Effective parameters on diameter of carbon nanotubes by plasma enhanced chemical vapor deposition

The effective parameters on the diameter of carbon nanotubes (CNTs) by plasma enhanced chemical vapor deposition (PECVD) were presented.Among lots of influential parameters,the effects of the catalytic film thickness and the pretreatment plasma power on the growth of CNTs were investigated.The results show that the size of catalytic islands increases by increasing the thickness of catalytic layer,but the density of CNTs decreases.The pretreatment duration time of 30 s is the optimal condition for growing CNTs with about 50 nm in diameter.By increasing the pretreatment plasma power,the diameter of CNTs decreases gradually.However,the diameter of CNTs does not change drastically from 80 to 120 W.The uniformly grown CNTs with the diameter of 50 nm are obtained at the pretreatment plasma power of 100 W.

Microstructure evolution and mechanical properties of Ti-B-N coatings deposited by plasma-enhanced chemical vapor deposition

Ternary Ti-B-N coatings were synthesized on AISI 304 and Si wafer by plasma-enhanced chemical vapor deposition (PECVD) technique using a gaseous mixture of TiCl4,BCl3,H2,N2,and Ar.By virtue of X-ray diffraction analysis,X-ray photoelectron spectroscopy,scanning electron microscope,and high-resolution transmission electron microscope,the influences of B content on the microstructure and properties of Ti B N coatings were investigated systematically.The results indicated that the microstructure and mechanical properties of Ti-B-N coatings largely depend on the transformation from FCC-TiN phase to HCP-TiB2 phase.With increasing B content and decreasing N content in the coatings,the coating microstructure evolves gradually from FCC-TiN/a-BN to HCP-TiB2 /a-BN via FCC-TiN+HCP-TiB2/a-BN.The highest microhardness of about 34 GPa is achieved,which corresponds to the nanocomposite Ti-63%B-N (mole fraction) coating consisting of the HCP-TiB2 nano-crystallites and amorphous BN phase.The lowest friction-coefficient was observed for the nanocomposite Ti-41%B-N (mole fraction) coating consisting of the FCC-TiN nanocrystallites and amorphous BN

Characteristics and Electrical Properties of SiNx:H Films Fabricated by Plasma-Enhanced Chemical Vapor Deposition

SiNx：H films with different N/Si ratios are synthesized by plasma-enhanced chemical vapor deposition （PECVD）. Composition and structure characteristics are detected by Fourier transform infrared spectroscopy （FTIR） and X-ray photoelectron spectroscopy （XPS）. It indicates that Si-N bonds increase with increased NH3/SiH4 ratio. Electrical property investigations by I-V measurements show that the prepared films offer higher resistivity and less leakage current with increased N/Si ratio and exhibit entirely insulating properties when N/Si ratio reaches 0.9, which is ascribed to increased Si-N bonds achieved.

Li–N dual-doped ZnO thin films prepared by an ion beam enhanced deposition method

Li-N dual-doped ZnO films [ZnO：（Li,N）] with Li doping concentrations of 3 at.%-5 at.% were grown on a glass substrate using an ion beam enhanced deposition （IBED） method. An optimal p-type ZnO：（Li,N） film with the resistivity of 11.4 Ω·cm was obtained by doping 4 at.% of Li and 5 sccm flow ratio of N2. The ZnO：（Li,N） films-exhibited a wurtzite structure and good transmittance in the visible region. The p-type conductive mechanism of ZnO：（Li,N） films are attributed to the Li substitute Zn site （Lizn） acceptor. N doping in ZnO can forms the Lii-No complex, which depresses the compensation of Li occupy interstitial site （Lii） donors for Lizn acceptor and helps to achieve p-type ZnO：（Li,N） films. Room temperature photoluminescence measurements indicate that the UV peak （381 nm） is due to the shallow acceptors Lizn in the p-type ZnO：（Li,N） films. The band gap of the ZnO：（Li,N） films has a red-shift after p-type doping.

Catalyst Enhanced Chemical Vapor Depositionof Nickel on Polymer Surface

Catalyst enhanced chemical vapor deposition of nickel film on high Tg polymers such as teflon(PTFE), polyimide(PI), and polysulfone(PS) was investigated by hot wall and cold wall CVD, in which Ni(dmg)_2, Ni(acac)_2, Ni(hfac)_2, Ni(TMHD)_2, and Ni(cp)_2 are used as precursors, and palladium complexes are used as catalysts. The films obtained were shiny with silvery color. The Ni was metallic and the purity of Ni was about 92%-95% from XPS analysis. SEM micrographs show that the film had good morphology. The conductivity of the film was about 0.5-4 W·cm^(-1). Ni films had good adhesion with polyimide and polysulfone.

PREPARATION OF TiN FILMS BY N_2 ASSISTED Xe^+ ION BEAM ENHANCED DEPOSITION AND THEIR MECHANICAL PROPERTIES

A new method for preparation of hard TiN films has been developed by using electron beam evaporation-deposition of Ti and bombardment with 40 keV Xe^+ ion beam in a N_2 gas environment.The synthesized TiN films were superior to PVD and CVD ones in respects of improved adhesion to substrate and low preparing temperature.They exhibited good wear resistance and high hardness up to 2200 kg/mm^2.Some industrial applications have been reported.

Influence of ignition condition on the growth of silicon thin films using plasma enhanced chemical vapour deposition

The influences of the plasma ignition condition in plasma enhanced chemical vapour deposition （PECVD） on the interfaces and the microstructures of hydrogenated microcrystalline Si （μc-Si：H） thin films are investigated. The plasma ignition condition is modified by varying the ratio of Sill4 to H2 （RH）. For plasma ignited with a constant gas ratio, the time-resolved optical emission spectroscopy presents a low value of the emission intensity ratio of Ha to Sill＊ （Iuα//SiH＊） at the initial stage, which leads to a thick amorphous incubation layer. For the ignition condition with a profiling RH, the higher IHα/ISiH＊ values are realized. By optimizing the RN modulation, a uniform crystallinity along the growth direction and a denser αc-Si：H film can be obtained. However, an excessively high IRα/ISIH＊ may damage the interface properties, which is indicated by capacitance-voltage （C-V） measurements. Well controlling the ignition condition is critically important for the applications of Si thin films.

SYNTHESIS OF TiN FILM WITH ION BEAM ENHANCED DEPOSITION AND ITS PROPERTIES

The TiN films were synthesized with an alternate process of depositing titanium from a E-gun evaporation source and 40 keV N^+ bombarding onto the target.It is shown from the composi- tion analysis and structure investigations using RBS,AES,TEM,XPS and X-ray diffraction spectrum that the formed fihns are mainly composed of TiN phase with grain size of 30—40 nm and without preferred orientation,the nitrogen content in the film is much less than that in case without N^+ bombarding,and an intermixed region about 40 nm thick exists between the film and the substrate.The films exhibt high microhardness and low friction. ZHOU Jiankun,Ion Beam Laboratory,Shanghai Institute of Metallurgy,Academia Sinica, Shanghai 200050,China

Study on Blood Compatibility of Carbon-Nitride Film Synthesized by Ion Beam Enhanced Deposition

In this paper, blood compatibility of carbonnitride film synthesized by ion beam enhanced deposition is studied. Clotting time measurement, platelet adhesion test and surface energy determination were performed to evaluate the interaction between blood and material. The results show that carbonnitride film has better blood compatibility than titanium, and may be promising in biomaterial filed.

Structural evolution and optical characterization in argon diluted Si:H thin films obtained by plasma enhanced chemical vapor deposition

The structural evolution and optical characterization of hydrogenated silicon(Si:H) thin films obtained by conventional radio frequency(RF) plasma enhanced chemical vapor deposition(PECVD) through decomposition of silane diluted with argon were studied by X-ray diffractometry(XRD),Fourier transform infrared(FTIR) spectroscopy,Raman spectroscopy,transmission electron microscopy(TEM),and ultraviolet and visible(UV-vis) spectroscopy,respectively.The influence of argon dilution on the optical properties of the thin films was also studied.It is found that argon as dilution gas plays a significant role in the growth of nano-crystal grains and amorphous network in Si:H thin films.The structural evolution of the thin films with different argon dilution ratios is observed and it is suggested that argon plasma leads to the nanocrystallization in the thin films during the deposition process.The nanocrystallization initiating at a relatively low dilution ratio is also observed.With the increase of argon portion in the mixed precursor gases,nano-crystal grains in the thin films evolve regularly.The structural evolution is explained by a proposed model based on the energy exchange between the argon plasma constituted with Ar* and Ar+ radicals and the growth regions of the thin films.It is observed that both the absorption of UV-vis light and the optical gap decrease with the increase of dilution ratio.

Plasma-Enhanced Atomic Layer Deposition of Amorphous Ga_(2)O_(3) for Solar-Blind Photodetection

Wide-bandgap gallium oxide(Ga_(2)O_(3))is one of the most promising semiconductor materials for solar-blind(200 nm to 280 nm)photodetection.In its amorphous form,amorphous gallium oxide(a-Ga_(2)O_(3))maintains its intrinsic optoelectronic properties while can be prepared at a low growth temperature,thus it is compatible with Si integrated circuits(ICs)technology.Herein,the a-Ga_(2)O_(3) film is directly deposited on pre-fabricated Au interdigital electrodes by plasma enhanced atomic layer deposition(PE-ALD)at a growth temperature of 250°C.The stoichiometric a-Ga_(2)O_(3) thin film with a low defect density is achieved owing to the mild PE-ALD condition.As a result,the fabricated Au/a-Ga_(2)O_(3)/Au photodetector shows a fast time response,high responsivity,and excellent wavelength selectivity for solar-blind photodetection.Furthermore,an ultra-thin MgO layer is deposited by PE-ALD to passivate the Au/a-Ga_(2)O_(3)/Au interface,resulting in the responsivity of 788 A/W(under 254 nm at 10 V),a 250-nm-to-400-nm rejection ratio of 9.2×10^(3),and the rise time and the decay time of 32 ms and 6 ms,respectively.These results demonstrate that the a-Ga_(2)O_(3) film grown by PE-ALD is a promising candidate for high-performance solar-blind photodetection and potentially can be integrated with Si ICs for commercial production.

Influence of oxygen on the growth of cubic boron nitride thin films by plasma-enhanced chemical vapour deposition

Cubic boron nitride thin films were deposited on silicon substrates by low-pressure inductively coupled plasmaenhanced chemical vapour deposition. It was found that the introduction of 02 into the deposition system suppresses both nucleation and growth of cubic boron nitride. At a B2H6 concentration of 2.5% during film deposition, the critical O2 concentration allowed for the nucleation of cubic boron nitride was found to be less than 1.4%, while that for the growth of cubic boron nitride was higher than 2.1%. Moreover, the infrared absorption peak observed at around 1230- 1280 cm^-1, frequently detected for cubic boron nitride films prepared using non-ultrahigh vacuum systems, appears to be due to the absorption of boron oxide, a contaminant formed as a result of the oxygen impurity. Therefore, the existence of trace oxygen contamination in boron nitride films can be evaluated qualitatively by this infrared absorption peak.

Formation and Characterization of Pd,Pt and Pd-Pt Alloy Films on Polyimide by Catalyst-Enhanced Chemical Vapor Deposition

Platinum, palladium and their alloy films on polyimide were formed by catalyst-enhanced chemical vapor deposition （CVD） in the carrier gas （N2, O2） at 220-300℃ under reduced pressure and normal pressure. The deposition of palladium complexes [ Pd（（η3-allyl）（hfac） and Pd（hfac）2 ] gives pure palladium film, while the deposition of platinum needs the enhancement of palladium complex by mixing precursor platinum complex Pt（COD）Me2 and palladium complex in the same chamber. The co-deposition of Pd and Pt metals was used for the deposition of alloy films. During the CVD of palladium-platinum alloy, the Pd/Pt atomic ratios vary under different co-deposition conditions. These metal films were characterized by XPS and SEM, and show a good adhesive property.

Effect of ion-beam assisted deposition on the film stresses of TiO_2 and SiO_2 and stress control

Based on Hartmann-Shack sensor technique, an online thin film stress measuring system was introduced to measure the film stresses of TiO2 and SiO2, and comparison was made between the film stresses prepared respectively by the conventional process and the ion-beam assisted deposition. The effect of ion-beam assisted deposition on the film stresses of TiO2 and SiO2 was investigated in details, and the stress control methodologies using on-line adjustment and film doping were put forward. The results show that the film stress value of TiO2 prepared by ion-beam assisted deposition is 40 MPa lower than that prepared by conventional process, and the stress of TiO2 film changes gradually from tensile stress into compressive stress with increasing ion energy; while the film stress of SiO2 is a tensile stress under ion-beam assisted deposition because of the ion-beam sputtering effect, and the film refractive index decreases with increasing ion energy. A dynamic film stress control can be achieved through in-situ adjustment of the processing parameters based on the online film stress measuring technique, and the intrinsic stress of film can be effectively changed through film doping.

Effects of the ion-beam voltage on the properties of the diamond-like carbon thin film prepared by ion-beam sputtering deposition

Diamond-like carbon （DLC） thin film is one of the most widely used optical thin films. The fraction of chemical bondings has a great influence on the properties of the DLC film. In this work, DLC thin films are prepared by ion-beam sputtering deposition in Ar and CH4 mixtures with graphite as the target. The influences of the ion-beam voltage on the surface morphology, chemical structure, mechanical and infrared optical properties of the DLC films are investigated by atomic force microscopy （AFM）, Raman spectroscopy, nanoindentation, and Fourier transform infrared （FTIR） spec- troscopy, respectively. The results show that the surface of the film is uniform and smooth. The film contains sp2 and sp3 hybridized carbon bondings. The film prepared by lower ion beam voltage has a higher sp3 bonding content. It is found that the hardness of DLC films increases with reducing ion-beam voltage, which can be attributed to an increase in the fraction of sp3 carbon bondings in the DLC film. The optical constants can be obtained by the whole infrared optical spectrum fitting with the transmittance spectrum. The refractive index increases with the decrease of the ion-beam voltage, while the extinction coefficient decreases.

Chemical Structure of Carbon Nitride Films Prepared by MW-ECR Plasma Enhanced Magnetron Sputtering

Amorphous carbon nitride thin films were prepared by plasma-enhanced DC magnetron sputtering using twinned microwave electron cyclotron resonance plasma sources. Chemical structure of deposited films was investigated using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results indicate that the deposition rate is strongly affected by direct current bias, and the films are mainly composed of a single amorphous carbon nitride phase with N/C ratio close to C3N4, and the bonding is predominantly of C^N type.

等离子体增强原子层沉积AlN外延单晶GaN研究

氮化镓(GaN)作为第三代半导体材料,具有较大的禁带宽度,较高的击穿电场强度、电子迁移率、热导系数以及直接带隙等优异特性,被广泛应用于电子器件和光电子器件中。由于与衬底的失配问题,早期工艺制备GaN材料难以获得高质量单晶GaN薄膜。直到采用两步生长法,即先在衬底上低温生长氮化铝(AlN)成核层,再高温生长GaN,才极大地提高了GaN材料的质量。目前用于制备AlN成核层的方法有磁控溅射以及分子束外延等,为了进一步提高GaN晶体质量,本研究提出在两英寸c面蓝宝石衬底上使用等离子体增强原子层沉积(Plasma-enhanced Atomic Layer Deposition,PEALD)方法制备AlN成核层来外延GaN。相比于磁控溅射方法,PEALD方法制备AlN的晶体质量更好;相比于分子束外延方法,PEALD方法的工艺简单、成本低且产量大。沉积AlN的表征结果表明,AlN沉积速率为0.1 nm/cycle,并且AlN薄膜具有随其厚度变化而变化的岛状形貌。外延GaN表征结果表明,当沉积厚度为20.8 nm的AlN时,GaN外延层的表面最平整,均方根粗糙度为0.272 nm,同时具有最好的光学特性以及最低的位错密度。本研究提出了在PEALD制备的AlN上外延单晶GaN的新方法,沉积20.8 nm的AlN有利于外延高质量的GaN薄膜,可以用于制备高电子迁移率晶体管及发光二极管。

等离子体增强原子层沉积二氧化硅对多晶硅的损伤机理及防范工艺研究

文章通过电子束检测(EBI)手段研究了等离子体增强原子层沉积(PEALD) SiO_(2)过程中硅烷基酰胺类前驱体副产物对多晶硅产生不可逆损伤的机理。提出用单胺基硅烷基酰胺替代多胺基硅烷基酰胺作为前驱体,来减轻对多晶硅材料的损伤。在不损伤多晶硅前提下,进一步研究化学位阻较小的单胺基前驱体二异丙胺硅烷(DIPAS)对反应速率的影响。

烧结NdFeB磁体表面Zn-Al/T8超疏水复合涂层的显微组织及耐蚀性

为提升烧结NdFeB磁体的耐蚀性,采用旋涂法和等离子体增强化学气相沉积技术在其表面制备Zn-Al/T8(2-全氟辛基乙基丙烯酸酯)超疏水复合涂层。结果表明,Zn-Al涂层主要由片层状的Zn和Al相组成,厚度大约为28μm。Zn-Al/T8复合涂层的接触角达到151.78°,而滚动角仅为5.13°,说明Zn-Al/T8复合涂层可提供一个超疏水表面。Zn-Al涂层和Zn-Al/T8复合涂层对烧结NdFeB的磁性能均无显著影响。Zn-Al涂层通过牺牲阳极来提高NdFeB磁体的耐蚀性,而Zn-Al/T8复合涂层通过超疏水表面进一步提升耐蚀性。Zn-Al/T8复合涂层较Zn-Al涂层具有更好的耐盐雾性能。Zn-Al/T8超疏水复合涂层是一种非常有前途的烧结NdFeB磁体保护涂层。