Optical properties of hexagonal boron nitride thin films deposited by radio frequency bias magnetron sputtering

The optical properties of hexagonal boron nitride (h-BN) thin films were studied in this paper. The films were characterized by Fourier transform infrared spectroscopy, UV--visible transmittance and reflection spectra. h-BN thin films with a wide optical band gap E_g (5.86 eV for the as-deposited film and 5.97 eV for the annealed film) approaching h-BN single crystal were successfully prepared by radio frequency (RF) bias magnetron sputtering and post-deposition annealing at 970~K. The optical absorption behaviour of h-BN films accords with the typical optical absorption characteristics of amorphous materials when fitting is made by the Urbach tail model. The annealed film shows satisfactory structure stability. However, high temperature still has a significant effect on the optical absorption properties, refractive index n, and optical conductivity σ of h-BN thin films. The blue-shift of the optical absorption edge and the increase of E_g probably result from stress relaxation in the film under high temperatures. In addition, it is found that the refractive index clearly exhibits different trends in the visible and ultraviolet regions. Previous calculational results of optical conductivity of h-BN films are confirmed in our experimental results.     

射频磁控溅射法生长MgxZn1-xO薄膜的结构和光学特性

用射频磁控溅射法在80℃的衬底温度下制备出MgxZn1-xO(0≤x≤0.30)薄膜.x射线衍射(XRD)结果表明,MgxZn1-xO薄膜为单相六角纤锌矿结构,没有形成任何显著的MgO分离相,MgxZn1-xO薄膜的择优取向平行于与衬底垂直的c轴;c轴晶格常数随着Mg含量的增加逐渐减小.在MgxZn1-xO薄膜的光透射谱中出现锐利的吸收边,由透射谱估算出MgxZn1-xO薄膜的带隙宽度由3.32eV(x=0)线性地增加到3.96eV(x=0.30).     

Photocatalytic TiO2 thin films deposited on flexible substrates by radio frequency (RF) reactive magnetron sputtering

Titanium dioxide (TiO₂) thin films were deposited on flexible polycarbonate (PC) substrates by radio frequency (RF) reactive magnetron sputtering. The target was metallic titanium, argon was the plasma gas and oxygen was the reactive gas. Taguchi’s method, which uses an L₉ (3⁴) orthogonal array, signal-to-noise ratio and analysis of variance (ANOVA), was employed to study the performance of the deposition process. The effects of the deposition parameters on the structure, morphology and photocatalytic performance of the TiO₂ films were analyzed using scanning electron microscopy (SEM), X-ray diffraction, and UV-vis-NIR spectroscopy. Experiments varied RF power (50, 100, 150 W), deposition time (2, 3, 4 h), O₂/(Ar + O₂) argon/oxygen ratios (40, 60, 80%) and substrate temperatures (room, 80, 120 °C), to optimize the photoinduced decomposition of methylene blue (MB). The experimental results illustrate the effectiveness of this approach.     

Structural and photoluminescent properties of ZnO films deposited by radio frequency reactive sputtering

Zinc oxide films with c-axis preferred orientation were deposited on silicon (100) substrates by radio frequency (RF) reactive sputtering. The properties of the sam- ples were characterized by X-ray diffractometer, X-ray photoelectron spectroscopy and fluorescent-spectrophotometer. The effect of sputtering power and substrate temperature on the structural and photoluminescent (PL) properties of the ZnO films was investigated. The results indicated that when the sputtering power is 100 W and the substrate temperature is 300-400℃, it is suitable for the growth of high c-axis orientation and small strain ZnO films. A violet peak at about 380 nm and a blue band at about 430 nm were observed in the room temperature photolumines- cence spectra, and the origin of blue emission was investigated.     

衬底温度对反应磁控溅射W掺杂ZnO薄膜的微观结构及光电性能的影响

采用直流脉冲反应磁控溅射方法生长W掺杂ZnO（WZO）透明导电氧化物薄膜并研究了衬底温度对薄膜微观结构、组分、表面形貌以及光电性能的影响.实验结果表明,WZO薄膜具有良好的（002）晶面择优取向,且适当的衬底温度是制备优质WZO薄膜的关键因素.随着衬底温度升高,薄膜表面粗糙度先增大后减小;衬底温度较高时,薄膜的结构致密,结晶质量好,电子迁移率高.当衬底温度为325℃时,WZO薄膜获得最低电阻率9.25×10^-3Ω·cm,方块电阻为56.24Ω/□,迁移率为11.8 cm² V^-1·s^-1,其在可见光及近红外区域（400—1500 nm）范围的平均透过率达到85.7%.     

The properties of transparent conducting molybdenum-doped ZnO films grown by radio frequency magnetron sputtering

Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency(RF) magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10-4.cm,with a high Hall mobility of 30 cm2.V-1.s-1 and a carrier concentration of 2.3×1020 cm-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.     

Modulation of electrical and optical properties of gallium-doped ZnO films by radio frequency magnetron sputtering

Ga-doped ZnO(GZO) films are prepared on amorphous glass substrates at room temperature by radio frequency magnetron sputtering.The results reveal that the gallium doping efficiency,which will have an important influence on the electrical and optical properties of the film,can be governed greatly by the deposition pressure and film thickness.The position shifts of the ZnO(002) peaks in X-ray diffraction(XRD) measurements and the varied Hall mobility and carrier concentration confirms this result.The low Hall mobility is attributed to the grain boundary barrier scattering.The estimated height of barrier decreases with the increase of carrier concentration,and the trapping state density is nearly constant.According to defect formation energies and relevant chemical reactions,the photoluminescence(PL) peaks at 2.46 eV and 3.07 eV are attributed to oxygen vacancies and zinc vacancies,respectively.The substitution of more Ga atoms for Zn vacancies with the increase in film thickness is also confirmed by the PL spectrum.The obvious blueshift of the optical bandgap with an increase of carrier concentration is explained well by the Burstein-Moss(BM) effect.The bandgap difference between 3.18 eV and 3.37 eV,about 0.2 eV,is attributed to the metal-semiconductor transition.     

Characterization of ZnO thin films grown on various substrates by RF magnetron sputtering

In this study we investigated properties of ZnO thin films deposited on both oxygen-containing substrates and a substrate without oxygen content at various O₂/Ar reactant gas ratios. Deposition of ZnO on indium-tin oxide (ITO) resulted in the best crystallinity, whereas the least degree of crystallization was observed from ZnO deposited on glass. All the films were found to have compressive stress, which was relieved by annealing in O₂ environment. ZnO films deposited on glass revealed p-type conductivity when prepared at O₂/Ar ratio of 0.25 whereas those on SiN_x yielded p-type conductivity when prepared at O₂/Ar ratio of 4. In addition, shallower oxygen interstitial seemed to be found from films with better crystallinity. The largest shift in binding energy of Zn_2p3/2 was observed from ZnO prepared on glass at O₂/Ar ratio of 0.25, whereas that of O_1s was obtained from ZnO deposited on SiN_x at O₂/Ar ratio of 4. A model was proposed in terms of O₂ diffusion and hydrogen desorption in order to account for the observed property variations depending on substrates and O₂/Ar ratios.     

Microstructures and optical properties of Cu-doped ZnO films prepared by radio frequency reactive magnetron sputtering

Pure and Cu-doped ZnO (ZnO:Cu) thin films were deposited on glass substrates using radio frequency (RF) reactive magnetron sputtering. The effect of substrate temperature on the crystallization behavior and optical properties of the ZnO:Cu films have been studied. The crystal structures, surface morphology and optical properties of the films were systematically investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and a fluorescence spectrophotometer, respectively. The results indicated that ZnO films showed a stronger preferred orientation toward the c-axis and a more uniform grain size after Cu-doping. As for ZnO:Cu films, the full width at half maxima (FWHM) of (0 0 2) diffraction peaks decreased first and then increased, reaching a minimum of about 0.42° at 350 °C and the compressive stress of ZnO:Cu decreased gradually with the increase of substrate temperature. The photoluminescence (PL) spectra measured at room temperature revealed two blue and two green emissions. Intense blue-green luminescence was obtained from the sample deposited at higher substrate temperature. Finally, we discussed the influence of annealing temperature on the structural and optical properties of ZnO:Cu films. The quality of ZnO:Cu film was markedly improved and the intensity of blue peak (∼485 nm) and green peak (∼527 nm) increased noticeably after annealing. The origin of these emissions was discussed.     

Optical properties and structures of silver thin films deposited by magnetron sputtering with different thicknesses

A series of thin Ag films with different thicknesses grown under identical conditions are analyzed by means of spectrophotometer. From these measurements the values of refractive index and extinction coefficient are calculated. The films are deposited onto BK7 glass substrates by direct current (DC) magnetron sputtering. It is found that the optical properties of the Ag films can be affected by films thickness.Below critical thickness of 17 nm, which is the thickness at which Ag films form continuous films, the optical properties and constants vary significantly with thickness increasing and then tend to a stable value up to about 40 nm. At the same time, X-ray diffraction measurement is carried out to examine the microstructure evolution of Ag films as a function of films thickness. The relation between optical properties and microstructure is discussed.     

射频磁控溅射法生长MgxZn1-xO薄膜的结构和光学特性

用射频磁控溅射法在80℃的衬底温度下制备出Mg_xZn_1-xO(0≤x ≤030)薄膜.x射线 衍射(XRD)结果表明，Mg_xZn_1-xO薄膜为单相六角纤锌矿结构， 没有形成任何显著 的MgO分离相，Mg_xZn_1-xO薄膜的择优取向平行于与衬底垂直的 c轴；c轴晶格常数随着Mg含量的增加逐渐减小.在Mg_xZn_1-xO薄膜的光透射谱中出现 锐利的吸收边，由透 射谱估算出Mg_xZn_1-xO薄膜的带隙宽度由332eV(x=0)线性地 增加到396eV(x=030). 关键词： xZn_1-xO薄膜')" href="#">Mg_xZn_1-xO薄膜 射频磁控溅射 Mg含量     

Study on oxygen source and its effect on film properties of ZnO deposited by radio frequency magnetron sputtering

The structural and optical properties of ZnO thin films deposited at various oxygen partial pressure and rf-power of rf magnetron sputtering were investigated. The sputtered ZnO films are mainly formed with the oxygen which was supplied from a sputtering gas; therefore the film stoichiometry can be controlled by the oxygen partial pressure and rf-power. From photoluminescence study, it was found that the wide emission band above 550 nm was observed due to an increase of oxygen vacancies when the ZnO film changed from O-rich to Zn-rich. The chemical stoichiometry of the film will help us to understand the formation mechanism of intrinsic defects in ZnO films.     

The influence of titanium on the properties of zinc oxide films deposited by radio frequency magnetron sputtering

TiO₂-doped zinc oxide thin films were deposited on glass substrates by radio frequency (RF) magnetron sputtering with TiO₂-doped ZnO targets in an argon atmosphere. The structural properties of TiO₂-doped ZnO films doped with different TiO₂ contents were investigated. The experimental results show that polycrystalline TiO₂-doped ZnO films had the (0 0 2) preferred orientation. The deposition parameters such as the working pressure and substrate temperature of TiO₂-doped ZnO films were also investigated. The crystalline structure of the TiO₂-doped ZnO films gradually improved as the working pressure was lowered and the substrate temperature was raised. The lowest electrical resistivity for the TiO₂-doped ZnO films was obtained when the Ti addition was 1.34 wt%; its value was 2.50 × 10⁻³ Ω cm, smaller than that found in previous studies. The transmittance of the TiO₂-doped ZnO films in the visible wavelength range was more than 80%. The optical energy gap was related to the carrier concentration, and was in the range of 3.30-3.48 eV.     

Preparation of boron carbon nitride thin films by radio frequency magnetron sputtering

Boron carbon nitride films were deposited by radio frequency magnetron sputtering using a composite target consisting of h-BN and graphite in an Ar-N₂ gas mixture. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results suggest that the films are atomic-level hybrids composed of B, C and N atoms. The boron carbon nitride films prepared in the present experiment have a disordered structure. The sputtering power varied from 80 W to 130 W. This sputtering power was shown to have regular effect on the composition of boron carbon nitride films. The samples deposited at 80 W and 130 W are close to the stoichiometry of BC₃N. The sample deposited at 110 W is close to the stoichiometry of BCN. The samples deposited at 100 W and 120 W approach to BC₂N. It is very significant for us to synthesize boron carbon nitride compound with controllable composition by changing the sputtering power.     

Optical and electrical properties of thin NiO films deposited by reactive magnetron sputtering and spray pyrolysis

Thin NiO films are deposited by reactive magnetron sputtering and spray pyrolysis. The main optical constants, i.e., refractive index n(λ), absorption coefficient α(λ), extinction coefficient k(λ), and thickness d, are determined. The temperature dependence of the resistance of thin films is found, and the activation energy of films deposited by different methods is determined.     

直流磁控溅射Cr-Cr2O3复合金属陶瓷薄膜光学特性研究

采用直流反应磁控溅射技术在不同靶电流条件下制备了Cr-Cr2O3金属陶瓷薄膜,并利用椭偏仪测量了薄膜的光学常数.采用修正的M-G(Maxwell-Gannett)理论对不同靶电流条件下沉积的Cr-Cr2O3金属陶瓷薄膜的光学常数进行了理论计算,并将理论计算结果与实验数据进行了比较.结果表明:随着靶电流的增加,膜层中金属微粒体积百分比增加,金属微粒的平均半径随之增加,且金属微粒逐渐趋于扁圆形,理论计算结果与实验结果吻合较好.     

Effects of sapphire substrates surface treatment on the ZnO thin films grown by magnetron sputtering

The surface treatment effects of sapphire substrate on the ZnO thin films grown by magnetron sputtering were studied. The sapphire substrates properties have been investigated by means of atomic force microscopy (AFM) and X-ray diffraction rocking curves (XRCs). The results show that sapphire substrate surfaces have the best quality by CMP with subsequent chemical etching. The surface treatment effects of sapphire substrate on the ZnO thin films were examined by X-ray diffraction (XRD) and photoluminescence (PL) measurements. Results show that the intensity of (0 0 2) diffraction peak of ZnO thin films on sapphire substrates treated by CMP with subsequent chemical etching was strongest, FWHM of (0 0 2) diffraction peak is the narrowest and the intensity of UV peak of PL spectrum is strongest, indicating surface treatment on sapphire substrate preparation may improve ZnO thin films crystal quality and photoluminescent property.     

Magnetic anisotropy properties of CoZrNb thin films deposited on PET substrate by magnetron sputtering

Soft magnetism and magnetic anisotropy properties of CoZrNb thin films deposited on polyethylene terephthalate (PET) substrate by magnetron sputtering were investigated. As the film thickness increases, the coercivity of films decreases from 7 to 4 Oe. It exhibits an in-plane uniaxial magnetic anisotropy as the thickness of CoZrNb thin films increases. An easy axis is observed in CoZrNb films along the direction transverse to the rolling direction of the polymer web.     

GeC薄膜的射频磁控反应溅射制备及性质

用射频磁控反应溅射法在ZnS衬底上制备了GeC薄膜,研究了工艺参数对Ge靶溅射及GeC薄膜红外透射性能的影响.衬底温度较低时GeC薄膜中含有H,形成了CH₂,CH₃,Ge-CH₃等,使薄膜产生红外吸收;随衬底温度升高,薄膜红外吸收明显减小.靶基距、射频功率、Ar:CH₄气体流量比、总气压对靶面中毒及溅射影响较大,但对GeC薄膜红外吸收影响较小.靶面中毒严重时,所制备无氢GeC薄膜附着性能差,随靶中毒减弱薄膜附着性能变好.优化工艺后,在ZnS衬底上制备了附着性能良好的无氢GeC薄膜,其折射率约为1.78,薄膜中C的含量比Ge的大,二者主要形成了C—Ge键.所制备的GeC/GaP红外增透保护膜系对ZnS衬底有良好的增透效果. 关键词： GeC薄膜 红外透射光谱 射频磁控溅射 XPS     

Influence of substrate temperature on the optical and piezoelectric properties of ZnO thin films deposited by rf magnetron sputtering

In this study, ZnO thin films were fabricated using the rf magnetron sputtering method and their piezoelectrical and optical characteristics were investigated for various substrate temperatures. The ZnO thin film has the largest crystallization orientation for the (0 0 2) peak and the smallest FWHM value of 0.56° at a substrate temperature of 200 °C. The surface morphology shows a relatively dense surface structure at 200 °C compared to the other substrate temperatures. The surface roughness shows the smallest of 1.6 nm at a substrate temperature of 200 °C. The piezoelectric constant of the ZnO thin film measured using the pneumatic loading method (PLM) has a maximum value of 11.9 pC/N at a substrate temperature of 200 °C. The transmittance of the ZnO thin film measured using spectrophotometry with various substrate temperatures ranged from 75 to 93% in the visible light region. By fitting the refractive index from the transmittance to the Sellmeir dispersion relation, we can predict the refractive index of the ZnO thin film according to the wavelength. In the visible light range, the refraction index of the ZnO thin film deposited at a substrate temperature of 200 °C is the range of 1.88-2.08.