Number Of Stacked Layers Research Articles

Investigation and comparative analysis of polysilicon and MoS2-based channels in 3D NAND

Abstract In 3D NAND, channel current sensing deteriorates as the number of stacked layers increases due to the granular nature of the polysilicon channel. Recent studies on 2D materials like MoS2 have demonstrated its exceptional channel material properties, including high mobility and no interfacial dangling bonds. We incorporate MoS2 as the channel material in 3D NAND, demonstrating better cell current and lower subthreshold slope than conventional polysilicon channels to overcome the low channel current in 3D NAND. The scaling performance of the MoS2 channel device shows the gate and spacer lengths can be scaled down to 10 nm without degrading the program and erasing performance. Additionally, MoS2-based channel NAND suppresses WL interference by reducing threshold voltage shifts of the cells adjacent to the program cells. These results show MoS2 as a promising alternative channel material for 3D NAND, offering enhanced bit density growth and overall performance in flash memory applications.

Dynamic kinetic studies of lysozyme removal as protein waste using weak ion exchange nanofiber membranes in flow systems: Linear and nonlinear model analysis

BackgroundThis study explores lysozyme removal using a weak ion exchange nanofiber membrane in a continuous flow system. Understanding removal kinetics is critical for designing, optimizing, and scaling industrial processes. Kinetic models play a crucial role in predicting removal behaviors, including the pseudo-first-order, pseudo-second-order, Elovich, Avrami, and intra-particle diffusion models. Each model provides different insights based on its assumptions, making them suitable for analyzing various removal systems and mechanisms. MethodsThe study investigated the effects of four parameters—removal pH, initial lysozyme concentration, loading flow rate, and the number of membranes stacking layers—on dynamic kinetic binding behavior. Both linear and non-linear kinetic models were employed to analyze experimental results, focusing on removal rates and mechanisms. Significant FindingsAnalysis revealed key insights into removal kinetics. The change in removal pH significantly affected the binding rate and capacity. Higher initial concentrations increased binding rates, while changes in loading flow rate influenced removal rate and capacity. Increasing the number of membrane stacking layers enhanced the removal capacity and increased the pressure drop. These findings underscore the importance of optimizing parameters for efficient removal in biotechnology and wastewater treatment.

Finite element modeling of a piezoelectric actuator coupled to the cochlear round window

Abstract Round window (RW) stimulation is an application of active middle ear implants. However, its clinical outcomes show a substantial degree of variability due to the mismatch of the diameter of the actuator and the RW membrane, and the surgically challenging for placing the actuator. To address this problem, we developed a new piezoelectric actuator for RW stimulation. Firstly, we specifically designed the actuator’s mechanical structure for the RW stimulation. Then, we constructed a finite element (FE) model of the piezoelectric actuator coupled with the human ear’s RW membrane. Using this coupled FE model, we studied the influence of the actuator’s supporting stiffness and the number of piezoelectric stack layers on the stimulated stapes velocity. Finally, we fabricated the piezoelectric actuator and tested its output on human cadaver temporal bones. The results show that the developed piezoelectric actuator has the advantages of a wide operating frequency range and controlled preload on the RW membrane.

Tailored graphene nanoparticles for biomedical application: preliminary in vitro characterization of the functionality in model cell lines

Thanks to an environmentally friendly physical treatment of high purity graphite, a good control of the structure of graphene nanoparticles (GNPs) has been obtained with the production of stable and reproducible GNPs water dispersions. The preparation protocol entailed ball-milling of synthetic graphite followed by sonication in water and centrifugation/separation procedures. This way, two different GNPs samples with slightly different structural characteristics were harvested: TOP60, showing an average lateral size of the graphene layers <L> = 70 nm and average number of stacked layers <N> = 4, and BOTTOM60, with <L> = 120 nm and <N> = 6. A detailed structural characterization of GNPs was performed as mandatory pre-requisite to build reliable structure/properties correlations, in terms of both biomedical efficacy and toxicity, aiming at a rationale design of tailored materials for applications in biological environments.To this end, in this study GNPs were thoroughly characterized, focusing on cytotoxicity, cellular uptake, and inflammatory response, by testing their effect in different cell lines. BOTTOM60 GNPs in culture medium and in the presence of cells showed a tendency to form big aggregates, phenomenon that was probably responsible for their cytotoxicity at high concentrations. On the other hand, TOP60 GNPs showed a diverse behavior depending on the cell type under investigation. Indeed, the nanoparticles were internalized by cells specialized in endo/phagocytosis, such as astrocytoma cells, but not by carcinoma cells of epithelial origin. Moreover, TOP60 GNPs caused a reduction of proliferation only at high concentration and did not trigger an inflammatory response in THP-1-derived macrophages.The evidence here collected paves the way for further investigations towards the development of GNPs-based drug delivery systems.

Hydrodesulfurization and isomerization performance of model FCC naphtha over sulfided Co(Ni)–Mo/Y catalysts

The process of deep hydrodesulfurization (HDS) in gasoline typically results in the saturation of olefins, leading to significant reductions in octane number. In this work, Y-supported Co(Ni)–Mo catalysts that with different Ni–Co content were prepared by the incipient wetness impregnation method, the structure and properties were characterized and analyzed using HRTEM, XPS, H2-TPR, and NH3-TPD. The isomerization of 1-hexene and 1-octene as well as the HDS of thiophene were studied by using model FCC naphtha. The incorporation of Ni was found to enhance the number of MoS2 stacking layers, thereby improving the degree of sulfurization in Mo and subsequently increasing the desulfurization rate, with a maximum achieved desulfurization rate of 94.7%. When employing a Ni/Co ratio of 3:2, optimal synergy between Ni and Co is achieved, resulting in a greater presence of multi-layer stacked II-Co(Ni)MoS active phases. Additionally, appropriate Brønsted acidity levels are maintained to facilitate efficient olefin isomerization while preserving high HDS activity. As a result, the current isomerization yield stands at 58.2%(mass). These understandings shed light on the development of highly HDS and olefin isomerization catalysts.

Measuring linear birefringence via rotating-sample transmission Stokes spectropolarimetry

Linear birefringence is a fundamental property of optically anisotropic media, defined by the difference in refractive index experienced by light polarized along orthogonal directions. It is usually manifested in microscopically aligned molecular systems, where a preferential direction of light–matter interaction is created. For instance, the anisotropic structure of calcite crystal causes the famous double-refraction phenomenon. Another common example is commercial adhesive tapes, which are polymeric materials possessing birefringent properties due to their manufacturing processes. The intrinsic relation between birefringence and molecular alignment forges a new analytical route to study materials such as polymeric thin films. Therefore, the capacity of measuring linear birefringence and its fast axis is of paramount importance for the science of anisotropic molecular systems. In this contribution, a comprehensive approach to acquire linear birefringence using rotating-sample transmission Stokes spectropolarimetry is presented and applied to transparent adhesive tapes as a case study. The experimental setup comprises a thermal light source and a spectropolarimeter capable of determining wavelength distributions of Stokes parameters. The samples are carefully aligned in a rotating mount and subjected to a fixed broadband vertically polarized light beam. Then, the transmitted light is analyzed using a rotating retarder type of spectropolarimeter. Through systematic variation of the sample’s angular position, the Stokes parameters of transmitted light are measured for each transmitted wavelength as a function of the sample’s angular position. The linear retardance and fast axis direction relative to the tape’s long axis are then determined from the modulation of Stokes parameters over sample rotation. The model derivation, experimental procedure, and signal processing protocol are described in detail, and the approach is verified with a simple correlation between linear retardance and the number of stacked layers of tape.

Crack characteristics of pulsed laser brazed diamond grinding wheel

Experiments on pulsed laser brazing of diamond grinding wheels were carried out in this paper. The crack characteristics and residual stress of brazed layer were detected and evaluated. The influence laws of pulse width, frequency, diamond mixing ratio, number of stacked layers, powder thickness and preheating temperature on crack characteristics were investigated. The pulsed laser characteristic coefficients (peak pulse power density/pulse interval time) and the correlation law between thermal stresses and cracks are discussed. The results show that the pulse width and frequency of the pulsed laser affect the cracking rate by varying the energy input and the time between pulses. The existence of a suitable value for the pulse characteristic coefficient corresponding to pulse width and frequency corresponds to a lower cracking rate. Thermal stress variations due to changes in process conditions at different diamond percentages, number of stacked layers, and preheating temperatures are the main causes of crack rate variations. Cracking is not only affected by thermal stresses, but also by the quality of the formed surface when pulsed laser brazing diamond to nickel–chromium alloy brazing material. For example, the main reason for the variation in cracking rate is the change in the morphology of the molded surface due to the variation in the thickness of the powder spread at different variations in the thickness of the powder spread.

Application of High‐ and Low‐Reactivity Cokes in Hydrogen‐Rich Blast Furnaces

The effects of two cokes with different reactivity on the lump ore's metallurgical properties and coke's solution loss are investigated under the high‐temperature load reduction. The work used an improved test device for softening‐melting and dropping characteristics of iron ores in both CO2 and CO2H2O atmospheres. The deterioration behavior of highly reactive cokes is expounded under hydrogen‐rich conditions. High‐reactivity cokes under hydrogen‐rich conditions are more favorable for enhancing the breathability of charge and the penetration of the coke layer. However, it increased the thickness of the softening zone. High‐reactivity cokes had obvious internal and external reaction gradients. The solution loss reaction mostly occurred on the surface, with selectivity. The longitudinal stacking height, layer number, and order degree in the carbon structure decreases after the reaction. The carbon‐structure difference weakens between the shell and core. The enhancement of coke's reactivity, however, results in the significant loss of coke powders on its surface. Unreduced FeO and refractory Fe2SiO4 are more likely to appear in the droplets, which is not conducive to the reduction of Fe and the generation of slag crust in the furnace. The difficulty in separating lump ores and cokes is aggravated, and more iron‐containing charge remain in the furnace.

Numerical analysis of stacked HTS tapes in rotating magnetic fields using H and T-A formulations

Superconducting windings in rotating electrical machines and multi-phase transformers are subject to rotating magnetic fields. Most existing studies on the electromagnetic characteristics of stacked high-temperature superconducting (HTS) tapes focus on the influence of vertical magnetic field (VMF) and the transport current. The numerical study on characteristics of HTS stacked tapes in rotating magnetic fields (RMFs) has received less research attention. This paper presents two-dimensional models of stacked HTS tapes in RMF based on H and T-A formulations. AC losses obtained by the two formulations agree well in a single tape configuration but significantly differ in a stack configuration. The discrepancy increases as the number of stack layers and the stack interval increase. Under the same magnetic field amplitude, the RMF penetration depth in stacked tapes is higher than those of VMF and parallel magnetic field (PMF), and the parallel component of RMF causes higher AC loss in the end tapes of a stack. While the applied current increases the overall AC loss, it can significantly decrease the AC loss of the end tape. It is found that reducing the stack interval and replacing end tapes with tapes of higher critical current can significantly reduce the overall AC loss of stacked tapes in an RMF. These results are crucial for modeling superconducting machines and offer valuable insights into characterizing superconducting tapes in RMFs using numerical methods.

Rational design of titanium-doped Y zeolite for hydrodenitrogenation of aromatic N-heterocyclic compounds

Ti modified Y zeolites with different Ti content were synthesized by in-situ hydrothermal crystallization method and used as the support of hydrodenitrogenation (HDN) catalyst. The forms of Ti species in the zeolites and the effect of Ti incorporation on the active metal states of the corresponding catalysts were investigated by XRD, UV–Vis DRS, XPS, HAADF-STEM, ICP-OES, Py-FTIR, H2-TPR, HRTEM, and DFT calculation. The results show that the incorporation of in-situ Ti species into Y zeolite led to a decrease in the Brønsted acid sites (BAS) /Lewis acid sites (LAS) value of the corresponding catalyst, but effectively enhanced the stacking layer number of the WS2 active phase by weakening the interaction between the active metals and the supports, which is manifested in the improvement of the hydrogenolysis activity and the decrease of the hydrogenation activity of the catalyst. When the hydrogenolysis activity and hydrogenation activity in the catalyst match to a certain extent, that is, the BAS/LAS value and the stacking layer number of the active phase reach an appropriate value, the HDN catalyst exhibited the highest catalytic activity. The NiW/Y-0.1Ti catalyst with suitable amount of BAS and stacking layer number of active phase showed the maximum kHDN values (11.7 × 10-4 mol·g−1·h−1 and 3.9 × 10-4 mol·g−1·h−1) and TOFs (1.91 h−1 and 1.04 h−1) of quinoline and indole HDN.

Modular multilayered PVC gel soft actuators for novel lightweight humanoid facial robot

Electroactive multilayered poly (vinyl chloride) (PVC) gel actuators (MPGAs) have attracted increasing interest in the field of soft robotics. However, they still face problems such as relatively low contraction strain, poor durability, and robustness. Herein, we report a new modular multilayered PVC gel actuator (M-MPGA) based on stainless steel meshed electrodes. The output characteristics of the actuator were notably improved by adjusting the plasticizer content in the gel and optimizing the structural parameters of the meshed anode electrodes. The effect of the number of stacked layers on the performance of the actuator was investigated and a dynamic model was derived for the actuator modular design. Actuator modules with multidirectional degrees of actuation were established and applied to a humanoid facial robot for the first time. The developed actuator with a meshed electrode size of #60 was found to exhibit a high contraction strain of over 20 %, which is almost twice that of the traditional MPGAs with an electrode size of #100. In addition, the fabricated actuator module had a low loss rate (1.152 %), high operating bandwidth (9.7 Hz), fast response (∼45 ms), and exceptional stability (95.24 % retention at 10,000 s actuation) without any distortion of the actuation performance. Furthermore, the developed prototype humanoid facial robot demonstrated the advantages of ultralight weight (754 g), smooth facial expression, and ease of control.

Controllable Regulation of MoS2 Surface Atomic Exposure for Boosting Interfacial Polarization and Microwave Absorption

AbstractAtomic‐level surface design of 2D materials, which benefits from their ultra‐high occupancy of surface atoms, has demonstrated significant potential for regulating electronic states. Despite efforts to explore heterojunctions on 2D surfaces, the stacking‐dominated surface electronic structures and their influences on dielectric polarization remain unclear. Herein, a confined growth strategy is proposed to accurately adjust the surface atom occupancy of MoS2 nanoflakes and thereby boost the polarization‐dominated microwave absorption (MA). By altering the stacking layer number from single layers to tens of layers of MoS2, the charge transfer from graphite substrate to MoS2 surface atoms, accompanied by the formation of local electric fields, reaches its highest intensity at two layers and then degrades dramatically with thicker MoS2 nanoflakes. The strengthened dielectric properties eventually enhance the MA performance, increasing the maximum absorption intensity (41.9 dB) by 346% and the effective absorption bandwidth (3 GHz) by 750%. These discoveries shed new light on the electronic modification of 2D materials and their electromagnetic functionalization.

Few-layered-graphene - Si3N4 composite powders prepared by decomposition of methane onto a Si3N4 powder bed: Control of the average number of layers in the graphene stack

The chemical vapor deposition of carbon is performed onto a commercial silicon nitride powder bed. This produces few-layered-graphene (FLG) films or islands on the Si3N4 particles. The samples are characterized by several techniques including Raman spectroscopy, scanning and transmission electron microscopy. The experimental parameters of the methane (CH4) decomposition (temperature, CH4 concentration, dwell time) are correlated to the average number of graphene layers (N). Complete coverage of the Si3N4 particles is achieved for FLG with N controlled in the range 5–12, corresponding to 4–12 wt%. of carbon. Below that, for stacks with N = 3–4, the coverage of the surface by FLG islands is not total. The value found for the activation energy of CH4 conversion into carbon shows that island-growth is favored over layer-growth. A macroscopical method based on a carbon proportion evaluation gives an approximation of both the coverage ratio and the average number of layers in the stack.

Rock lithology classification algorithm based on improved self-attention mechanism VIT

Abstract When applying VIT to image classification, although good accuracy has been achieved, there is a limitation on the number of stacked layers. The similarity between different tokens increases as the model deepens, leading to low accuracy in shallow VIT models and wasting computational resources in deep VIT models. To address this issue, a multi-valued self-attention mechanism is proposed. By introducing an additional clue “V,” that does not vary arbitrarily, the dot product similarity observes each position in the token sequence more, reducing the depth of the attention mechanism network and avoiding the problem of similarity disappearing between deep tokens. Additionally, the loss function is improved by combining the Focal Loss function with Label Smoothing, enhancing the model’s handling of uncertain images while retaining the category focus of Focal Loss. Experiments are conducted on a rock lithology classification dataset, showing that compared to the VGG model and ResNet-18, the accuracy of the ResNet-50 model improves by 17.6%, 12%, and 4.9%, respectively. This paper also demonstrates the effectiveness of the multi-valued self-attention mechanism, which significantly reduces depth and parameter count while maintaining comparable accuracy. Finally, generalization experiments on the CIFAR-10 dataset further validate these conclusions.

Evolution of macromolecular structure during coal oxidation via FTIR, XRD and Raman

The analysis of the macromolecular structure and morphology in coal during oxidation is the basis to explore the mechanism of spontaneous combustion. To explore the evolutionary rules of coal macromolecular structure during oxidation, Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), and Raman Spectroscopy (Raman) were employed to analyze the coal samples with different oxidation degrees. The results revealed that the oxidation action led to the decrease of the aliphatic structures and aromatic hydroxyl groups in coal, while promoting the formation of oxygen-containing functional groups and aromatic structures. It also led to a relative increase of free hydroxyl groups linked to hydrogen bonds. The aromatic layer spacing (d002) decreased with increasing oxidation degree, while the microcrystal stacking height (Lc), the aromatic layer diameter (La), the average number of crystal stacking layers (n) generally increased. It indicated that small aromatic ring molecules in coal could undergo continuous polymerization during oxidation to form a single aromatic layer structure. The variation of Raman spectrum parameters exhibited a consistent decreasing trend in WD/WG, ID/IG, AD/AG, and A(GR+SL)/AG value, indicating an increase in the vibration of sp2 hybridization carbon atoms within the lattice structure of coal. Conversely, PG-D, AS/AD and A(GR+VL+VR)/AD value increased overall, suggesting that small aromatic rings decreased in content during oxidation while polymerizing into larger aromatic rings. The coal structure underwent a brief stage of disordered evolution during oxidation, followed by removal of impurity structures and condensation of aromatic structures due to increasing oxidation temperatures, ultimately leading to a highly ordered crystalline state. The oxidation process significantly influenced the development of coal's aromatic structure, particularly in less metamorphic coal. The research findings provide a theoretical basis for analyzing the underlying mechanism behind spontaneous combustion induced by coal oxidation.

Layer-Dependent Quantum Anomalous Hall and Quantum Spin Hall Effects in Two-Dimensional LiFeTe.

The emergence of an intrinsic quantum anomalous Hall (QAH) insulator with long-range magnetic order triggers unprecedented prosperity for combining topology and magnetism in low dimensions. Here, based on stacked two-dimensional LiFeTe, we confirm that magnetic coupling and topological electronic states can be simultaneously manipulated by just changing the layer numbers. Monolayer LiFeTe shows intralayer ferrimagnetic coupling, behaving as a QAH insulator with Chern number C = 2. Beyond the monolayer, the odd and even layers of LiFeTe correspond to uncompensated and compensated interlayer antiferromagnets, resulting in unexpected QAH and quantum spin Hall (QSH) states, respectively. Moreover, the spin Chern number is proportional to the stacking layer numbers in even-layer LiFeTe, proving that the spin Hall conductivity can be continuously enhanced by increasing layer numbers. Therefore, the odd-even-layer-dependent QAH and QSH effects found in LiFeTe topological insulators offer new insight into regulating quantum states in two-dimensional topological materials.

Phase-wise attention GCN for recommendation denoising

In recent years, Graph Convolution Network (GCN) has been widely applied in recommendation systems. Compared to traditional collaborative filtering methods that only aggregate information of neighboring nodes, GCN-based recommendation systems can aggregate information of high-order neighborhoods of a node to achieve better performance. However, GCN-based recommendation systems have faced the over-smoothing problem. The over-smoothing problem causes the performance of recommender systems first to rise and then decrease as the number of stacked layers increases. Previous GCN-based recommender systems have provided a few solutions to over-smoothing. We believe that there are still two problems: (1) most models focus on aggregating diverse information, with less consideration of filtering noise; (2) most models ignore the fact that there are differences in different stages of the process of aggregating information using GCN. We introduce a Phase-wise Attention mechanism to address these issues and propose a Phase-wise Attention GCN (PAGCN) recommendation model. Considering the different characteristics of different stages during the aggregation process of the GCN-based recommendation systems, our model uses different information aggregation methods in different graph convolution layers and adopts targeted aggregation methods. In this way, high-order neighborhood information can be more controlled to improve the performance and effectiveness of our model. The experimental results on real-world datasets show that our model outperforms various baselines, demonstrating the reasonableness of our method.

Near-infrared Spectroscopy for Remote Sensing of Porosity, Density, and Cubicity of Crystalline and Amorphous H2O Ices in Astrophysical Environments

We present laboratory spectra of pure amorphous and crystalline H2O ices in the near-infrared (NIR, 1–2.5 μm/10,000–4000 cm−1) at 80–180 K. The aim of this study is to provide spectroscopic reference data that allow remotely accessing ice properties for icy objects such as icy moons, cometary ice, or Saturn rings. Specifically, we identify new spectral markers for assessing three important properties of ices in space: (i) porosity/fluffiness, (ii) bulk density of amorphous ice, and (iii) cubicity in crystalline ice. The analysis is based on the first OH-stretching overtone (2ν OH) and the combinational band at 5000 cm−1/2 μm, which are potent spectral markers for these properties. By comparison of vapor-deposited, microporous amorphous solid water, pore-free low-, high-, and very-high-density amorphous ice, we are able to separate the effect of (bulk) density from the effect of porosity on NIR-spectra of amorphous ices. This allows for clarifying a longstanding inconsistency about the density of amorphous ice vapor-deposited at low temperatures, first brought up by Jenniskens & Blake. Direct comparison of NIR spectra with powder X-ray diffractograms allows us to correlate spectral features with the number of cubic stacking layers in stacking-disordered ice Isd, ranging from fully cubic ice Ic to fully hexagonal ice Ih. We show that exposure times for instruments on the James Webb Space Telescope are in the hour range to distinguish these properties, demonstrating the usefulness of the neglected NIR spectral range for identifying ices in space.

Crystalline-topologies engineering of bio-spore-derived hard carbon for efficient low-potential potassium ion storage

Clarifying the relationship between crystalline topologies of hard carbon and electrochemical K+ storage behaviors is essential to develop low-cost anode for K+ battery. Herein, bio-mass derived hard carbons with various crystalline topologies were synthesized for the first time by one-step pyrolysis of spores of sorghum smut fungus as new precursors. The crystalline-structures of spore-derived hard carbons including graphitic-like layer number, spacing and curvature can be effectively modulated by pyrolysis temperatures, leading to significant difference between correspondingly as-synthesized hard carbons for K+ storage. The hard carbon obtained at 1400 °C presents a unique crystalline structure with fewer graphite stacking layers down to 2, achieving the excellent K+ storage performance, in which, it presents a high capacity of 495.0 mAh/g with a significant plateau capacity of 368.9 mAh/g (< 0.5 V), a good rate performance of 175.0 mAh g-1 at 500 mA g-1 and stable cycling performance (125.0 mAh g-1 at 500 mA g-1 over 600 cycles), outperforming the most of reported hard carbons derived from various precursors. Meanwhile, the DFT calculation further clarifies that the crystalline topologies of hard carbon play a critical role for efficient K+ storage. In particular, there is an interesting discovery that the number of graphite stacking layers can significantly affect the migration and diffusion of K+, in which, the fewer the number of graphite stacking layers, the lower the energy barrier of K+ diffusion between graphite layers. These results in the work provide new insights for the understanding of K+ storage behavior in hard carbon.

Improvement of warpage and leakage for 3D NAND flash memory

GLS (Gate line split) filling is a very important process in 3D NAND flash memory (3D NAND) fabrication. Filling materials in the GLS should have threefold properties, such as warpage tunability, leakage-free and low resistance. In this paper, the effects of different GLS filling materials (SiO2, W, amorphous silicon: A-Si) on F-attack, warpage and resistance were studied. GLS filled with A-Si shows best performance on warpage and F-attack. For 3D NAND, the number of stacked layers is predicted as a function of the wafer warpage, and the wafer warpage difference between GLS filled with A-Si and W was compared. With the same number of stacking layers, the wafer warpage post GLS filled with A-Si is smaller than that filled with W. Meanwhile, A-Si is produced by the decomposition of SiH4 by low pressure chemical vapor deposition (LPCVD) process, F-related by-product in the GLS filling material and consequent ACS (array common source) to WL (Word line) leakage by F-attack are avoided. A-Si is the best choice for GLS filling. This work provides an efficient method to solve the warpage and leakage problem in 3D NAND flash memory fabrication.