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1.
Carbon nitride thin films with different nitrogen concentration have been deposited at different N2 and N2/Ar mixed partial pressures. Time-integrated optical emission spectroscopy measurements have been performed to gather information on the nature of the chemical species present in the plasma. Both the CN and C2 molecular species have been observed. Fast photography imaging of the expanding plume revealed the change of the dynamics from a free expansion at low pressure to a shock wave formation followed then by the plume stopping upon increasing the gas pressure values. Raman and XPS spectroscopy measurements performed on the deposited thin films revealed that the films, structure strongly depends on the dynamics of the expansion plasma regime rather than on the partial pressure at which the deposition takes place.  相似文献   

2.
Carbon nitride (CNx) thin films have been grown on Si 〈1 0 0〉 by 193 nm ArF ns pulsed laser ablation of a pure graphite target in a low pressure atmosphere of a RF generated N2 plasma and compared with samples grown by PLD in pure nitrogen atmosphere. Composition, structure and bonding of the deposited materials have been evaluated by X-ray photoelectron spectroscopy (XPS), and Raman scattering. Significant chemical and micro-structural changes have been registered, associated to different nitrogen incorporation in the two types of films analyzed. The intensity of the reactive activated species is, indeed, increased by the presence of the bias confined RF plasma, as compared to the bare nitrogen atmosphere, thus resulting in a different nitrogen uptake in the growing films. The process has been also investigated by some preliminary optical emission studies of the carbon plume expanding in the nitrogen atmosphere. Optical emission spectroscopy reveals the presence of many excited species like C+ ions, C atoms, C2, N2; and CN radicals, and N2+ molecular ions, whose relative intensity appears to be increased in the presence of the RF plasma. The films were also characterised for electrical properties by the “four-probe-test method” determining sheet resistivity and correlating surface conductivity with chemical composition.  相似文献   

3.
Solid-phase processes in thin films (~200 nm) based on tin and indium oxides (ITO structures) prepared by magnetron sputtering from a composite target (93 at % In and 7 at % Sn) and by layer-by-layer deposition of In/Sn/Si and Sn/In/Si structures from two magnetrons in a single vacuum cycle have been investigated in the work under their oxidation in an oxygen flow. Two ways of optically transparent semiconductor film formation have been compared using near-edge fundamental absorption spectroscopy, x-ray diffraction analysis, and electron microscopy and dynamics of the change in their optical and structure properties has been studied. In the case of oxidation of the layer-by-layer deposited structures, the heterogeneous phase composition of the film is confirmed both by the XRD data and by the optical results. Only wide-band-gap phases with an energy of direct transitions of 3.5–3.6 eV have been found in the films prepared by magnetron sputtering from a composite target after their oxidation. These wide-band-gap phases are associated with In2O3 oxide and a tin-doped indium oxide compound.  相似文献   

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ZnO plasma produced by third harmonic 355 nm of Nd:YAG laser at various ambient pressures of oxygen was used for depositing quality nanocrystalline ZnO thin films. Time and space resolved optical emission spectroscopy is used to correlate the plasma properties with that of deposited thin films. The deposited films showed particle size of 8 and 84 nm at ambient oxygen pressure of 100 and 900 mTorr, respectively. Third harmonic generation observed in ZnO thin films deposited under 100 mTorr of ambient oxygen is reported.  相似文献   

7.
Thin films of La0.6Ca0.4CoO3 were grown by pulsed laser ablation with nanosecond and femtosecond pulses. The films deposited with femtosecond pulses (248 nm, 500 fs pulse duration) exhibit a higher surface roughness and deficiency in the cobalt content compared to the films deposited with nanosecond pulses (248 nm, 20 ns pulse duration). The origin of these pronounced differences between the films grown by ns and fs ablation has been studied in detail by time-resolved optical emission spectroscopy and imaging. The plumes generated by nanosecond and femtosecond ablation were analyzed in vacuum and in a background pressure of 60 Pa of oxygen. The ns-induced plume in vacuum exhibits a spherical shape, while for femtosecond ablation the plume is more elongated along the expansion direction, but with similar velocities for ns and fs laser ablation. In the case of ablation in the background gas similar velocities of the plume species are observed for fs and ns laser ablation. The different film compositions are therefore not related to different kinetic energies and different distributions of various species in the plasma plume which has been identified as the origin of the deficiency of species for other materials.  相似文献   

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TiO2/Al2O3/TiO2/Al2O3 multilayer structures were obtained at different oxygen:argon gas ratios of 20:80, 30:70, 50:50 and 60:40 sccm and constant rf power of 200 W using reactive magnetron sputtering. Grain size and elemental distribution in the films were studied from AFM image and XPS spectra respectively. The deposited grain size increased with increasing oxygen:argon gas ratio. The optical band gap, refractive index, extinction coefficient were calculated from UV-vis transmittance and reflectance spectra. It was observed that the value of refractive index, extinction coefficient and band gap increased with increasing oxygen. These variations are due to the defects levels generated by the heterostructure and explained by the PL spectrum. The antireflecting (AR) efficiency of the films was estimated from the reflectance spectra of the films. Broad band antireflecting coating for the visible range was achieved by varying oxygen content in the film. The plasma chemistry controlled the antireflecting property by the interface interdiffusion of atoms during layer transition in multilayer deposition. The in situ investigation of the plasma chemistry was performed using optical emission spectroscopy. The plasma parameters were estimated and correlated with the characteristics of the films.  相似文献   

10.
采用脉冲激光沉积方法在单晶Si(100)衬底上制备出c轴取向的Zn1-xMgxO单晶薄膜,通过荧光光谱仪研究了薄膜的光致发光特性.实验结果表明,Mg含量增加,Zn1-xMgxO单晶薄膜的紫外发光峰蓝移,发光峰强度减弱,缺陷发光强度增强.同时发现,由于Mg的掺杂,引入了一些束缚能较大的局域束缚态.对于氧气氛下制备的样品,实验发现紫外峰和绿光带发光峰同时增强,但是R值减小,紫外峰红移.对绿光发光机理研究发现,绿光发光带主要与锌空位、氧间隙(Oi)或锌位氧(OZn)等缺陷有关,它是由多个缺陷发光峰组成,各缺陷发光峰强度相对变化导致了绿光发光带的整体移动. 关键词: 1-xMgxO薄膜')" href="#">Zn1-xMgxO薄膜 光致发光 脉冲激光沉积  相似文献   

11.
Tin oxide films have been prepared by oxidation of Sn thin films deposited by thermal evaporation method onto glass substrates. The oxidation of films was done, in air at a temperature of 500 °C, from 20 to 120 min. The oxidized films were characterized by X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), photoluminescence spectroscopy (PL) and surface profilometer. The XRD patterns show that the crystalline structure of the oxidized Sn films improves with the annealing time. The tetragonal SnO2 phase (cassiterite) was obtained after 120 min of annealing with grains sizes between 15 and 20 nm. The thickness of oxide films, as function of the annealing time, follows a parabolic law. The O/Sn atomic ratio increases with the annealing time indicating an improvement of the films quality. Tin interstitials defects density, calculated from PL spectra using Smakula's formula, was found to decrease with the increasing annealing time. Tin interstitials defects density was found proportional to the increasing oxygen density (deduced from RBS). A fit of this proportionality allowed us to quantify the tin cations and oxygen anions diffused through the oxide films.  相似文献   

12.
A Gallium Arsenide target has been ablated by using a frequency-doubled Nd:glass laser with a pulse duration of 250 fs and thin films have been deposited in vacuum. The plasma produced by the ablation process and the deposited films have been studied by several different techniques, including optical emission spectroscopy, ICCD fast imaging and electron microscopies, X-ray diffraction, Raman spectroscopy, respectively. The data evidence that the films, which composition shows an excess of Ga, are formed by the coalescence of a large number of nanoparticles. These results, even if the plasma does not evidence the presence of nanoparticles, seem to indicate that the ablation-deposition mechanism is the same found for the majority of the other systems deposited by ultra-short pulse lasers.  相似文献   

13.
In this work, we used a crossed plasma configuration where the ablation of two different targets in a reactive atmosphere was performed to prepare nanocrystalline thin films of ternary compounds. In order to assess this alternative deposition configuration, titanium carbonitride (TiCN) thin films were deposited. Two crossed plasmas were produced by simultaneously ablating titanium and graphite targets in an Ar/N2 atmosphere. Films were deposited at room temperature onto Si (100) and AISI 4140 steel substrates whilst keeping the ablation conditions of the Ti target constant. By varying the laser fluence on the carbon target it was possible to study the effect of the carbon plasma on the characteristics of the deposited TiCN films. The structure and composition of the films were analyzed by X-ray Diffraction, Raman Spectroscopy and non-Rutherford Backscattering Spectroscopy. The hardness and elastic modulus of the films was also measured by nanoindentation. In general, the experimental results showed that the TiCN thin films were highly oriented in the (111) crystallographic direction with crystallite sizes as small as 6.0 nm. It was found that the hardness increased as the laser fluence was increased, reaching a maximum value of about 33 GPa and an elastic modulus of 244 GPa. With the proposed configuration, the carbon content could be easily varied from 42 to 5 at.% by changing the laser fluence on the carbon target.  相似文献   

14.
Zinc oxide thin films have been obtained by reactive pulsed laser ablation of a Zn target in O2 atmosphere (gas pressure 2 Pa) using a doubled frequency Nd:YAG laser (532 nm) which was also assisted by a 13.56 MHz radiofrequency (rf) plasma. The gaseous species have been deposited on Si(100) substrates positioned in on-axis configuration and heated from RT up to 500 °C. The obtained thin films have been compared to those produced in the same conditions by ablation of a ZnO target. The deposited thin films have been characterized by scanning electron microscopy, X-ray diffraction, Raman and infrared spectroscopy techniques. The influence of the rf plasma on the morphological and structural characteristics of these thin films is also briefly discussed. PACS 81.15.Fg; 68.55.Jk; 78.30.j  相似文献   

15.
Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films were deposited by RF plasma enhanced chemical vapor deposition (PECVD) and subsequently annealed in N2 atmosphere at different temperatures. Systematic investigations of the deposition temperature and annealing effect on the film's properties, including film thicknesses, optical bandgap, refractive indexes, absorption coefficient (α), chemical bond configurations, stoichiometry and crystalline structures, were performed using ellipsometry, FTIR absorbance spectroscopy, Raman spectroscopy, XPS, and XRD. All of the results indicate that the structural and optical properties of the a-Si1-xCx:H film can be effectively engineered by proper annealing conditions. Moreover, molecular vibrational level equation was introduced to explain the peak shift detected by FTIR and Raman spectroscopy.  相似文献   

16.
The plasma produced by ultra-short laser ablation of ZrB2 and ReB2 has been studied by ICCD imaging and time and space resolved optical emission spectroscopy. The aim was to clarify the mechanism of deposition leading to the morphology and composition found in the deposited films. The results indicate that for all systems the film characteristics are compatible with a deposition mechanism involving a growth from nanoparticles, ejected directly from the target, whose composition can be interpreted in terms of equilibrium vaporization during the flight from the target to the substrate.  相似文献   

17.
Opacity effects on extreme ultraviolet (EUV) emission from laser-produced tin (Sn) plasma have been experimentally investigated. An absorption spectrum of a uniform Sn plasma generated by thermal x rays has been measured in the EUV range (9-19 nm wavelength) for the first time. Experimental results indicate that control of the optical depth of the laser-produced Sn plasma is essential for obtaining high conversion to 13.5 nm-wavelength EUV radiation; 1.8% of the conversion efficiency was attained with the use of 2.2 ns laser pulses.  相似文献   

18.
The propagation of LaMnO3 laser ablation plume in oxygen background has been investigated using fast photography of overall visible plume emission and time-resolved optical emission spectroscopy. The plume expansion was studied with ambient oxygen pressures ranging from vacuum level to 100 Pa. Free-expansion, splitting, sharpening and stopping of the plume were observed at different pressures and time delays after the laser pulse. Time-resolved optical emission spectroscopy showed that oxides are mainly formed through reaction of the atomic species ablated from the target with oxygen in the gas-phase. These reactions mainly affect the content of lanthanum oxide in the plume, while emission of manganese oxide is barely observed in all the range of pressure investigated.  相似文献   

19.
宁兆元  程珊华  叶超 《物理学报》2001,50(3):566-571
使用CHF3和C6H6混合气体做气源,在一个电子回旋共振等离子体增强化学气相沉积装置中制备了氟化非晶碳(a-CFx)薄膜.利用发射光谱研究了等离子体中形成的各种碳氟、碳氢基团随放电宏观参量的变化规律,对薄膜做了傅里叶变换红外光谱和X射线光电子能谱分析,证实等离子体中的CF2,CF和CH基团是控制薄膜生长、碳/氟成分比和化学键结构的主要前驱物 关键词: 氟化非晶碳薄膜 电子回旋共振等离子体  相似文献   

20.
Laser ablation coupled to mass quadrupole spectrometry (LAMQS) has been used to prepare thin films of aluminum oxide deposited on Si substrates starting from commercial Al2O3 polycrystalline targets. X-ray photoemission (XPS) and reflection electron energy loss spectroscopy (REELS) have allowed the investigation of the electronic properties of the produced films. In particular, it was found that the Al/O atomic ratio assumes a value very near to 0.7 (stoichiometric ratio) only for films deposited normally with respect to the target surface, while films grown at larger deposition angles are more rich in oxygen content.The composition, the mass density, the optical energy gap, the complex dielectric function and refraction index of the films have been calculated and compared with the results obtained from our starting target material and with the literature. The morphology of the deposited samples has been analyzed by the AFM technique.  相似文献   

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