沉积参数对化学气相沉积纳米金刚石薄膜的影响

用强电流直流伸展电弧化学气相沉积金刚石薄膜装置,在CH4-Ar和CH4-H2-Ar气氛中沉积了纳米金刚石薄膜,研究了沉积气氛中H2加入量和沉积压力对金刚石薄膜显微组织和生长机制的影响.沉积气氛中H2含量对金刚石薄膜的表面形貌、晶粒尺寸和生长速度有显著影响,随着H2含量增加,金刚石晶粒尺寸增大,薄膜生长速度提高.在1%CH4-Ar气氛中沉积的纳米金刚石薄膜,晶粒尺寸细小,薄膜表面形貌光滑平整.在1%CH4-少量H2-Ar气氛中沉积的金刚石薄膜,晶粒尺寸小于100nm,薄膜表面形貌较平整.随着沉积压力提高,金刚石薄膜的生长速度增大.用激光Ram an对金刚石薄膜进行了表征.     

Growth of diamond thin films by chemical vapour deposition

Deposition of diamond thin films on non-diamond substrates at low pressures (<760 torr) and low temperatures (<2000°C) by chemical vapour deposition (CVD) has been the subject of intense research in the last few years. The structural and the electrical properties of CVD diamond films grown on p-type 〈111〉 and high-resistivity (>100 kΩ-cm) 〈100〉 oriented silicon substrates by hot filament chemical vapour deposition technique are described in this review paper.     

Pulsed laser deposition of hydroxyapatite thin films

Hydroxyapatite is a bioactive ceramic material that mimics the mineral composition of natural bone. This material does not possess acceptable mechanical properties for use as a bulk biomaterial; however, it does demonstrate significant potential for use as a coating on metallic orthopaedic and dental prostheses. This paper reviews recent developments involving pulsed laser deposition of hydroxyapatite thin films for medical and dental applications. The structural, mechanical, and biological properties of hydroxyapatite thin films are described. In addition, future directions in pulsed laser deposition of hydroxyapatite thin films are discussed.     

Low-temperature deposition of iridium thin films by pulsed laser deposition

Extremely smooth iridium (Ir) thin films were deposited on Si(1 0 0) substrate at lower temperature than 300 °C by pulsed laser deposition (PLD) technique using Ir target in a vacuum atmosphere. The crystal orientation, surface morphology, and resistivity of the Ir thin films were systematically determined as a function of substrate temperature. Well-crystallized and single-phase Ir thin films with (1 1 1) preferred orientation were obtained at substrate temperature of 200-300 °C. The surface roughness increased with the increasing of substrate temperature. Likewise, the room-temperature resistivity of Ir thin films decreased with increasing substrate temperature, showing a low value of (10.7±0.1) μΩ cm at 300 °C.     

Characterization of diamond thin films deposited by a CO2 laser-assisted combustion-flame method

Diamond thin films were deposited by a CO₂ laser-assisted O₂/C₂H₂/C₂H₄ combustion-flame process. The effect of the deposition parameters, in particular the laser wavelength and power, on the film surface morphology, microstructure and phases present was the primary focus of the work. The laser power was set at 100, 400 and 800 W while the wavelength was varied and set at 10.591 µm in the untuned condition and set at 10.532 µm to resonantly match the CH₂-wagging vibrational mode of the C₂H₄ molecule when in the tuned condition. When the laser was coupled to the combustion flame during deposition the diamond film growth was enhanced as the lateral grain size increased from 1 µm to greater than 5 µm. The greatest increase in grain size occurred when the wavelength was in the tuned condition. Scanning transmission electron microscopy images from focused-ion beam cross-sectioned samples revealed a sub-layer of smaller grains less than 1 µm in size near the substrate surface at the lower laser powers and untuned wavelength. X-ray diffraction results showed a more intense Diamond (111) peak as the laser power increased from 100 to 800 W for the films deposited with the tuned laser wavelength. Micro-Raman spectra showed a diamond peak nearly twice as intense from the films with the tuned laser wavelength.     

Pulsed laser deposition of crystalline ZrC thin films

ZrC thin films were grown on Si substrates by the pulsed laser deposition (PLD) technique under various conditions. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), X-ray diffraction and reflectivity, spectroscopic ellipsometry, and four point probe measurements were used to characterize the properties of the deposited films. It has been found that crystalline films could be grown only by using laser fluences higher than 5 J/cm² and substrate temperatures in excess of 500 °C. For a fluence of 10 J/cm² and a substrate temperature of 700 °C, cubic ZrC films (a = 0.469 nm) exhibiting a (200)-texture were deposited under vacuum or low pressure C₂H₂ atmosphere. These films were smooth, with surface roughness values below 1.0 nm and mass densities around the tabulated value of 6.7 g/cm³. AES depth profiling investigations showed oxygen contamination around 7% in the bulk region. Despite the relatively high levels of oxygen contamination, the deposited ZrC films were very conductive. The use of a low C₂H₂ pressure atmosphere during deposition had a small beneficial effect on crystallinity and stoichiometry of the films.     

Pulsed laser deposition of Mn-Zn ferrite thin films

Mn-Zn ferrite thin films were deposited on sapphire substrates by pulsed laser deposition from sintered Mn_{1 – x}Zn _x Fe₂O₄ ceramic targets. A full stoichiometric transfer from targets to substrates was achieved. Magnetic inplane measurements in two perpendicular directions were carried out and the macromagnetic properties of films were determined. The hysteresis loops obtained are rectangular and the values of the coercive force, the saturation, and the remanent magnetization are comparable to the same parameters of the bulk Mn-Zn ferrite. The films were characterized using a vibrating sample magnetometer (VSM), a scanning electron microscope (SEM) and by X-ray photoelectron spectroscopy (XPS).     

Pulsed laser deposition of thin films on actively cooled substrates

The paper deals with a special arrangement of pulsed laser deposition (PLD) when the substrates were cooled at cryogenic temperatures by liquid nitrogen during the deposition process. Applied materials – zinc oxide and titanium dioxide – play an important role in current optoelectronics and sensor research and a comparative study of their behaviour in presented PLD arrangements were performed.Prepared films (deposited on different substrates: Si (100) and sapphire) were investigated in as-deposited states and their properties in dependence of deposition temperature were compared. Investigation by X-ray diffraction and Raman spectroscopy proved their amorphous structure. Subsequently, annealing under different temperatures (up to 800 °C) was applied and properties of modified structures were compared by using different analytical methods (scanning electron microscopy, X-ray diffraction, Raman spectroscopy, optical absorption spectroscopy and spectroscopic ellipsometry).Pulsed laser deposition with cryogenic cooling of substrates opens a promising way for deposition of materials in non-equilibrium state. Such structures differ significantly between their counterparts despite of identical chemical composition. Annealing of such amorphous structures provide special conditions for studying of their recrystallization dynamics and controlling of their properties.     

ZnO thin films prepared by pulsed laser deposition

Zinc oxide (ZnO) thin films were deposited on soda lime glass substrates by pulsed laser deposition (PLD) in an oxygen-reactive atmosphere. The structural, optical, and electrical properties of the as-prepared thin films were studied in dependence of substrate temperature and oxygen pressure. High quality polycrystalline ZnO films with hexagonal wurtzite structure were deposited at substrate temperatures of 100 and 300 °C. The RMS roughness of the deposited oxide films was found to be in the range 2-9 nm and was only slightly dependent on substrate temperature and oxygen pressure. Electrical measurements indicated a decrease of film resistivity with the increase of substrate temperature and the decrease of oxygen pressure. The ZnO films exhibited high transmittance of 90% and their energy band gap and thickness were in the range 3.26-3.30 eV and 256-627 nm, respectively.     

InGaZnO thin films grown by pulsed laser deposition

We fabricated InGaZnO (IGZO) ceramic target (In: Ga: Zn = 1: 1: 4 in atomic ratio) using solid-state reaction at ambient atmosphere, and deposited IGZO thin films on quartz glass at room temperature under various oxygen partial pressures using the pulsed laser deposition method. Influence of oxygen pressure on crystal structure, surface morphology, optical and electrical properties were investigated. It was found that all the films deposited at room temperature exhibit amorphous structure. On the other hand, the physical properties of the films like transparency, electron mobility, and free-electron concentration were found to be correlated to the oxygen pressure during the deposition and in turn to the possible oxygen vacancies or metallic interstitials in the films. The analysis of X-ray photoelectron spectra (XPS) of the films indicated that there are no metallic 3d states of In, Ga and Zn, suggesting that oxygen vacancies could be main defects that affect physical properties of the films.     

AlN薄膜的KrF准分子脉冲激光沉积

研究了采用脉冲激光沉积(PLD)技术在Si(100)衬底上AlN薄膜的制备及其性质。结果表明,衬底温度从室温到800℃的范围内,所得到的AlN薄膜为(002)择优取向的纤锌矿结构。随着衬底温度的升高,AlN薄膜从纳米晶结构转为多晶结构,同时表面微粗糙度上升。AlN晶粒呈柱状生长机制。     

ITO thin films deposited by advanced pulsed laser deposition

Indium tin oxide thin films were deposited by computer assisted advanced PLD method in order to obtain transparent, conductive and homogeneous films on a large area. The films were deposited on glass substrates. We studied the influence of the temperature (room temperature (RT)-180 °C), pressure (1-6 × 10^− 2 Torr), laser fluence (1-4 J/cm²) and wavelength (266-355 nm) on the film properties. The deposition rate, roughness, film structure, optical transmission, electrical conductivity measurements were done. We deposited uniform ITO thin films (thickness 100-600 nm, roughness 5-10 nm) between RT and 180 °C on a large area (5 × 5 cm²). The films have electrical resistivity of 8 × 10^− 4 Ω cm at RT, 5 × 10^− 4 Ω cm at 180 °C and an optical transmission in the visible range, around 89%.     

脉冲激光沉积法制备Pt薄膜的研究

采用脉冲激光沉积技术在(0001)取向的蓝宝石基片上外延生长了Pt单晶薄膜,研究了沉积温度和激光能量对Pt薄膜的晶体结构,表面形貌及电学性能的影响规律.X射线衍射(XRD)分析结果表明,在沉积温度650℃、激光脉冲频率1Hz和激光能量280mJ的条件下,制备得到的Pt(111)单晶薄膜,其(111)面ω摇摆曲线半高宽(FWHM)仅为0.068°.原子力显微镜(AFM)分析表明外延的Pt薄膜表面具有原子级平整度,其表面均方根粗糙度(RMS)约为1.776nm.四探针电阻测试结果显示薄膜方阻为1/962Ω/□,满足铁电薄膜的制备工艺对Pt底电极的要求.     

Process parameters optimization for laser deposition of highT c superconducting thin films on Si and other substrate materials

Thin films of Y-Ba-Cu-O superconductor have been deposited on different substrates by pulsed excimer laser ablation from a superconducting pellet. The dependence of various process parameters such as substrate temperature, laser energy density, oxygen partial pressure, applied bias field and cooling rates on the quality of the films has been studied.     

Structure of diamond and diamond like carbon thin films grown by hot-filament chemical vapour deposition technique

Micro-crystalline diamond (MCD) and diamond like carbon (DLC) thin films were deposited on silicon (100) substrates by hot-filament CVD process using a mixture of CH₄ and H₂ gases at substrate temperature between 400–800°C. The microstructure of the films were studied by X-ray diffraction and scanning electron microscopy. The low temperature deposited films were found to have a mixture of amorphous and crystalline phases. At high temperatures (> 750°C) only crystalline diamond phase was obtained. Scanning electron micrographs showed faceted microcrystals of sizes up to 2μm with fairly uniform size distribution. The structure of DLC films was studied by spectroscopic ellipsometry technique. An estimate of the amount of carbon bonds existing insp ² andsp ³ form was obtained by a specially developed modelling technique. The typical values ofsp ³/sp ² ratio in our films are between 1·88–8·02. Paper presented at the poster session of MRSI AGM VI, Kharagpur, 1995     

Oxidation of ZnO thin films during pulsed laser deposition process

Pulsed laser deposition of ZnO thin films, using KrF laser, is analysed. The films were deposited on (001) sapphire substrates at 400 °C, at two different oxygen pressures (0·3 and 0·4 mbar) and two different target–substrate distances (30 and 40 mm). It is observed that in order to obtain good quality in the photoluminescence of the films, associated with oxygen stoichiometry, it is needed to maximize the time during which the plasma remains in contact with the growing film (plasma residence time), which is achieved by selecting suitable combinations of oxygen pressures and target to substrate distances. It is also discussed that for the growth parameters used, the higher probability for ZnO films growth results from the oxidation of Zn deposited on the substrate and such process takes place during the time that the plasma is in contact with the substrate. Moreover, it is observed that maximizing the plasma residence time over the growing film reduces the rate of material deposition, favouring the surface diffusion of adatoms, which favours both Zn–O reaction and grain growth.     

Pulsed laser deposition of conductive indium tin oxide thin films

Thin indium tin oxide (ITO) films have been grown on quartz glass substrates by pulsed laser deposition. The influence of ablation target composition and deposition conditions on the growth rate, optical transmission spectra, and carrier mobility and concentration of the films has been examined. The average surface roughness of the ITO films grown at substrate temperatures above 300°C is 2 nm. The films grown at an oxygen partial pressure of 5 mTorr using ablation targets with Sn/(In + Sn) = 5% possess high transmission (85-95%) in the visible range and low resistivity (1.8 × 10⁻⁴ Ω cm).