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Femtosecond laser surface engineering of biopolymer ceramic scaffolds coated with ZnO by low temperature atomic layer deposition method
摘要： Surface femtosecond laser texturing of biopolymer and biopolymer/ceramic composites with subsequent ZnO film deposition on the samples by low temperature Atomic Layer Deposition (ALD) method was performed. In the current study, the deposition of ZnO layers was implemented at temperature 50 °C under pressure of 2 mbar. In order to investigate the effect of diverse ZnO thin films thickness, 100 or 500 repeating ALD cycles were applied. The samples were exposed to ultra-short laser pulses of 130 fs duration generated by a CPA (chirped pulse amplifier) Ti:Sapphire laser system. The artificial scaffolds were irradiated by varying the laser fluence (0.2 J/cm2, 0.41 J/cm2 and 2.07 J/cm2) and the number of applied laser pulses (N = 1, 2, 5 and 10). The morphology and chemical properties of the treated samples were evaluated by Scanning Electronic Microscopy, Energy-Dispersive X-ray Spectroscopy and X-ray photoelectron spectroscopy. By combining fs laser modification with low temperature ALD method, essentially improved bioactivity properties of hybrid organic–inorganic bone tissue scaffolds could be achieved, which is of great importance for future tissue engineering application of the samples.
关键词： Atomic layer deposition,Biopolymer/ceramic composites,Femtosecond laser modification,Tissue engineering
更新于2025-09-23 15:21:01
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Effects of postmetallization annealing on interface properties of Al <sub/>2</sub> O <sub/>3</sub> /GaN structures
摘要： In this study, we investigated the e?ects of postmetallization annealing (PMA) on the interface properties of GaN metal–oxide–semiconductor (MOS) structures using Al2O3 prepared by atomic layer deposition. Excellent capacitance–voltage (C–V ) characteristics without frequency dispersion were observed in the MOS sample after PMA in N2 ambient at 300–400 °C. The PMA sample showed state densities of only at most 4 ' 1010 cm%1 eV%1. A geometric phase analysis of transmission electron microscopy images after PMA revealed a uniform distribution of the lattice constant near the Al2O3/GaN interface, leading to the improved bond termination and bonding order con?guration along the interface.
关键词： atomic layer deposition,capacitance–voltage characteristics,Al2O3/GaN structures,interface properties,postmetallization annealing
更新于2025-09-23 15:21:01
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Silicon Nanoparticle Films Infilled with Al <sub/>2</sub> O <sub/>3</sub> using Atomic Layer Deposition for Photosensor, Light Emission and Photovoltaic Applications
摘要： Solution-processed thin films of crystalline silicon nanoparticles (Si NPs) have a great potential for a wide variety of electronic and optoelectronic applications. However, such films are inherently unstable due to their huge surface-to-volume ratios and high surface energies, making them prone to degradation associated to spontaneous oxidation in ambient conditions. In this work, we explore the use of atomic layer deposition (ALD) as a means to stabilize and potentially functionalize solution-processed thin films of Si NPs for (opto)electronics e.g. thin-film transistors, photosensors, light-emitting devices, and photovoltaics. We prepared films of randomly distributed Si NPs with ultrashort surface ligands (Si-H termination) using wet-chemistry and spray-coating and then use ALD to infill the films with Al2O3. Through microscopy and optical structural/morphological analysis, we demonstrate the achievability of ALD infilling of films of Si NPs and probe the stability of these films against oxidation. Moreover, we show that the ALD infilling leads to changes in the light emission properties of the Si NP films, including a relative quenching of disorder-related emission features and variations in surface-related dielectric confinement effects. Our studies reveal ALD as a relevant technique toward manufacturing de facto robust, functional nanomaterials based on Si NPs and on nanoscale silicon materials more generally.
关键词： Photoluminescence properties,Nanoparticle film infilling,Silicon nanocrystal films,Air stability,Atomic layer deposition
更新于2025-09-23 15:21:01
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Improving the leakage characteristics and efficiency of GaN-based micro-light-emitting diode with optimized passivation
摘要： We investigated the effect of atomic layer deposition (ALD) Al2O3 (50 nm)/plasma-enhanced chemical vapour deposition (PECVD) SiO2 (250 nm) and PECVD SiO2 (300 nm) passivation layers on the leakage current and efficiency of InGaN-based micro-LEDs with different sizes. The micro-LEDs with the single passivation layer gave the ideality factors of about 2.0, while that with the double layer exhibited values smaller than 2.0. The micro-LEDs with the double passivation layer exhibited external quantum efficiency peaks at lower current density compared to those with the single layer. It was shown that smaller micro-LEDs were more sensitively dependent on the types of the passivation layers. These results exhibit that the ALD-Al2O3/PECVD-SiO2 passivation layer is more effective in suppressing the sidewall damage-induced current than the PECVD-SiO2 layer.
关键词： Atomic layer deposition,Micro-LED,Passivation,GaN
更新于2025-09-23 15:21:01
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Ultrathin TiO2-coated SiO2 nanoparticles as light scattering centers for quantum dot-sensitized solar cells
摘要： SiO2/TiO2 core/shell nanoparticles (ST-NPs) with an ultrathin and conformal TiO2 shell were fabricated via atomic layer deposition (ALD) technique with a specially-designed rotary reactor. We successfully employed the ST-NPs as light scattering centers in a mesoporous TiO2 photoanode in quantum dot (QD)-sensitized solar cells (QDSSCs). ST-NPs enhanced the light scattering in the TiO2 photoanode without deterioration of QD loading behavior. Consequently, visible light absorbance was improved in the PbS QDs-sensitized TiO2 photoanode, and thus the photocurrent density increased from 14 to 17 mA/cm2. Detailed electron microscopy was utilized to reveal the uniqueness of the ultrathin TiO2 shell in ST-NPs, and in-depth electrochemical impedance spectroscopy divulged the increase in photogenerated carrier lifetime and improved recombination resistance for the QDSSC with ST-NPs.
关键词： Core-shell,SiO2,Atomic layer deposition,QDSSCs,Light scattering
更新于2025-09-23 15:21:01
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Tunable Localized Surface Plasmon Resonance and Broadband Visible Photo-response of Cu Nanoparticles/ZnO Surfaces
摘要： Plasmonic Cu nanoparticles (NP) were successfully deposited on ZnO substrates by atomic layer deposition (ALD) owing to the Volmer–Weber island growth mode. An evolution from Cu NP to continuous Cu films was observed with increasing the number of ALD cycles. Real and imaginary parts of the NP dielectric functions, determined by spectroscopic ellipsometry using an effective medium approach, evidence a localized surface plasmon resonance that can be tuned between the visible and near infrared ranges by controlling the interparticle spacing and size of the NP. The resulting Cu NP/ ZnO device shows an enhanced photo-response under white light illumination with good responsivity values, fast response times and stability under dark/light cycles. The significant photocurrent detected for this device is related with the hot electron generation at the NP surface and injection into the conduction band of the ZnO. The possibility of tuning the plasmon resonance together with the photo-responsivity of the device is promising in many applications related with photo-detection, photonics and photovoltaics.
关键词： atomic layer deposition,hot electrons,copper nanoparticles,photodetectors,localized surface plasmon resonance
更新于2025-09-23 15:21:01
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In Situ SiO <sub/>2</sub> Passivation of Epitaxial (100) and (110)InGaAs by Exploiting TaSiO <sub/><i>x</i> </sub> Atomic Layer Deposition Process
摘要： In this work, an in situ SiO2 passivation technique using atomic layer deposition (ALD) during the growth of gate dielectric TaSiOx on solid-source molecular beam epitaxy grown (100)InxGa1?xAs and (110)InxGa1?xAs on InP substrates is reported. X-ray reciprocal space mapping demonstrated quasi-lattice matched InxGa1?xAs epitaxy on crystallographically oriented InP substrates. Cross-sectional transmission electron microscopy revealed sharp heterointerfaces between ALD TaSiOx and (100) and (110)InxGa1?xAs epilayers, wherein the presence of a consistent growth of an ～0.8 nm intentionally formed SiO2 interfacial passivating layer (IPL) is also observed on each of (100) and (110)InxGa1?xAs. X-ray photoelectron spectroscopy (XPS) revealed the incorporation of SiO2 in the composite TaSiOx, and valence band offset (ΔEV) values for TaSiOx relative to (100) and (110)InxGa1?xAs orientations of 2.52 ± 0.05 and 2.65 ± 0.05 eV, respectively, were extracted. The conduction band offset (ΔEC) was calculated to be 1.3 ± 0.1 eV for (100)InxGa1?xAs and 1.43 ± 0.1 eV for (110)InxGa1?xAs, using TaSiOx band gap values of 4.60 and 4.82 eV, respectively, determined from the fitted O 1s XPS loss spectra, and the literature-reported composition-dependent InxGa1?xAs band gap. The in situ passivation of InxGa1?xAs using SiO2 IPL during ALD of TaSiOx and the relatively large ΔEV and ΔEC values reported in this work are expected to aid in the future development of thermodynamically stable high-κ gate dielectrics on InxGa1?xAs with reduced gate leakage, particularly under low-power device operation.
关键词： in situ SiO2 passivation,atomic layer deposition,InxGa1?xAs,band alignment,TaSiOx,gate dielectric
更新于2025-09-23 15:21:01
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Electrical characteristics analyses of zinc-oxide based MIS structure grown by atomic layer deposition
摘要： The ZnO films are grown on the p-type Si for metal-insulator-semiconductor (MIS) type Schottky barrier diode (SBHS) fabrication by atomic layer deposition (ALD) method. The electrical characteristics of the three diodes called as D1, D2 and D3 have been investigated. The surface characteristics and thin film in structure were detected by secondary ion mass spectrometry (SIMS) and atomic force microscopy (AFM). The current-voltage (I-V) properties of Al/ZnO/p-Si structures were analyzed in the dark at room temperature. The electrical specifications such as, barrier height (?b) ideality factor (n) and series resistance (Rs) of these structures were examined by Norde’s function, Cheung method and thermionic emission (TE) theory. Barrier height values computed from Cheung and I-V method was found to be different from each other. Interface state density (Dit) of these structures was studied using the I-V properties. The non-ideal behavior of measured characteristics advised the presence of interface conditions. The acquired results imply that the fabricated diodes can be used for NIR Schottky photo detector applications.
关键词： ZnO,series resistance,ideality factor,Atomic Layer Deposition,Schottky photo detector
更新于2025-09-23 15:21:01
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Investigation of the Physical Properties of Plasma Enhanced Atomic Layer Deposited Silicon Nitride as Etch Stopper
摘要： Correlations between physical properties linking film quality with wet etch rate (WER), one of the leading figures of merit, in plasma-enhanced atomic layer deposition (PEALD) grown silicon nitride (SiNx) films remain largely unresearched. Achieving a low WER of a SiNx film is especially significant in its use as an etch stopper for technology beyond 7 nm node semiconductor processing. Herein, we explore the correlation between the hydrogen concentration, hydrogen bonding states, bulk film density, residual impurity concentration, and the WERs of PEALD SiNx using Fourier transform infrared spectrometry, X-ray reflectivity, and spectroscopic ellipsometry, etc. PEALD SiNx films for this study were deposited using hexachlorodisilane and hollow cathode plasma source under a range of process temperatures (270 °C – 360 °C) and plasma gas compositions (N2/NH3 or Ar/NH3) to understand the influence of hydrogen concentration, hydrogen bonding states, bulk film density, and residual impurity concentration on the WER. Varying hydrogen concentration and differences in the hydrogen bonding states resulted in different bulk film densities, and accordingly, a variation in WER. We observe a linear relationship between hydrogen bonding concentration and WER as well as a reciprocal relationship between bulk film density and WER. Analogous to the PECVD SiNx processes, a reduction in hydrogen bonding concentration arises from either (1) thermal activation or (2) plasma excited species. However, unlike the case with silane (SiH4)-based PECVD SiNx, PEALD SiNx WERs are affected by residual impurities of Si precursors (i.e., chlorine impurity). Thus, possible wet etching mechanisms in HF in which the WER is affected by hydrogen bonding states or residual impurities are proposed. The shifts of amine basicity in SiNx due to different hydrogen bonding states and the changes in Si electrophilicity due to Cl impurity content are suggested as the main mechanisms that influence WER in the PEALD processes.
关键词： plasma-enhanced ALD (PEALD),bulk film density,hexachlorodisilane (HCDS),wet etch rate (WER),silicon nitride,hydrogen/chlorine content,atomic layer deposition (ALD),hydrogen bonding state
更新于2025-09-23 15:21:01
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Role of reactive gas on the structure and properties of titanium nitride films grown by plasma enhanced atomic layer deposition
摘要： The authors report on the role of various reactive gases on the structure and properties of TiN thin films prepared by plasma enhanced atomic layer deposition (PEALD) from tetrakis(dimethylamido) titanium. The reactive gas plays an important role determining the film structure and properties. Nitrogen-based plasma (N2 and NH3) resulted in low oxygen (~3%) and carbon (~2%) contamination and well-defined columnar grain structure. A nitrogen excess (~4%) was found in the films deposited using N2 plasma. The stoichiometric films and lowest resistivity (~80 μΩ cm) were achieved using NH3 plasma. Deposition using H2 plasma resulted in higher carbon and oxygen contamination (~6% for each element). The reactive gas also plays an important role in determining the grain size and preferential orientation. By varying the plasma chemistry, either (111) or (100) oriented films can be obtained. A mechanism determining the PEALD TiN preferential orientation is proposed. Finally, plasma induced degradation of the underlying dielectric layer is evaluated.
关键词： plasma enhanced atomic layer deposition,film structure,properties,titanium nitride,reactive gases
更新于2025-09-23 15:21:01