects carrier lifetimes: increasing hole lifetime and reducing electron lifetime. We therefore suggest that electrolysis can be applied to modify the electronic properties of Se/n-Si heterostructures.
关键词： chalcogenide semiconductor,amorphous selenium,heterostructures,electrochemical
更新于2025-09-23 15:19:57
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Amorphous Boron Suboxide
摘要： We study the atomic structure and the electronic and mechanical properties of amorphous boron suboxide (B6O) using an ab initio molecular dynamic technique. The amorphous network is attained from the rapid solidification of the melt and found to consist of boron and oxygen rich regions. In the boron rich regions, boron atoms form mostly perfect or imperfect pentagonal pyramid like configurations that normally yield the construction of ideal and incomplete B12 molecules in the model. In addition to the B12 molecules, we also observe the development of a pentagonal bipyramid (B7) molecule in the noncrystalline structure. In the oxygen rich regions, on the other hand, boron and oxygen atoms form threefold and twofold coordinated motifs, respectively. The boron rich and oxygen rich regions indeed represent structurally the characteristic of amorphous boron and boron trioxide (B2O3). The amorphous phase possess a small band gap energy with respect to the crystal. On the bases of the localization of the tail states, we suggest that the p-type doping might be more convenient than the n-type doping in amorphous B6O. Bulk modulus and Vickers hardness of the non-crystalline configuration is estimated to be 106 and 13-18 GPa, respectively, which are noticeably less than those of the crystalline structure. Such a noticeable decrease in the mechanical properties is attributed to the presence of open structured B2O3 glassy domains in the amorphous model.
关键词： hardness,amorphous,boron suboxide
更新于2025-09-19 17:15:36
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First-principles calculations on effects of Al and Ga dopants on atomic and electronic structures of amorphous Ge <sub/>2</sub> Sb <sub/>2</sub> Te <sub/>5</sub>
摘要： Effects of post-transition metal dopants M (M = Al, Zn, and Ga) on structural and electronic properties of amorphous Ge2Sb2Te5 (a-GST) are investigated through first-principles calculations based on the density functional theory. The doped a-GST is generated through the melt-quench procedure using molecular dynamics simulations. It is found that the three dopants behave similarly in a-GST, and they are mostly coordinated by Te atoms in tetrahedral geometry, which is similar to those in crystalline MxTey. This is in contrast with crystalline GST wherein the most stable position of dopant M is the octahedral vacancy site. The number of wrong bonds such as Ge–Ge, Ge–Sb, or Sb–Sb increases as dopant atoms predominantly bond with Te atoms. The number of 4-fold ring structures, especially ABAB-type, decreases significantly, explaining the enhanced thermal stability of doped a-GST in the experiment. The bandgap estimated from density of states and the optical gap obtained from Tauc plot increase upon doping, which is also in good agreement with the experiment. By successfully relating the experimental doping effects and changes in the atomic structure, we believe that the present work can serve as a key to offer better retention and lower power consumption in phase-change memory.
关键词： amorphous Ge2Sb2Te5,electronic structures,first-principles calculations,atomic structures,Al and Ga dopants
更新于2025-09-19 17:15:36
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[Lecture Notes in Electrical Engineering] Sensors Volume 539 (Proceedings of the Fourth National Conference on Sensors, February 21-23, 2018, Catania, Italy) || Portable Optoelectronic System for Monitoring Enzymatic Chemiluminescent Reaction
摘要： This work presents a portable lab-on-chip system, based on thin film electronic devices and an all-glass microfluidic network, for the real-time monitoring of enzymatic chemiluminescent reactions. The microfluidic network is patterned, through wet etching, in a 1.1 mm-thick glass substrate that is subsequently bonded to a 0.5 mm-thick glass substrate. The electronic devices are amorphous silicon p-i-n photosensors, deposited on the outer side of the thinner glass substrate. The photosensors, the microfluidic network and the electronic boards reading out the photodiodes' current are enclosed in a small metallic box (10 × 8 × 15 cm3) in order to ensure shielding from electromagnetic interferences. Preliminary tests have been performed immobilizing horseradish peroxidase on the inner wall of the microchannel as model enzyme for detecting hydrogen peroxide. Limits of detection and quantification equal to 18 and 60 μM, respectively, have been found. These values are comparable to the best performances reported in literature for chemiluminescent-based optofluidic sensors.
关键词： Amorphous silicon,Photosensors,Enzymatic reactions,Anodic bonding,Horseradish peroxidase,Microfluidics
更新于2025-09-19 17:15:36
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Hybridizing NiCo2O4 and amorphous NixCoy layered double hydroxides with remarkably improved activity towards the efficient overall water splitting
摘要： Overall water splitting is an attractive technology to produce clean hydrogen and oxygen. In this study, we constructed amorphous NixCoy layered double hydroxide (LDH) hybridized with three-dimensional NiCo2O4 to fabricate core-shell nanowire array on Ni foam (NiCo2O4@NixCoy LDH/NF) as highly efficient electrocatalyst for overall water electrolysis. By tuning the Ni/Co molar ratio in NixCoy LDH, extremely low overpotentials of 193 mV for oxygen evolution reaction (OER) and 115 mV for hydrogen evolution reaction (HER) at a current density of 10 mA cm?2 can be achieved for the NiCo2O4@Ni0.796Co LDH/NF. Detailed investigations verify that the hybrid structure can increase intrinsic activity of the NiCo2O4@Ni0.796Co LDH/NF and enhance the charge-transfer rate. Moreover, a strong electronic interaction between the heterogeneous elements Ni and Co at the interface of the NiCo2O4 and NixCoy LDH might ultimately influence the catalytic performance.
关键词： bifunctional electrocatalyst,nanowire arrays,amorphous material,layered double hydroxide,water splitting
更新于2025-09-19 17:15:36
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European Microscopy Congress 2016: Proceedings || Revisiting the EELS analyses and its coupling with multi-wavelength Raman spectroscopy: the case of hydrogenated amorphous carbon thin films
摘要： Thanks to the long-term stability of their properties, hydrogenated amorphous carbon (a:C-H) thin films are very promising materials for numerous applications including coatings for spatial applications.1 In order to improve their performances, a full understanding of their local chemistry is highly required. Fifteen years ago, according to the seminal work of Ferrari et al.,2 EELS was the most used technique to get such kind of quantitative information on these materials. Nowadays the complexity of the physics phenomena behind EELS is well known3 and this technique is regarded as time-consuming and difficult to interpret properly. Other optical techniques such as Raman spectroscopy are now clearly favored by the scientific community. However they still lack of the spatial resolution that EELS in a STEM offers for getting direct chemical information. a-C:H thin films, with a thickness around 300 nm, were deposited on a Si wafer and submitted to isothermal annealing at 500°C with different annealing times up to 2500 minutes. The hydrogen content was monitored by multi-wavelength (MW) Raman using a set of reference materials. To determine the sp2 fraction (sp2 %) from core-loss EELS, the R ratio (R = Iπ*(ΔE)/I(π*(ΔE)+σ*(ΔE)) was determined first by taking into account the asymmetry of the π* character (Fig. 1a).4,5 This value was then normalized by the maximum R value (RREF) that could be obtained from a HOPG sample in the same experimental condition using relativistic calculations (Fig. 1b).6 When needed, this method was also slightly modified to take into account the contribution of heterospecies. In addition, the mass density and the oxygen content was derived from low-loss and core-loss spectra, respectively. The EELS C-K edge spectra (Fig. 2a) present all a typical signature of amorphous carbons. However, the intensity of the massif above 292 eV differs from sample to sample and clearly highlights a slight variation of the sp2 %. The samples annealed 2500 min also presents a supplementary peak (red arrow in Fig. 2a), which is related to the oxidation of the thin film. As expected, the sp2 % increases with the annealing time (Fig. 2b). This effect is related to the H desorption of the thin films as monitored by Raman spectroscopy. Two samples do not follow this trend: the as-deposited sample and the sample annealed 2500 minutes. This latter presents a strong oxidation, leading to a decrease of the sp2 %. On the other hand, the as-deposited sample shows variation of the C-K edge fine structures (Fig. 3a) highlighting chemical inhomogneities in the thin film. This sample presents a strong gradient of the sp2 % induced by the deposition process (Fig. 3b) which is cured with the annealing time. All these results will be detailed together with the influence of the oxidation on the chemical and physical properties. In addition, the coupling of MW Raman, infrared and EELS spectroscopies to extract a wealth of chemical information will be discussed. Our results provide a complete combination of C-hybridization, spatial elemental analyses and structural defects studies for shedding light on these complex materials.7,8
关键词： Raman,Hydrogenated Amorphous Carbon,EELS,sp2 fraction
更新于2025-09-19 17:15:36
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Synthesis of Cu2O/Carbon film/NiCoB-GO Heterostructure Photocathode for Efficient Photoelectrochemical Water Splitting
摘要： Photoelectrochemical (PEC) water splitting offers a promising way to convert solar energy to chemical energy. The electron transfer rate and surface-catalyzed ability toward hydrogen evolution reaction (HER) play the key roles in the efficiency of PEC water splitting. In this work, a Cu2O/Carbon film/NiCoB-GO heterostructure photocathode is fabricated. Among them, thickness-controllable carbon film served as the electron transport and protective layer with favourable optical property, NiCoB-GO amorphous catalyst displays the efficient performance towards HER in neutral condition. The optimized photocathode shows the PEC-HER performance with a photocurrent density of -2.9 mA/cm2 at 0 V vs. RHE, and it also presents better stability than bare Cu2O. This work provides a novel heterostructure photocathode for promoting solar-driven PEC water splitting efficiently.
关键词： Femtosecond transient absorption spectroscopy,Photoelectrochemical water splitting,Electron transport path,Carbon film,Amorphous catalyst
更新于2025-09-19 17:15:36
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35.3: Self-formed nano-scale metal-oxide contact interlayer for amorphous silicon tin oxide TFTs
摘要： The formation of metal oxide interlayer is induced by pre-annealing process in the amorphous Silicon-Tin-Oxide thin film transistors (a-STO TFTs) with Mo source/drain electrodes. Cross-sectional high-resolution transmission electron microscopy image confirmed the formation of ~8nm MoOx interlayer. The introduction of MoOx interlayer between Mo electrodes and a-STO improved the electron injection in a-STO TFT. Mo adjacent to the a-STO semiconductor gets oxygen atoms from the oxygen-rich surface of a-STO film to form MoOx interlayer. The self-formed MoOx interlayer acting as an efficient interface modification layer could conduce to the stepwise internal transport barrier formation while blocking Mo atoms diffuse into a-STO layer, which would contribute to the formation of ohmic contact between Mo and a-STO film.
关键词： self-formed interlayer,amorphous Silicon-Tin-Oxide,work function,Thin film transistors,ohmic contact
更新于2025-09-19 17:15:36
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Tricolor mechanochromic luminescence of an organic two-component dye: visualization of a crystalline state and two amorphous states
摘要： Solid-state emissive dyes with mechanochromic luminescence (MCL) properties change their emission colors upon exposure to mechanical stimuli. During the recent rapid advances in the area of MCL, considerable efforts have been focused on elucidating the MCL behavior of single-component dyes that can switch their solid-state emission between two colors. Herein, a novel strategy to achieve tricolor MCL is presented, which is based on mixing two organic dyes that exhibit poor MCL or no MCL properties, respectively. We propose that the tricolor MCL of the two-component dye should be attributed to the transition of the fraction with poor MCL properties from a crystalline to two amorphous states, specifically a perfectly amorphous and a proto-crystalline amorphous state. The present system should have advantages in terms of the availability of MCL dyes and the variety of potential combinations of two-component dyes. By making a use of the underlying design principle developed in this study, a wide variety of new MCL systems should be accessible, which should also accelerate the investigation of practical applications of MCL dyes.
关键词： mechanochromic luminescence,crystalline state,amorphous states,two-component dye,tricolor
更新于2025-09-19 17:15:36
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Photo and thermal induced Bi2Se3 formation from Bi/GeSe2 hetero junction layer for topological insulator
摘要： In the present paper, we report the evolution of Bi2Se3 topological phase from the Bi diffusion into GeSe2 layer in the Bi/GeSe2 hetero junction film with light and thermal energy. The photo and thermal induced changes in the structural and optical properties of thermally evaporated Bi/GeSe2 bilayer film has been studied by various characterization techniques. The amorphous to crystalline phase transition and the formation of Bi2Se3 topological phase was confirmed from the X-ray diffraction analysis. The deposition as well as diffusion of Bi into GeSe2 layer changed the optical constants like transmitivity, absorption power, optical band gap, Urbach energy, Tauc parameter as studied from UV–Vis–NIR spectroscopy. The transmission power decreased after thermal annealing and laser irradiation where the reverse effect was found in case of absorption coefficient. The optical band gap decreased after diffusion which can be explained on the basis of density of defect states with an increase in disorder. Scanning electron microscopy investigations showed that the surface morphology was influenced by the diffusion phenomena. The Raman analysis also confirms the Bi2Se3 phase evolution with appropriate vibrational peaks. The modifications in optical parameters with thermal and light induced diffusion can be used in various optical applications using such metal/chalcogenides heterojunction layers.
关键词： Amorphous materials,Optical properties,Bi2Se3 phase,Chalcogenides,Thin films,Band gap
更新于2025-09-19 17:15:36