MOCVD growth of HfSixOy films from hafnium β-diketonato silylamides and siloxides

New hafnium β-diketonato-silylamide and siloxides namely Hf(thd)₂[N(SiMe₃)₂]₂ (1), Hf(thd)₂(OSiMe₃)₂ (2) and Hf(thd)₂(OSi^tBuMe₂)₂ (3) (thd=2,2,6,6-tetramethyl-3,5-heptanedionate) were investigated as single-source precursors for low-pressure pulsed liquid injection MOCVD of HfSi_xO_y thin films on Si(1 0 0) and R-plane sapphire. Films were characterized by XRD, XPS and AFM. The growth rate increased in order 1>2>3 in agreement with the decreasing precursor thermal stability. The activation energy was ∼80-100 kJ/mol. The as-deposited at 550-800 °C films were essentially amorphous; hafnia reflections appeared after 1 h annealing at 900 °C probably due to phase separation into amorphous Si-rich silicate and crystallized HfO₂. The surface of the films showed similar amounts of Hf and Si (∼1:1) and was overstoichiometric in oxygen (ratio O/(Hf+Si) >2). The bulk of the films was Hf-rich (70-85% of Hf/ Hf+Si) and slightly oxygen-deficient. The new complexes are attractive single-source precursors for the deposition of pure and very smooth (R_a∼0.7 nm, <1% relative to thickness) HfSi_xO_y films. Dielectric constant 11.3 and leakage current density 8×10⁻⁴ A/cm² (at −1 V) were measured for a 22 nm thick film.     

节能型复合陶瓷墙地砖的研制与应用

采用新工艺、新技术实现节能减排,开发绿色建材产品已成为新形势下建材行业发的必然选择。通过对陶瓷墙地砖复合生产技术的研究,采用低品位原料生产建筑材料,提供了一个节约优质资源和创意装饰效果的高档瓷质砖生产技术方案。     

Synthesis of CoFe2O4/MWCNTs Nanohybrid and its Effect on the Optical,Thermal, and Conductivity of PVA/CMC Composite as an Application in Electrochemical Devices

Journal of Inorganic and Organometallic Polymers and Materials - The sonochemical approach was used to synthesize of the CoFe2O4/MWCNTs nano-hybrid. The structural characteristics are examined...     

Hybrid 802.11p-cellular architecture for NDN-based VANET

Vehicular network communications (VANET) face multiple challenges due to their intermittent connections and the rapid changes in their topologies. In recent years, several research efforts have explored the use of content-centric approaches to alleviate some of these challenges. One of these promising network designs is Named Data Networking (NDN), which has become a valid solution to support VANET applications. However, in the NDN architecture, the main forwarding mechanism for the interest packets is flooding. This forwarding mechanism will result in excessive collisions, which will lead to the broadcast storm problem. In this paper, we propose VC-NDN: a hybrid and hierarchical Named Data Networking architecture for VANETs. VC-NDN improves content retrieval efficiency through an adapted NDN-based communication model. VC-NDN includes a new interest forwarding scheme to reduce packet collision in the network and an efficient mechanism to support push-based traffic. Furthermore, to reduce communication costs, VC-NDN uses two communication technologies in parallel, namely, IEEE 802.11p and cellular communications, while keeping the usage of the cellular network at a minimum level. Finally, to reduce the impact on vehicle mobility, VC-NDN follows a hierarchical clustering architecture. Specifically, a density-based clustering algorithm is designed to create and maintain stable clusters with multihop communication capability. Our performance study shows that VC-NDN outperforms the basic VNDN solutions in terms of data retrieval delay and packet delivery ratio while minimizing the usage of the cellular network.