Molecular dynamics study of deposition mechanism of cubic boron nitride

We have performed molecular dynamics simulations of bombardment of graphitic boron nitride (gBN) by energetic boron and nitrogen particles in order to examine the roles of ion bombardment in ion/plasma-assisted deposition of cubic boron nitride (cBN) thin films. We have found that the interaction of the energetic particles with gBN creates four-fold coordinated local structures (sp³-formation) inside gBN. We have also found that clusters of sp³-formations are created as a result of successive bombardment, some of which have cBN-like structures. On the basis of these results, we propose an atomic-scale model of cBN nucleation in which successive sp³-formation converts gBN into cBN.     

Influence of substrate direct current bias voltage on microcrystalline silicon growth during radio-frequency magnetron sputtering

Hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared on glass, aluminum-covered glass and Si wafer substrates at various substrate bias voltages (V_sb) between -400 and +50 V, and the influence of V_sb on their structural properties was investigated. The crystallinity (crystalline volume fraction and crystallite size) of the μc-Si:H films deposited on glass remained unchanged with respect to V_sb. For μc-Si:H films deposited on aluminum within the V_sb range of -20 to +50 V, the crystallinity also remained unchanged and showed the same crystallinity as that of the films deposited on glass substrate. However, the crystallinity of the μc-Si:H films deposited on aluminum-covered substrate was reduced as V_sb decreased from -20 to -100 V, and the film at V_sb=-400 V was completely amorphous.     

Applications of fullerene beams in analysis of thin layers

Molecular dynamics computer simulations have been employed to model ejection of particles from Ag{1 1 1} metal substrate and thin benzene overlayer bombarded by fullerene cluster projectiles. The sputtering yields are analyzed depending on the size (from C₂₀ up to C₅₄₀) and the kinetic energy (5-20 keV) of a projectile. It has been found that for clean metal substrate bombarded by 15 keV projectiles the maximum ejection is stimulated by the impact of the C₆₀ cluster. However, the size of the cluster projectile maximizing the yield depends on the kinetic energy of the cluster, shifting towards larger clusters as the impact energy increases. For a thin benzene overlayer, the yield increases monotonically with the size of the cluster within investigated range of fullerene projectiles and kinetic energies.     

Mixed resolution model for C60 cluster bombardment of solid benzene

Molecular dynamics simulations of C₆₀ cluster bombardment have been instrumental in elucidating physical phenomena related to the sputtering process; however, chemical phenomena can also play an important role in C₆₀ cluster bombardment of molecular solids. Therefore, a mixed resolution model of C₆₀ cluster bombardment is being developed, where the reactive zone is represented by an all atom region, and the remaining part of the target is described by a coarse-grained representation. A reactive many body potential describes the interactions among atoms; whereas, pair potentials describe the interactions between coarse-grained beads and between coarse-grained beads and atoms. Solid benzene is used to develop the methodology of blending the potentials. The blending of potentials is evaluated by the differences in the velocities of the pressure waves (generated by the C₆₀ impact) between the all atom benzene, coarse-grained benzene and the mixed resolution benzene systems. Initial testing with 1 keV C₆₀ cluster bombardment simulations show a smooth transition between regions.     

Low-energy He-ion beam modifications the surface properties of biomaterial

In the present work, ultra-high-molecular-weight polyethylene (UHMWPE) films were irradiated with 130 keV He ions. The fluence of the ion beam was ranged from 1 × 10¹² to 1 × 10¹⁶ cm^?2. The chemical, morphological, and crystallite structure changes resulted from the ion bombardment were obtained using different spectroscopic techniques. These techniques were Fourier transform infrared spectrometer, scanning electron microscope, X-ray diffraction, and UV–vis spectrophotometry. The surface free energy for untreated and ion-beam-treated samples was determined by means of contact angle measurements of three different liquids. Our results showed a decrease in the crystallinity of UHMWPE and formation of C=O groups on the polymer surface for modified samples as well. A remarkable shifting in the UV–vis spectra toward lower energy and increase in the optical absorption were observed as the ion fluence increases. Measurements of the contact angle indicate remarkable increase in the surface free energy as a function of ion fluence.     

NaTPB修饰TISFET制作Drug FET的研究

用四苯硼钠(NaTPB)修饰离子敏感效应晶体管(ISFET)制成药物敏感场效应晶体管(DrugFET),具有良好的能斯特响应,斜率为58mV/pC以上,线性范围为1.0×10     

氮离子束轰击对电弧离子镀TiN膜层的作用

电弧离子镀膜层中"大颗粒"的存在,降低了膜层质量,限制了其进一步应用.采用俄罗斯UVN 0.5D2I离子束辅助沉积电弧离子镀设备,对高速钢W18Cr4V上沉积的TiN膜层进行了氮离子束轰击.结果表明:TiN膜层表面"大颗粒"完全消失,凹坑浅而平整,粗糙度降低.膜层中较软的Ti和Ti2N向TiN转变,TiN(111)取向逐渐减弱,而(200)取向逐渐增强.膜层的显微硬度由原来的1 980 HV1N升高到2 310HV1N.     

水布垭页岩风化料长期稳定性试验研究

通过室内强化模拟试验,对水布垭心墙堆石坝页岩风化填料的矿物成分、化学成分、颗粒级配的长期稳定性进行了研究。研究结果表明,风化料的矿物成分和化学成分在工程环境中具有较好的长期稳定性;而级配较不稳定,这主要是由其矿物成分及微观结构特征决定。     

背面Ar~+轰击对n~-沟MOSFET特性的影响

研究了低能量背面 Ar+轰击对 n-沟 MOSFET特性的影响 .用低能量 (5 5 0 e V)氩离子束轰击 n-沟 MOSFET芯片的背面 ,能改善其阈值电压 VT、跨导 gm、沟道电导 gd 和有效迁移率 μeff等参数 .结果表明 ,随着轰击时间的增加 ,阈值电压先减小 ,随后变大 ;而跨导、沟道电导和有效迁移率先增大 ,随后减小 .实验证明 ,上述参数的变化是由于界面态密度和固定电荷密度变化的结果