Heteroepitaxy of Ir films on silicon with a ceria/yttria stabilized zirconia buffer layer

Heteroepitaxial Ir films on Si(001) with a double ceria/yttria stabilized zirconia heteroepitaxial buffer layer were grown by magnetron sputtering. As-deposited CeO₂ films covered with {111} faceted pyramids resulted in iridium films with the [001] axis normal to the substrate plane. The buffered substrates annealed at 1115 °C have a smooth surface; Ir films on such substrates have the (111) orientation and consist of grains turned at 90° toward each other.     

Nanostructured Ni3Al layers and Ni3Al/Ni multilayers obtained by magnetron sputtering

Intermetallic Ni₃Al thin layers and Ni₃Al/Ni multilayers were deposited on a Si wafer by means of magnetron sputtering. The structure and morphology of the layers have been characterized by X-ray diffraction, transmission electron microscopy and atomic force microscopy. The polycrystalline films are textured in the (111) direction and have grain sizes below 20 nm. Superlattice reflections due to chemical order have been observed in the electron microscope. It is shown by x-ray diffraction that the multilayers grow coherently on the amorphous substrate.     

Comparisons on the properties of (Zn1-xCox)2-W type barium hexaferrite thin films prepared on the Si (100) and (111) substrates

The (Zn_1-xCo_x)₂-W type barium hexaferrite thin films have been prepared by a radio frequency magnetron sputtering method on the Si (100) and the Si (111) substrates respectively. With increasing the annealing temperatures (800, 850, 900, 950, and 1000 °C), the Ba(CoZn)₂Fe₁₆O₂₇ phases emerge from the amorphous matrix. The hexaferrite thin films on Si (111) substrates have a larger saturation magnetic field (636.6 kA/m) than those on Si (100) substrates (159.1 kA/m). The magnetic hysteresis measurements show that they exhibit an isotropic behavior for thin films deposited on both substrates. Films on the Si (111) substrates are magnetically harder than those on the Si (100) substrates.     

Synthesis of GaN nanorods by ammoniating Ga2O3 films on In2O3 layer deposited on Si (111) substrates

GaN nanorods were synthesized by ammoniating Ga₂O₃/In₂O₃ thin films deposited on Si (111) with magnetron sputtering. X-ray diffraction, Scanning electronic microscope and high-resolution TEM results show that they are GaN single crystals, the sizes of which vary from 2 to 7 μm in length and 200 to 300 nm in diameter. In₂O₃ middle layer plays an important role in the GaN nanorod growth.     

Preparation of single-crystal TiC (111) by radio frequency magnetron sputtering at low temperature

Single-crystal films of TiC (111) have been synthesized at room temperature on Al₂O₃ (0001) substrates by radio frequency magnetron sputtering using a compound Ti-C target. The substrate temperature and bias were varied to explore the influence of deposition parameters on the crystal structure. Both Al₂O₃ (0001) and Si (100) substrates were used for epitaxial growth of TiC films. A series of characterizations of TiC films were carried out, including Rutherford backscattering spectroscopy, X-ray diffraction, Raman and X-ray photoelectron spectroscopy. Single-crystal films of TiC (111) on the Al₂O₃ (0001) were demonstrated.     

Anisotropic crystallite size analysis of textured nanocrystalline silicon thin films probed by X-ray diffraction

A newly developed X-ray technique is used, which is able to quantitatively combine texture, structure, anisotropic crystallite shape and film thickness analyses of nanocrystalline silicon films. The films are grown by reactive magnetron sputtering in a plasma mixture of H₂ and Ar onto amorphous SiO₂ and single-crystal (100)-Si substrates. Whatever the used substrate, preferred orientations are observed with texture strengths around 2-3 times a random distribution, with a tendency to achieve lower strengths for films grown on SiO₂ substrates. As a global trend, anisotropic shapes and textures are correlated with longest crystallite sizes along the 〈111〉 direction but absence of 〈111〉 oriented crystallites. Cell parameters are systematically observed larger than the value for bulk silicon, by approximately 0.005-0.015 Å.     

Growth and characterization of yttrium oxide films by reactive magnetron sputtering

Yttrium oxide (Y₂O₃) is a promising ceramic material for electronic and optical applications due to its excellent properties. The purpose of this study is to characterize the effects of deposition parameters on the structure and composition of Y₂O₃ films. The films are grown on Si substrates by reactive magnetron sputtering at different substrate temperatures and oxygen pressures. The composition and structure of the films are studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. It is shown that the Y₂O₃ films deposited by reactive magnetron sputtering are mainly cubic phase and polycrystalline. The films are composed of Y-O, Y-O-Si, and Si-O bonds. Increasing substrate temperature induces the monoclinic to cubic phase transition and results in the formation of oxygen vacancies in the film. The preferred growth orientation of Y₂O₃ film is the (110) plane at low temperature, and it changes to the (111) plane at high temperature. The low temperature is preferable for the formation of Y-O bonds. The oxygen pressure influences on the concentration of Y-O bonds significantly. An optimal oxygen partial pressure for the formation of Y-O bonds exists during the film deposition. In addition, the deposited Y₂O₃ films exhibit excellent mechanical properties.     

钠钙玻璃上Mg2Si薄膜的制备及其电学性质

采用磁控溅射技术和退火工艺在钠钙玻璃衬底上制备了Mg_2Si半导体薄膜,研究了Mg膜厚度对Mg_2Si薄膜结构及其电学性质的影响。在钠钙玻璃上分别溅射两组相同厚度(175nm)的P-Si和N-Si膜,然后在其上溅射不同厚度Mg膜(240nm、256nm、272nm、288nm、304nm),低真空退火4h制备一系列Mg_2Si半导体薄膜。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、霍尔效应测试仪对Mg_2Si薄膜的晶体结构、表面形貌、电学性质进行表征与分析。结果表明:采用磁控溅射技术在钠钙玻璃衬底上成功制备出以Mg_2Si(220)为主的Mg_2Si薄膜。随着沉积Mg膜厚度的增加,Mg_2Si衍射峰逐渐增强,薄膜表面更连续,电阻率逐渐减小,霍尔迁移率逐渐降低,载流子浓度逐渐增加。此外,Si膜导电类型和Mg膜厚度共同影响Mg_2Si薄膜的导电类型。溅射N-Si膜时,Mg_2Si薄膜的导电类型随着Mg膜厚度的增加由P型转化为N型;溅射P-Si膜时,Mg_2Si薄膜的导电类型为P型。可以控制制备的Mg_2Si半导体薄膜的导电类型,这对Mg_2Si薄膜的器件开发有着重要的指导意义。     

Influence of substrate and Ar/N<Subscript>2</Subscript> gas flow ratio on structural,optical and electrical properties of TiN thin films synthetized by DC magnetron sputtering

Titanium nitride (TiN) thin films have been prepared by direct-current reaction magnetron sputtering technique on different substrates (glass and Si) and the influence of substrate and Ar/N₂ gas flow ratio on structural, optical and electrical properties of TiN thin films were discussed. X-ray diffraction suggested that with the ratio of Ar/N₂ decreasing, the diffraction intensity of (111) plane gradually diminished while (200) plane increased and films on Si substrate exhibited better crystalline quality than glass substrate. Improvement of Ar/N₂ ratio is contribute to enhance the deposition rate and the obvious surface roughness were observed when the ratio up to 49. Photoluminescence spectra showed that TiN films on Si substrate showed higher intrinsic emission and lower defect emission. Moreover, the resistivity of TiN films showed obviously decreasing as the flow rate ratio of Ar/N₂ increased, especially films on Si substrate.     

Electrical properties of boron- and phosphorous-doped microcrystalline silicon thin films prepared by magnetron sputtering of heavily doped silicon targets

The boron(B)- and phosphorous(P)-doped microcrystalline silicon (Si) thin films were prepared by magnetron sputtering of heavily B- and P-doped Si targets followed by rapid thermal annealing (RTA), their electrical properties were characterized by temperature-dependent Hall and resistivity measurements. It was observed that the dark conductivity and carrier concentration of the 260 nm B-doped Si films annealed at 1,100 °C in Ar were 3.4 S cm^?1 and 1.6 × 10¹⁹ cm^?3, respectively, which were about one order of magnitude higher than that of P-doped Si films. The activation energy of the B- and P-doped Si films were determined to be 0.23 eV and 0.79 eV, respectively. The dark conductivity of B- and P-doped Si films increased with the increase of film thickness, RTA temperature, and the incorporation of H₂ in Ar during RTA. The present work provides an easy and non-toxic method for the preparation of doped microcrystalline Si thin films.     

Growth of VO2 films with metal-insulator transition on silicon substrates in inductively coupled plasma-assisted sputtering

Single-phase monoclinic vanadium dioxide (VO₂) films were grown on a Si(100) substrate using inductively coupled plasma (ICP)-assisted sputtering with an internal coil. The VO₂ film exhibited metal-insulator (M-I) transition at around 65 °C with three orders of change in resistivity, with a minimum hysteresis width of 2.2 °C. X-ray diffraction showed structural phase transition (SPT) from monoclinic to tetragonal rutile VO₂. For conventional reactive magnetron sputtering, vanadium oxides with excess oxygen (V₂O₅ and V₃O₇) could not be eliminated from stoichiometric VO₂. Single-phase monoclinic VO₂ growths that are densely filled with smaller crystal grains are important for achieving M-I transition with abrupt resistivity change.     

Effects of physical growth conditions on the structural and optical properties of sputtered grown thin HfO2 films

HfO₂ thin films were prepared by reactive DC magnetron sputtering technique on (100) p-Si substrate. The effects of O₂/Ar ratio, substrate temperature, sputtering power on the structural properties of HfO₂ grown films were studied by Spectroscopic Ellipsometer (SE), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, and X-ray photoelectron spectroscopy (XPS) depth profiling techniques. The results show that the formation of a SiO_x suboxide layer at the HfO₂/Si interface is unavoidable. The HfO₂ thickness and suboxide formation are highly affected by the growth parameters such as sputtering power, O₂/Ar gas ratio during sputtering, and substrate temperature. XRD spectra show that the deposited films have (111) monoclinic phase of HfO₂, which is also supported by FTIR spectra. XPS depth profiling spectra shows that highly reactive sputtered Hf atoms consume some of the oxygen atoms from the underlying SiO₂ to form HfO₂, leaving Si-Si bonds behind.     

A single phase semiconducting Ca-silicide film growth by sputtering conditions,annealing temperature and annealing time

Ca films were directly deposited on Si(100) substrates under the same sputtering power and Ar flux by Radio frequency (R.F.) magnetron sputtering system (MS) and were subsequently annealed at 800 °C for 90 min in a vacuum furnace. The structural and morphological features of the resultant films are tested by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive analysis of X-rays (EDAX). The cubic phase Ca₂Si film, the simple orthorhombic phase Ca₂Si film, and the tetragonal phase Ca₅Si₃ film are grown directly and individually on Si(100) substrates, respectively. The experimental results indicate that the selective growth of a single phase Ca-silicide from Ca–Si system of the existence of multiple silicide phases depends on sputtering conditions, annealing temperature, and annealing time. Besides, 800 °C is the adaptive annealing temperature for a single phase Ca-silicide film growth.     

Effect of electron beam irradiation on structure and properties of SiCN thin films prepared by plasma assisted radio frequency magnetron sputtering

Silicon carbon nitride thin films were deposited on Si (100) substrate at room temperature by plasma assisted radio frequency magnetron sputtering. The bonding structure and properties of SiCN films irradiated by pulsed electron beams were studied by means of X-ray photoelectron spectroscopy and nano-indentation. The results showed that electron beam irradiation had a great effect on the structure and property of the films. Under sputtering gas pressure of 3.7 Pa, a transition from the (Si,C)N_x bonded structure to the (Si,C)₃N₄ bonded structure was found in the SiCN thin film with electron beam irradiation. At sputtering gas pressure of 6.5 Pa, the enhancement of hardness in the SiCN film after treatment with electron beam irradiation resulted from the promotion of the sp³-hybridization of carbons bonds.     

Au/Ni bilayers on n-type silicon: Metallurgical and electrical behaviour

Diffusion effects during the formation of silicides in the Ni-Au-Si system were investigated by means of ⁴He⁺ MeV Rutherford backscattering spectrometry, Auger electron spectroscopy coupled with Ar⁺ ion sputtering and X-ray diffraction as a function of the heat treatment temperature (280–350°C) and time (10–1000 min). Schottky barrier heights were used to identify the type of metal present at the silicon surface. Au/Ni/Si and Ni/Au/Si structures were prepared by electron gun deposition of thin gold and nickel films onto n-type Si〈111〉 single crystals. After thermal treatment only Ni₂Si and NiSi compounds were observed and their formation follows the phase order confirmed by previous investigations on the Ni/Si system, with a growth controlled by a lattice diffusion process. In the Ni/Au/Si〈111〉 structure the diffusion of the silicon through the gold film was detected during the formation of nickel silicide and the kinetics of growth of Ni₂Si and NiSi were similar to those studied in the Ni/Si〈100〉 system. A diffusion of gold towards the Si-NiSi interface was observed during the growth of NiSi in the Au/Ni/Si〈111〉 structure. The Schottky barrier height measurements confirm these findings.     

Effect of electron beam irradiation on structure and properties of SiCN thin films prepared by plasma assisted radio frequency magnetron sputtering

Silicon carbon nitride thin films were deposited on Si (100) substrate at room temperature by plasma assisted radio frequency magnetron sputtering. The bonding structure and properties of SiCN films irradiated by pulsed electron beams were studied by means of X-ray photoelectron spectroscopy and nano-indentation. The results showed that electron beam irradiation had a great effect on the structure and property of the films. Under sputtering gas pressure of 3.7 Pa, a transition from the (Si,C)N_x bonded structure to the (Si,C)₃N₄ bonded structure was found in the SiCN thin film with electron beam irradiation. At sputtering gas pressure of 6.5 Pa, the enhancement of hardness in the SiCN film after treatment with electron beam irradiation resulted from the promotion of the sp³-hybridization of carbons bonds.     

Effect of ammoniating temperature on microstructure of one-dimensional GaN nanorods with Tb intermediate layer

GaN nanorods have been successfully synthesized on Si (111) substrates by magnetron sputtering through ammoniating Ga₂O₃/Tb thin films. The influence of ammonating temperatures on microstructure, morphology and light emitting properties of GaN nanorods was ananlyzed in detail using X-ray diffraction, X-ray photoelectron spectroscopy, FT-IR spectrophotometer, scanning electron microscopy, high- resolution transmission electron microscopy, and photoluminescence spectroscopy. The results demonstrate that the GaN nanorods are single crystalline and exhibit hexagonal wurtzite symmetry. The highest crystalline quality was achieved at 950 °C for 15 min with the size of 100–150 nm in diameter, which have an excellent light emitting properties. A small red-shift occurs due to band-gap change caused by the tensile stress.     

Growth mechanism of epitaxial CoSi2 on Si and reactive deposition epitaxy of double heteroepitaxial Si/CoSi2/Si

The growth mechanism of epitaxial CoSi₂ was studied using Co/Ti/Si multilayer solid phase reaction. Results showed that phase formation was controlled by diffusion of Co through the growing CoSi_x, although at the early stage of CoSi₂ growth the diffusion of Co could be controlled by a Ti layer. A reactive deposition technique was also evaluated by using a conventional magnetron sputtering system. Results showed that an epitaxial CoSi₂ layer was formed by controlling the Co sputtering rate not to exceed the Co diffusion rate through CoSi_x. However, the surface of CoSi₂ became rough when the deposition rate was much slower than the Co diffusion rate through CoSi_x. The roughness was caused by the formation of CoSi₂ (111) facets at the interface between CoSi₂ and the Si substrate. Si/CoSi₂/Si double heteroepitaxial structures were fabricated when Si and Co were sequentially sputter-deposited on a Si (100) substrate.     

Underlayer dependence of microtexture, microstructure and magnetic properties of c-axis oriented strontium ferrite thin films

Strontium ferrite (SrM) thin films were prepared by dc magnetron sputtering system on thermally oxidized silicon wafer (SiO₂/Si), single-crystal sapphire with (00l) orientation and single-crystal MgO with (111) orientation and the effect of Au and Pt underlayers on morphology and magnetic properties was studied. Experimental results revealed that with the application of underlayers, the crystallization temperature of SrM was reduced. Strontium ferrite thin films with uniaxial anisotropy were formed on all substrate specimens. Comparison of the results obtained on all thin films indicated that the maximum saturation magnetization and coercivity in the perpendicular direction were 0.377 T and 0.382 MAm^− 1, respectively, for thin films with Au underlayer and SiO₂/Si substrate.     

Growth and structure of PbWO<Subscript>4</Subscript> films

Lead tungstate films have been grown on silicon by magnetron sputtering followed by heat treatment at various temperatures. The thermal oxidation of metal-oxide (Pb/WO₃/Si and W/PbO₂/Si) and metal-metal (Pb/W/Si) bilayer systems at temperatures above 870 K yields films that are dominated by monoclinic PbWO₄ and contain WO₃, also monoclinic. The optimal configuration for PbWO₄ synthesis is Pb/WO₃/Si because, even during lead deposition onto tungsten oxide, we observe the formation of lead tungstate, PbWO₄, and subsequent heat treatment increases the percentage of this phase in the film.