Low temperature deposition of tin oxide films by inductively coupled plasma assisted chemical vapor deposition

Well-crystallized tin oxide films were successfully synthesized without additional heating by inductively coupled plasma assisted chemical vapor deposition (ICP-CVD). The degree of crystallization was affected by the ICP power and hydrogen flow rate. The substrate temperature was increased only up to 423-453 K by plasma heating, which suggests that the formation of the SnO₂ crystals was not caused by plasma heating, but by enhanced reactivity of precursors in high density plasma. The micro-hardness of deposited tin oxide films ranged from 5.5 to 11 GPa at different hydrogen flow rates.     

PBII制备TiNx/DLC多层膜的结构及摩擦学性能

采用等离子体基离子注入技术在30CrMnSi钢上制备了TiNx/DLC多层膜，通过X射线光电子谱和激光喇曼光谱测试分析了膜的结构特征，TiNx/DLC膜大气下的摩擦性能和在球盘式摩擦磨损试验机上进行。结果表明：DLC膜的结构强烈依赖于基权脉冲偏压，－5kV制得的DLC膜具有较多的C－H键结构，因而硬度最低，仅有8.3GPa；而-15kV的DLC膜由于含有较多的sp^3键，获得了最高的显微努氏硬度（23.6GPa)。DLC膜与GCr15钢球大气下的摩擦因数为0.17左右，其磨损性能由于TiNx，过渡层引入而显著提高。     

Growth and morphological studies of (100) textured diamond thin films by microwave plasma-enhanced chemical vapor deposition

Textured (100) diamond films have been successfully grown using the plasma-enhanced chemical vapor deposition technique and characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction. The thickness of such a (100)-oriented diamond film can be as thin as 4 μm, and the just-emerged transitional layer is found to be only 1.5 μm, which is very thin compared with the computer simulation value of 700d₀, where d₀ is the average distance between the nuclei. A systematic study of various parameters in the carburization and bias steps on the growth of textured (100) diamond films and the subsequent change of surface morphology has been investigated. Experimental results show that these two pre-growth steps seem to ease the growth of textured (100) diamond films and they should be optimized for a set of growth conditions. It is suggested that varying these parameters in the pre-growth steps may cause a change of microstructure, alignment of nuclei, and defect states in the diamond-like layer, resulting in the morphological change of textured (100) diamond films.     

定向碳纳米管的化学气相沉积制备法

报道了一种简便有效的合成定向碳纳米管 (CNTs)的化学气相沉积 (CVD)制备方法。以铁为催化剂 ,乙炔为碳源 ,采用单一反应炉 ,直接在石英基底上沉积催化剂颗粒薄膜 ,成功合成了定向性好、管径均匀的高质量大密度的碳纳米管     

Rheotaxial diamond growth by chemical vapor deposition

This paper is to report a novel method to synthesize diamond crystal by using a well developed chemical vapor deposition process, but on a liquid substrate, while substrates of prevailing practice are solid. The substrate materials are metals which become liquid at diamond deposition temperature, such as elements Sn and Ga, and eutectic alloys of Cu-Ge, Sn-Ge. One result is that, while reported diamond crystal size was about 10 to 40 micrometers on the solid substrate, on the liquid substrate, the crystal size has reached so far about 300 micrometers. Received: 17 May 2000 / Reviewed and accepted: 8 June 2000     

Texture control of ZnO films by inductively coupled plasma assisted chemical vapor deposition

ZnO films were grown on Si (100) and quartz substrates by inductively coupled plasma-assisted chemical vapor deposition using diethylzinc, O₂, and Ar. ZnO films with the (002) preferred orientation (PO) were formed at substrate temperatures > 250 °C regardless of any other changes made to process variables, since the (002) plane has the lowest formation energy with the highest number of unsaturated Zn-ZnO or O-ZnO bonds. At temperatures < 250 °C, the a-axis plane PO such as (100), (110), and (101) as well as the c-axis (002) plane PO were able to form by varying the temperature, plasma power, and deposition rate. The a-axis PO was formed when the radio frequency power was high enough to produce a crystalline ZnO film but was insufficient to form a (002) PO. The a-axis PO was also formed at higher deposition rates ≥ 20 nm/min when the radio frequency power was high enough to produce crystalline ZnO film. Since the (002) plane grew slowly, the grain exposing (002) plane was overgrown by the grains of the a-axis plane at higher deposition rates.     

High rate deposition of microcrystalline silicon films using jet-type inductively coupled plasma chemical vapor deposition

Microcrystalline silicon (μc-Si) films were deposited at a high rate and low temperature using jet-type inductively coupled plasma chemical vapor deposition (jet-ICPCVD), and the deposition rate, microstructure and electrical properties of the deposited films were investigated. It was demonstrated that a high deposition rate of over 20 nm/s can be achieved while maintaining high crystallinity and low dark conductivity. The deposition rate is well controlled by regulating the generation rate and transport of growth precursors. High crystallinity of the films results principally from hydrogen-induced chemical annealing. Furthermore, the excellent electrical properties benefit from the low oxygen content and/or low deposition temperature.     

Characterization and tribological application of diamond-like carbon (DLC) films prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique

Diamond-like carbon (DLC) films were successfully prepared on glass substrates and surfaces of selenium drums via radio frequency plasma enhanced chemical vapor deposition method. The microstructure, surface morphology, hardness, film adhesion, and tribological properties of the films were characterized and evaluated by X-ray photoelectron spectroscopy, atomic force microscopy, and micro-sclerometer and friction-wear spectrometer. The results showed that DLC films have smooth surfaces, homogeneous particle sizes, and excellent tribological properties, which can be used to improve the surface quality of the selenium drums and prolong their service life.     

Towards controlled synthesis of 2D crystals by chemical vapor deposition (CVD)

The emergence of two-dimensional (2D) materials has captured the imagination of researchers since graphene was first exfoliated from graphite in 2004. Their exotic properties give rise to many exciting potential applications in advanced electronic, optoelectronic, energy and biomedical technologies. Scalable growth of high quality 2D materials is crucial for their adoption in technological applications the same way the arrival of high quality silicon single crystals was to the semiconductor industry. A huge amount of effort has been devoted to grow large-area, highly crystalline 2D crystals such as graphene and transition metal dichalcogenides (TMDs) through various methods. While CVD growth of wafer-scale monolayer graphene and TMDs has been demonstrated, considerable challenges still remain. In this perspective, we advocate for the focus on the crystal growth morphology as an underpinning for understanding, diagnosing and controlling the CVD process and environment for 2D material growth. Like snowflakes in nature, 2D crystals exhibit a rich variety of morphologies under different growth conditions. The mapping of crystal shapes in the growth parameter space “encodes” a wealth of information, the deciphering of which will lead to better understanding of the fundamental growth mechanism and materials properties. To this end, we envision a collective effort by the 2D materials community to establish the correlation between crystal shapes and the intrinsic thermodynamic and kinetic parameters for CVD reactions through integrated crystal growth experiment, database development and machine learning assisted predictive modeling, which will pave a robust path towards controlled synthesis of 2D materials and heterostructures.     

直流热阴极PCVD法间歇生长模式制备金刚石膜

采用直流热阴极PCVD(Plasma chemical vapor deposition)法间歇生长模式制备金刚石膜,通过加入周期性的刻蚀阶段清除金刚石膜在一定生长期中形成的石墨和非晶碳等杂质,实现了金刚石膜生长的质量调控。间歇式生长过程分为沉积阶段和刻蚀阶段,两个阶段交替进行。采用Raman光谱、SEM和XRD对所制金刚石膜的品质进行了表征,并与同样生长条件下连续生长模式制备的金刚石膜样品进行了比较。结果表明,当单个生长周期为30 min(沉积时间为20 min、刻蚀时间为10 min)时,直流热阴极PCVD法间歇生长模式制备的金刚石膜中的非金刚石相杂质含量低于连续间歇生长模式制备的金刚石膜。     

Polycrystalline AlN films with preferential orientation by plasma enhanced chemical vapor deposition

AlN thin films for acoustic wave devices were prepared by Microwave Plasma Enhanced Chemical Vapor Deposition under different process conditions, employing Si (100) and Pt (111)/SiO₂/Si (100) substrates. The films were characterized by X-ray diffraction, Fourier transform infrared transmission spectroscopy, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy. The values of the distance between the plasma and the tri-methyl-aluminum precursor injector, the radiofrequency bias potential, and the substrate temperature were central in the development of polycrystalline films. The choice of the chamber total pressure during deposition allowed for the development of two different crystallographic orientations, i.e., <0001> or <1010>. The film microstructures exhibited in general a column-like growth with rounded tops, an average grain size of about 40 nm, and a surface roughness lower than 20 nm under the best conditions.     

Characterization of MgZnO films grown by plasma enhanced metal-organic chemical vapor deposition

MgZnO (magnesium-zinc-oxide) films were grown on (11-20) sapphire substrates and Zn-polar ZnO substrates by plasma enhanced metal-organic chemical vapor deposition (PE-MOCVD) employing microwave-excited plasma. Structural, electrical and optical properties were investigated by X-ray diffraction, atomic force microscope, Hall, transmittance and photoluminescence measurement. The c-axis lattice constant decreases proportionally to an increase in the Mg content of Mg_xZn_1 − xO films. Therefore, this indicates that Mg atoms can be substituted in the Zn sites. Mg contents in films on ZnO substrates increase up to 0.11. In addition, Ga doped ZnO films were grown on (11-20) sapphire substrates. The resistivity of the films on (11-20) sapphire is controlled between 1.2 × 10^− 3 Ω cm to 1 Ω cm by changing the process conditions. The overall results indicate the promising potential of this PE-MOCVD method for related (Zn, Mg)O films formation because of the reactivity of the radicals, such as oxygen radicals (O?).     

Ultrathin poly(ethylene glycol) monolayers formed by chemical vapor deposition on silicon substrates

Poly(ethylene glycol) (PEG) monolayer was formed through the chemisorption of a vapor phase organosilane. Photochemically cleaned silicon substrate covered with native oxide (SiO2/Si) was exposed to a vapor of an organosilane, that is, 2-(methoxy[polyethyleneoxy]propyl) trimethoxysilane (MPEOPS) for 1-7 h at 150 degrees C. The resulting sample surfaces became relatively hydrophobic showing a static water-contact angle of ca. 67 +/- 2 degrees and their thickness was ellipsometrically measured to be ca. 0.8 +/- 0.1 nm. Atomic force microscopy confirmed that the sample surface was extremely smooth and homogeneous. Isoelectric point of the MPEOPS-monolayer-covered SiO2/Si substrate was measured to be at around pH 4.9, which was close to that of the methoxytri(ethylene glycol)-terminated alkanethiol SAM on gold (pH 4.3). Furthermore, we demonstrated micropatterning of the MPEOPS monolayer based on a direct photolithography using 172 nm VUV light through a photomask. A well-defined microstructure composed of 5 microm x 25 microm rectangular features was successfully fabricated on a MPEOPS monolayer surface. Subsequently treated it by spatially defined CVD treatment using aminosilane molecule, binary microstructures composed of PEG and amino-terminated surfaces were successfully fabricated.     

电子回旋共振-微波等离子体化学气相沉积法制备a-C∶H(N)薄膜

采用电子回旋共振-微波等离子体化学气相沉积技术,使用CH4和N2混合气作为反应气体,在硅衬底上制备掺氮含氢非晶碳(a-C∶H(N))薄膜.紫外Raman光谱证实了薄膜的类金刚石特性;傅立叶变换红外光谱表明薄膜中存在CH和CN键结构.采用原子力显微镜(AFM)观察薄膜的微观表面形貌,结果表明薄膜表面光滑.论文详细叙述了薄膜制备工艺,对测试结果进行了分析讨论,也对这种薄膜在微电子机械系统中的潜在应用进行了探讨.     

Study of plasma enhanced chemical vapor deposition of ZnO films by non-thermal plasma jet at atmospheric pressure

Plasma enhanced chemical vapor deposition using a non-thermal plasma jet was applied to deposition of ZnO films. Using vaporized bis(octane-2,4-dionato)zinc flow crossed by the plasma jet, the deposition rate was as high as several tens of nm/s. From the results of infrared spectra, the films deposited at the substrate temperature T_sub = 100 °C contained a significant amount of carbon residue, while the films prepared at T_sub = 250 °C showed less carbon fraction. The experimental results confirmed that the plasma jet decomposed bis(octane-2,4-dionato)zinc in the gaseous phase and on the substrate, and that there should be the critical T_sub to form high-quality ZnO films in the range from 100 to 250 °C.     

Hard a-SiC:H films formed by remote hydrogen microwave plasma chemical vapor deposition using a novel single-source precursor

The a-SiC:H films were produced by remote hydrogen plasma chemical vapor deposition (RP-CVD) from bis(dimethylsilyl)ethane as a novel single-source precursor. The effect of substrate temperature (T_S) on the kinetics of RP-CVD, chemical composition, structure, surface morphology, and properties of resulting films (density, refractive index, photoluminescence, hardness, elasticity, and resistance to wear) is reported. The T_S dependence of film growth rate implies that RP-CVD is an adsorption controlled process. The increase of T_S from 30 °C to 400 °C causes the elimination of organic moieties from the film and the formation of SiC network structure. The relationships between the relative integrated intensity of SiC IR band and film properties were determined. The films deposited at T_S = 300 °C appear to be very hard materials exhibiting small surface roughness and low intensity of blue photoluminescence (PL). They seem to be suitable protective coatings for metals to increase their wear strength.     

Alumina microtubes prepared via template-directed pulsed chemical vapor deposition (pulsed CVD)

Bundles of alumina microtubes were prepared by depositing alumina onto bundles of “endless” carbon fibers via pulsed chemical vapor deposition and subsequent removal of the fibers. Thin alumina films were deposited onto “endless” carbon fibers at 77 °C by gas phase exposures to sequential pulses of trimethylaluminum and water vapor, respectively. The carbon fibers were selectively removed using thermal oxidation in air at temperatures exceeding 550 °C. The length of the tubes was primarily limited by the dimension of the used furnace. The longest tubes thus had a length of 30 cm. Scanning electron microscopic (SEM) images of the microtubes revealed that each individual tube was separated from its neighbors and that the tubes had an almost uniform wall thickness. SEM and transmission electron microscopic (TEM) images indicate that the inner side of the wall has the same morphology as the fiber template. As deposited, the alumina films have a predominantly amorphous structure; this is transformed into a polycrystalline structure during thermal oxidation. At low thermal oxidation temperatures, such as 550 °C, the alumina microtubes still comprise a substantial fraction of amorphous structure, at higher oxidation temperatures, 900 °C or above, a dominating polycrystalline structure (with bigger grains) is formed. This transformation gives rise to grain boundaries. These grain boundaries might facilitate oxygen diffusion and thus oxidative removal of the fiber templates.     

Improvement of adhesion of DLC coating on nitinol substrate by hybrid ion beam deposition technique

Diamond-like carbon (DLC) films were prepared for a protective coating on nitinol substrate by hybrid ion beam deposition technique with an acetelene as a source of hydrocarbon ions. An amorphous silicon (a-Si) interlayer was deposited on the substrates to ensure better adhesion of the DLC films followed by Ar ion beam treatment. The film thickness increased with increase in ion gun anode voltage. The residual stresses in the DLC films decreased with increase in ion gun anode voltage and film thickness, while the stress values were independent of the radio frequency (RF) bias voltage. The adhesion of the DLC film was improved by surface treatment with argon ion beam for longer time and by increasing the thickness of a-Si interlayer.     

Adherent amorphous hydrogenated carbon films on metals deposited by plasma enhanced chemical vapor deposition

This paper reports the findings of a study of the structural, mechanical, and tribological properties of amorphous hydrogenated carbon (a-C:H) coatings for industrial applications. These thin films have proven quite advantageous in many tribological applications, but for others, thicker films are required. In this study, in order to overcome the high residual stress and low adherence of a-C:H films on metal substrates, a thin amorphous silicon interlayer was deposited as an interface. Amorphous silicon and a-C:H films were grown by using a radio frequency plasma enhanced chemical vapor deposition system at 13.56 MHz in silane and methane atmospheres, respectively. The X-ray photoelectron spectroscopy technique was employed to analyze the chemical bonding within the interfaces. The chemical composition and atomic density of the a-C:H films were determined by ion beam analysis. The film microstructure was studied by means of Raman scattering spectroscopy. The total stress was determined through the measurement of the substrate curvature, using a profilometer, while micro-indentation experiments helped determine the films' hardness. The friction coefficient and critical load were evaluated by using a tribometer. The results showed that the use of the amorphous silicon interlayer improved the a-C:H film deposition onto metal substrates, producing good adhesion, low compressive stress, and a high degree of hardness. SiC was observed in the interface between the amorphous silicon and a-C:H films. The composition, the microstructure, the mechanical and tribological properties of the films were strongly dependent on the self-bias voltages. The tests confirmed the importance of the intensity of ion bombardment during film growth on the mechanical and tribological properties of the films.