Optical and electrical properties of SnO2 films prepared by chemical vapour deposition

Transparent and conducting SnO₂ films are prepared at 500°C on quartz substrates by chemical vapour deposition technique, involving oxidation of SnCl₂. The effect of oxygen gas flow rate on the properties of SnO₂ films is reported. Oxygen with a flow rate from 0·8–1·35 lmin⁻¹ was used as both carrier and oxidizing gas. Electrical and optical properties are studied for 150 nm thick films. The films obtained have a resistivity between 1·72 × 10⁻³ and 4·95 × 10⁻³ ohm cm and the average transmission in the visible region ranges 86–90%. The performance of these films was checked and the maximum figure of merit value of 2·03 × 10⁻³ ohm⁻¹ was obtained with the films deposited at the flow rate of 1·16 lmin⁻¹.     

Grain growth of copper films prepared by chemical vapour deposition

Copper films having thickness 600 nm were prepared on TiN using chemical vapour deposition (CVD). The deposited films were annealed at various temperatures (350–550°C) in Ar and H₂(10%)-Ar ambients. The changes in the grain size of the films upon annealing were investigated. Annealing in an H₂(10%)-Ar ambient produced normal grain growth; annealing in an Ar ambient caused grain growth to stop at 550°C. The grain size followed a monomodal distribution and the mean size increased in proportion to the square root of the annealing time, indicating the curvature of the grain is the main driving force for grain growth. Upon annealing at 450°C for 30 min in an H₂(10%)-Ar ambient, the average grain size of the film increased from 122 nm to 219 nm, and the resistivity decreased from 2.35 μΩ cm to 2.12 μΩ cm at a film thickness of 600 nm. This revised version was published online in July 2006 with corrections to the Cover Date.     

Undoped and indium-doped CdS films prepared by chemical vapour deposition

Undoped and In-doped films of CdS were deposited at different temperatures by the chemical vapour deposition technique on glass and In-coated (30 nm) glass, respectively. Both kinds of film present a columnar microstructure, low porosity and good adherence to the substrate. The doped films have higher electron mobility values compared with the undoped ones. Shifts in the transmission spectra (Moss-Burstein effect) were observed with increased doping. Small crystals grew over the doped films during the deposition stage, mainly at the higher substrate temperatures.     

脉冲激光沉积氮化铝薄膜的电学性能研究

采用脉冲激光沉积(PLD)技术在硅片上合成了AlN薄膜.X射线衍射(XRD)结果证实制备的AlN薄膜具有(002)择优取向的六方纤锌矿晶体结构,并且结晶质量随Si衬底温度的提高而改善.电流-电压(I-V)、电容-电压(C-V)、极化曲线结果表明室温生长的AlN薄膜的击穿场强约2.5MV/cm,同时呈现明显的极化现象(类铁电),对应矫顽场强为150kV/cm,剩余极化为0.002C/m2.晶态AlN存在较强的自发极化,薄膜中可动电荷密度高,据此提出了动态电荷模型,指出较大的AlN薄膜极化回线是由于可动电荷在电场中的再分布形成的,因而有别于铁电材料.     

Conductive indium-doped zinc oxide films prepared by atmospheric-pressure chemical vapour deposition

Abstracts are not published in this journal     

Nickel thin films prepared by chemical vapour deposition from nickel acetylacetonate

Nickel thin films were prepared by a low-temperature atmospheric-pressure chemical vapour deposition method. The raw material was nickel acetylacetonate. At a reaction temperature above 250 °C, polycrystalline nickel films can be obtained by hydrogen reduction of the raw material. The resistivity (8.1–13.3 cm) of the film was close to that of bulk nickel.     

Copper thin films prepared by chemical vapour deposition from copper dipivalylmethanate

Copper thin films were prepared by a low-temperature atmospheric-pressure chemical vapour deposition method. The raw material was copper dipivalylmethanate which is volatile and thermally stable. At a reaction temperature above 220°C, polycrystalline copper films can be obtained by hydrogen reduction of the raw material. The resistivity of the film was in the range 1.7–2.7 cm.     

Crystalline carbon nitride films prepared by microwave plasma chemical vapour deposition

Crystalline carbon nitride films have been synthesized on Si (100) substrates by a microwave plasma chemical vapour deposition technique, using mixture of N₂, CH₄ and H₂ as precursor. Scanning electron microscopy shows that the films consisted of hexagonal bars, tetragonal bars, rhombohedral bars, in which the bigger bar is about 20 μm long and 6 μm wide. The X-ray photoelectron spectroscopy suggests that nitrogen and carbon in the films are bonded through hybridized sp² and sp³ configurations. The x-ray diffraction pattern indicates that the films are composed of α-, β-, pseudocubic and cubic C₃N₄ phase and an unidentified phase. Raman spectra also support the existence of α- and β-C₃N₄ phases. Vickers microhardness of about 41.9 GPa measured for the films.     

Structure and morphology of titanium nitride films deposited by laser-induced chemical vapour deposition

Results on the deposition of titanium nitride on AISI M2 tool steel-type substrates by pyrolytic laser chemical vapour deposition are reported. Spots of TiN were deposited from a gas mixture of TiCl₄, nitrogen and hydrogen using a continuous wave quasi-TEM_oo CO₂ laser beam. The morphology and the structure of the deposited material were investigated by optical microscopy, scanning electron microscopy and X-ray diffraction. The chemical composition was studied with a scanning electron microscope with an energy dispersive spectrometer, and with an electron probe microanalyser. The topography of the coating was analysed with a stylus profilometer and different thickness profiles were measured depending on the laser-power densities and irradiation times. The morphology of the films showed a strong dependence on the laser-power density, interaction time and partial pressure of TiCl₄.     

Growth and characterization of tin oxide films prepared by chemical vapour deposition

Undoped tin oxide films have been prepared by a chemical vapour deposition technique. The effect of different deposition parameters on the sheet resistance of the films has been studied. Films are highly transparent (about 90%) in the visible region, have a quite low sheet resistance (25 Ω/□) and have reproducible properties. X-ray diffraction shows the structure to be polycrystalline with a grain size of about 570 Å. The preferred orientation is (101) for the films deposited at substrate temperatures up to 350 °C, after which the preferred orientation changes to (200). The electrical properties of the films also exhibit a change at this deposition temperature. Direct and indirect band gaps are calculated to be 3.93 eV and 2.53 eV respectively. Degradation of the films with time has also been studied. The figure of merit = T¹⁰/R_sh (9.45 × 10^-3Ω^-1 at 0.66 μm) obtained is the highest amongst the values reported for undoped tin oxide films.     

Thin tin oxide films of low conductivity prepared by chemical vapour deposition

Homogeneous SnO₂ films were produced from dibutylin diacetate by chemical vapour deposition at rates of 10–30 nm min^?1. The films obtained had conductiveties between 3 and 25Ω^?1 cm^?1 and they showed a high quantum efficiency for dye sensitization. Under various conditions a linear dependence of the thickness and resistivity of the films on deposition time was observed. The transmission of most of the films was greater than 90%. SnO₂ films with a thickness of more than 500 nm exhibit absorption. The refractive index of these films, as determined by UV-visible interference measurements in reflection, is between 1.8 and 2.2 in the wavelength range 300–860 nm and agrees well with the refractive index determined from interference microscope measurements. Heat treatment of the films exposed to air lowers their conductivity and refractive indices.     

Process optimization and related material properties of silicon films produced by laser-induced chemical vapour deposition from silane

Laser-induced chemical vapour deposition of silicon films on SiO₂/Si (1 0 0) and Si (1 0 0) substrates was studied using ArF laser irradiation of silane/argon gas mixture in parallel to the substrate. The optimal deposition conditions were specified by examination of film morphology at a wide range of irradiation and process parameters. At optimal conditions, specular films were obtained with no powder formation. The effect of deposition parameters, such as laser energy and repetition rate, on the deposition rate and the related film quality, was investigated.     

Multi-phase structured silicon carbon nitride thin films prepared by hot-wire chemical vapour deposition

In this work, Silicon Carbon Nitride (Si-C-N) thin films were deposited by Hot Wire Chemical Vapour Deposition (HWCVD) technique from a gas mixture of silane (SiH₄), methane (CH₄) and nitrogen (N₂). Six sets of Si-C-N thin films were produced and studied. The component gas flow rate ratio (SiH₄:CH₄:N₂) was kept constant for all film samples. The total gas flow-rate (SiH₄ + CH₄ + N₂) was changed for each set of films resulting in different total gas pressure which represented the deposition pressure for each of these films ranging from 40 to 100 Pa. The effects of deposition pressure on the chemical bonding, elemental composition and optical properties of the Si-C-N were studied using Fourier transform infrared (FTIR) spectroscopy, Auger Electron Spectroscopy (AES) and optical transmission spectroscopy respectively. This work shows that the films are silicon rich and multi-phase in structure showing significant presence of hydrogenated amorphous silicon (a-Si:H) phase, amorphous silicon carbide (a-SiC), and amorphous silicon nitride (a-SiN) phases with Si-C being the most dominant. Below 85 Pa, carbon content is low, and the films are more a-Si:H like. At 85 Pa and above, the films become more Si-C like as carbon content is much higher and carbon incorporation influences the optical properties of the films. The properties clearly indicated that the films underwent a transition between two dominant phases and were dependent on pressure.     

化学水浴法制备ZnS薄膜光学性能

利用薄膜分析系统测量不同沉积时间制备的ZnS薄膜透射谱,通过分析薄膜透射谱,来确定ZnS薄膜光学常数和禁带宽度.实验结果表明,在线性生长阶段,薄膜的沉积速率大约为1 nm/min,具有很好的线性关系,沉积0.5 h的ZnS薄膜在可见光范围内光透过率为82%左右.     

Thermal analysis of hydrogenated amorphous carbon films prepared by plasma enhanced chemical vapour deposition

Hydrogenated amorphous carbon (a-C∶H) films were produced from propane and argon by an inductively coupled radio frequency (r.f.) glow discharge process under a particular deposition condition. Thermal analysis for the deposit by GC, DSC, DTA, and TG gave information for the structural changes upon heating. Most C-H vibration spectra disappeared by heating up to 600 °C. The gas desorption began above 300 °C and reached maxima above 650 °C with several peaks. The desorption reaction was endothermic. Up to 600 °C the desorbed gases was not the hydrogen. The large weight change was observed without the thickness reduction. The weight change rate was maximum at 480 °C. Hydrocarbons are believed to desorb below 600 °C. A hydrocarbon desorption model is suggested. Hydrocarbons are formed in the inner surface of a microvoid and effuse out through the interconnected microvoids in the column boundaries. The proposed desorption reaction is also endothermic.     

Orientation of the BSCCO films prepared by low-pressure single-aerosol source metallorganic chemical vapour deposition

Thin films (0.7–0.8 μm) of Bi₂Sr₂CaCu₂O_x were deposited by low-pressure metallorganic chemical vapour deposition with a single aerosol source. The influence of the deposition parameters on the orientation of the films was studied. It was established that low deposition rate, high deposition temperature and the presence of the liquid phase resulted in films with predominant c-orientation.