Middle-frequency magnetron sputtering for GaN growth

A middle-frequency magnetron sputtering system was designed and constructed for GaN growth, in which a pair of back cooled pool-shaped twin magnetrons were used for Ga metal targets. GaN films were prepared using this system under various gas pressure (0.5-3.0 Pa) in a mixture of N₂ and Ar with N₂/Ar ratio of 6:1. X-ray diffraction showed that the GaN films had a strong (0 0 0 2) orientation, and the film deposited at 1.5 Pa had two more weak peaks attributed to and . The full width at half maximum (FWHM) of the (0 0 0 2) peak for the GaN film deposited at 1.5 Pa and 0.5 Pa is ∼721 and ∼986 arcsec, respectively. The deposition rate was in the range of 43.5-87.8 nm/min and was mainly influenced by the deposition pressure. The films deposited at higher pressures are columnar in structure. A root-mean-square roughness of 4.4 nm was obtained from the atomic force microscopy (AFM) surface morphology of the film deposited at 0.5 Pa.     

Structural study of the oxidation process and stability of NbOxNy coatings

In the present work, we study the oxidation behaviour of NbON multilayer films. The films were deposited by DC magnetron sputtering with a reactive gas pulsing process. The nitrogen flow was kept constant and the oxygen flow was pulsed. Pulse durations of 10 s produced multilayered coatings with a period of λ = 10 nm. Three different films with increasing duty cycles have been deposited.Rutherford backscattering spectroscopy (RBS) was used to study the chemical composition variations at different annealing temperatures (as-deposited, 400 °C, 500 °C and 600 °C) combined with X-ray diffraction (XRD) to identify the crystalline phases formed. At 400 °C, for all films a very thin layer starts to form at the surface with enhanced O concentration. The composition of the deeper part of the samples remains unchanged. At 500 °C, the oxide scale grows, encompassing about half the film thickness. At 600 °C, the process is finished and a single layer is formed with reduced Nb and increased O concentration. Fourier-transformation infrared spectroscopy (FTIR) results confirmed the increase of this surface oxidation, while XRD revealed that crystallization of Nb₂O₅ occurs at 600 °C.     

Nanoscratch study of ZnO thin films deposited using radio frequency magnetron sputtering

In this study, a radio frequency magnetron sputtering system was used to deposit zinc oxide (ZnO) thin films onto langasite substrates. The thickness of the ZnO film increased from 0.3 to 1.2 μm upon increasing the deposition power from 100 to 200 W. The predominant growth orientation was along the c-axis (0 0 2); the intensities of the signals in the X-ray diffraction spectrum increased significantly upon increasing the film thickness. Scanning electron microscopy images revealed columnar structures in the ZnO films and the morphology of ZnO grains is found to be continuous and dense. It is attributed that oxygen chemisorbs on the target and cases a surface layer of adsorbed oxygen. We suggest that the more neutral ion bombardment on the growing film which induces the higher sputtering rate of the growing film. From in situ imaging of scratched tracks, measurement of the coefficient of friction was an effective means of detecting the occurrence of structural defects in the microstructures. We also found that the chemical compositions of ZnO films prepared under various deposition powers could be investigated using X-ray photoelectron spectroscopy.     

Characteristics of TiVCrAlZr multi-element nitride films prepared by reactive sputtering

Nitride films of multi-element TiVCrAlZr alloy were prepared on silicon substrates by reactive radio-frequency magnetron sputtering under different nitrogen/argon flow ratios ranging from 0% to 66.7%. The alloy film deposited in pure argon exhibited an amorphous structure and a very smooth surface, while a face-center-cubic solid-solution structure with strong (2 2 0), (1 1 1) to (2 0 0) orientation and different fracture feature and surface morphologies was observed in those films which were prepared under various nitrogen flow ratios. With increasing nitrogen flow ratio, the hardness and elastic modulus of the films increased and reached maximum values of 11 and 151 GPa at 50%.     

Investigation of conductive and transparent ITO/Ni/ITO multilayer films deposited by a magnetron sputter process

Transparent conducting ITO/Ni/ITO films were deposited by RF magnetron sputtering of Sn-doped In₂O₃ and DC magnetron sputtering of Ni on unheated polycarbonate substrates. Ni interlayers with thicknesses of 5, 10, and 20 nm were used as intermediate metallic layers.Changes in the work function and optical, electrical and structural properties of the films were examined with respect to Ni layer thickness. The work function was measured to be about 4.5 eV and was found to be independent of Ni layer thickness. However, the structural, optical, and electrical properties of the films were influenced by the Ni thickness. As-deposited ITO single layer films showed In₂O₃ diffraction peaks for the (2 2 2) and (4 0 0) planes, while after insertion of the Ni layer between ITO films, these diffraction peaks disappeared. The electrical resistivity decreased with the Ni intermediated film and the optical transmittance also decreased due to increased optical absorption. The figure of merit reached a maximum of 2.0 × 10⁻³ Ω⁻¹ for a 5 nm-thick inserted Ni film, which is greater than the value for as-deposited ITO films.     

Hydrogen behavior in gasochromic tungsten oxide films investigated by elastic recoil detection analysis

Changes in the composition and crystalline structure of gasochromic tungsten oxide films resulting from the incorporation of hydrogen were investigated; the oxide films were prepared by reactive RF magnetron sputtering on SiO₂ and glassy carbon substrates simultaneously. X-ray diffraction analysis of the deposited films at 600 °C showed a uniaxial oriented structure in the (0 1 0) plane of monoclinic WO₃ for both substrates. The elastic recoil detection analysis (ERDA) and Rutherford backscattering spectroscopy (RBS) for the films on glassy carbon revealed that the hydrogen impurity was uniformly distributed up to a concentration of 0.24 H/W. The Pd-coated films on SiO₂ turned blue when they were exposed to a mixture of Ar and 5% H₂ gases. When the sample became colored, the hydrogen concentration in the film increased to 0.47 H/W and the crystalline structure of the film changed from monoclinic to tetragonal. These results indicated that the gasochromic coloration of the tungsten oxide films coincided with incorporation of hydrogen atoms into the crystalline lattice, corresponding to the formation of hydrogen tungsten bronze (H_xWO₃).     

溅射功率对磁控溅射制备Bi薄膜结构和性能的影响

采用直流磁控溅射方法在不同功率下制备了铋(Bi)薄膜,对薄膜的沉积速率、表面形貌、生长模式、晶体结构进行了研究,并对其晶粒尺寸和应力的变化规律进行了分析。扫描电镜(SEM)图像显示：薄膜均为柱状生长,平均晶粒尺寸随溅射功率先增大后减小,薄膜的致密度随着功率的增加而降低,在60W时又变得较致密。X射线衍射(XRD)结果表明：Bi薄膜均为多晶斜六方结构,薄膜内应力随功率的增加由张应力变为压应力。     

Swift heavy ion induced phase transition in CdTe films deposited by spray pyrolysis in presence of electric field

CdTe polycrystalline thin films possessing hexagonal phase regions are obtained by spray deposition in presence of a high electric field. Thin film samples are irradiated with 100 MeV Ag ions using Pelletron accelerator to study the swift heavy ion induced effects. The ion irradiation results in the transformation of the metastable hexagonal regions in the films to stable cubic phase due to the dense electronic excitations induced by beam irradiation. The phase transformation is seen from the X-ray diffraction patterns. The band gap of the CdTe film changes marginally due to ion irradiation induced phase transformation. The value changes from 1.47 eV for the as deposited sample to 1.44 eV for the sample irradiated at the fluence 1×10¹³ ions/cm². The AFM images show a gradual change in the shape of the particles from rod shape to nearly spherical ones after irradiation.     

Effects of composition and structure on hydrogen incorporation in tungsten oxide films deposited by sputtering

The effects of composition and structure on hydrogen incorporation in tungsten oxide films were investigated. Films were deposited on carbon and SiO₂ substrates using a reactive sputtering by varying the substrate temperature from 30 to 600 °C in argon and oxygen mixture. The films were characterized using X-ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), elastic recoil detection analysis (ERDA) and Raman scattering. XRD patterns showed amorphous structure in the films deposited below 400 °C and (0 1 0) oriented monoclinic WO₃ in the films deposited beyond 400 °C. The results of RBS and ERDA indicated that hydrogen concentration in the amorphous films increased from 0.1 to 0.7 H/W with changing the composition from WO_0.25 to WO₃. The hydrogen concentration in WO₃ films decreased to 0.4 H/W with increasing the substrate temperature during deposition. The Raman spectra of the WO₃ films revealed that decreasing of W⁶⁺O terminals was related to decreasing of the hydrogen concentration. It was considered that the incorporated hydrogen in tungsten oxide films was bonded at the end of W⁶⁺O terminals.     

Growth and surface morphology of ion-beam sputtered Ti-Ni thin films

Titanium-nickel thin films have been deposited on float glass substrates by ion beam sputtering in 100% pure argon atmosphere. Sputtering is predominant at energy region of incident ions, 1000 eV to 100 keV. The as-deposited films were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). In this paper we attempted to study the surface morphology and elemental composition through AFM and XPS, respectively. Core level as well as valence band spectra of ion-beam sputtered Ti-Ni thin films at various Ar gas rates (5, 7 and 12 sccm) show that the thin film deposited at 3 sccm possess two distinct peaks at binding energies 458.55 eV and 464.36 eV mainly due to TiO₂. Upon increasing Ar rate oxidation of Ti-Ni is reduced and the Ti-2p peaks begin approaching those of pure elemental Ti. Here Ti-2p peaks are observed at binding energy positions of 454.7 eV and 460.5 eV. AFM results show that the average grain size and roughness decrease, upon increasing Ar gas rate, from 2.90 μm to 0.096 μm and from 16.285 nm to 1.169 nm, respectively.     

Effects of composition and structure on gasochromic coloration of tungsten oxide films investigated with XRD and RBS

The effects of composition and structure on gasochromic coloration of tungsten oxide films for hydrogen have been investigated. Tungsten oxide films with various O/W atomic ratios from 1.5 to 3.0 are prepared using a reactive rf magnetron sputtering from a tungsten target at different oxygen partial pressures. The films were deposited on quartz and carbon substrates at 200 °C. The O/W atomic ratio and crystallographic structure of the films were determined by Rutherford backscattering spectroscopy and X-ray diffraction. The gasochromic properties of the films were examined by use of optical transmittance in exposure in 1% H₂/Ar atmosphere. The stoichiometric WO₃ film with amorphous structure resulted in superior gasochromic coloration. The decrease in gasochromic performance was caused by non-stoichiometric WO₃ films with amorphous structure or stoichiometric WO₃ films crystallized with post-annealing at temperatures higher than 300 °C in air. It suggests that the gasochromic coloration of tungsten oxide films for hydrogen is strongly influenced by the composition and structure.     

Deposition of titanium nitride on Si(1 0 0) wafers using plasma focus

Titanium nitride thin films were deposited on Si(1 0 0) substrates by using a low energy (2.3 KJ) Mather-type plasma focus device. The composition of the deposited films was characterized by X-ray diffraction (XRD). The crystallite size has strong dependence on the numbers of focus shots. The crystallinity of TiN thin films is found to increase with increasing the number of focus shots. The effect of different number of focus shots on micro structural changes of thin films was characterized by Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM). SEM results showed net-like structure for film deposited for 15 numbers of shots, which are elongated grains of Si₃N₄ in amorphous form embedded into TiN crystals. The average surface roughness was calculated from AFM images of the thin films. These results indicated that the average surface roughness increased for films deposited with increased number of focus shots. The least crystallite size and roughness are observed for film deposited with 25 focus shots.     

直流磁控溅射钛及钛合金薄膜的性能研究

用直流磁控溅射的方法在Si及Mo基片上制取Ti及其Ti合金薄膜。研究了基片温度等镀膜工艺参数对薄膜性能的影响,并用XPS、XRD、SEM分析薄膜的化学组成和结构特征,对薄膜的生长模式进行分析。结果表明,合金的加入降低了晶粒尺寸;升高温度可增大薄膜晶粒尺寸,改善薄膜结合能力;合金膜的成分与靶材基本一致。     

Control of growth and structure of Ag films by the driving frequency of magnetron sputtering

The growth and structural properties of Ag films prepared by radio-frequency (2,13.56 and 27.12 MHz) and very-high-frequency (40.68 and 60 MHz) magnetron sputtering were investigated.Using 2 MHz sputtering,the Ag film has a high deposition rate,a uniform and smooth surface and a good fcc structure.Using 13.56 and 27.12 MHz sputtering,the Ag films still have a high deposition rate and a good fcc structure,but a non-uniform and coarse surface.Using 40.68 MHz sputtering,the Ag film has a moderate deposition rate and a good fcc structure,but a less smooth surface.Using 60 MHz sputtering,the Ag film has a uniform and smooth surface,but a low deposition rate and a poor fcc structure.The growth and structural properties of Ag films are related to the ions' energy and flux density.Therefore,changing the driving frequency is a good way to control the growth and structure of the Ag films.     

Ion beam characterization of rf-sputter deposited AlN films on Si(1 1 1)

Aluminum nitride (AlN) thin films have been deposited on Si(1 1 1) substrates by using reactive-rf-magnetron-sputtering at 250 °C. The crystalline quality and orientation of the films have been studied by X-ray diffraction (XRD). We have observed that the films grow with c- or a-axis orientation. The composition, film thickness, impurities and stress are considered to be factors affecting the orientation and have been analyzed by Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA) and XRD. Their effects on the film growth will be discussed. Surface morphology of the films will be also presented.     

Preparation of Al thin films charged with helium by DC magnetron sputtering

Helium atoms, up to 6.9 at.%, were introduced into Al films by DC magnetron sputtering in a He/Ar mixed atmosphere and distributed evenly in it. The relation between the He/Ar flux ratio, bias voltage, substrate temperature and helium concentration is studied. The helium concentration can be easily controlled by change of the process parameters and it greatly affects the morphology of film. TEM analysis suggests that small helium bubbles with a diameter of 1 nm are formed in the grain.     

SIMS study of effect of Cr adhesion layer on the thermal stability of silver selenide thin films on Si

Effect of heat treatment on silver selenide films grown from diffusion-reaction of Ag and Se films on Cr-buffered Si substrates was investigated up to 400 °C. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) were used to characterize the films. XRD patterns of the films showed stress assisted change in preferential orientation of the films upon annealing: the films annealed at 200 °C exhibited a strong orientation along (2 0 0) plane, which changed to (0 1 3) after annealing at 300 and 400 °C. Dynamic SIMS measurements showed that Cr is confined to the interface and that there is no diffusion of Cr into silver selenide.     

磁控溅射制备金属铀膜

研究了通过磁控溅射方法制备高纯金属铀膜的可行性。采用X射线衍射（XRD）、俄歇电子能谱（AES）、扫描电镜（SEM）、表面轮廓仪分析了沉积在单晶硅或金基材上铀薄膜的微观结构、成分、界面结构及厚度、表面形貌和表面粗糙度。分析结果表明：磁控溅射制备的铀薄膜为纯金属态,氧含量和其它杂质含量均低于俄歇电子能谱仪的探测下限;溅射沉积的铀镀层与铝镀层之间存在界面作用,两者相互扩散并形成合金相,扩散层厚度约为10nm。铀薄膜厚度可达微米级,表面光洁,均方根（RMS）粗糙度优于15nm。     

合金化对溅射Ti膜材结构和力学性能的影响

研究了直流磁控溅射Ti、TiMo、TiMoY及TiMoYAl薄膜的形貌、结构和力学性能,探讨了合金化对Ti膜的影响。结果表明,合金化使Ti膜由α相结构转变为α+β双相结构,改变了薄膜的择优取向,降低了薄膜表面粗糙度,并改善了薄膜的力学性能。     

Growth of silicon nitride films by bombarding amorphous silicon with N ions: MD simulation

In this study, the molecular dynamics simulation method was employed to investigate the growth of silicon nitride films by using N⁺ ions, with energies of 50, 100, 150 and 200 eV, to bombard an amorphous silicon surface at 300 K. After an initial period of N⁺ bombardment, saturation of the number of N atoms deposited on the surface is observed, which is in agreement with experiments. During subsequent steady state deposition, a balance between uptake of N by the surface and sputtering of previously deposited N is established. The Si(N_x) (x = 1-4) and N(Si_y) (y = 1-3) bond configurations in the grown films are analyzed.