Texture enhancement of Al films on Ti underlayers by radio-frequency bias sputtering

The influence of sputtering pressure and radio-frequency (RF) bias power on the texture of Al/Ti thin films has been investigated. The Al/Ti thin films were deposited sequentially onto thermally oxidized Si wafers in a direct-current (DC) magnetron system. The RF bias was applied during Ti deposition. The texture of Al thin films was quantified by θ–2θ scans and rocking curves of x-ray diffraction (XRD). The Al thin films deposited on bias-sputtered Ti underlayers showed an epitaxial growth and strong (111) texture. The Al (111) texture improved with decreasing sputtering pressure and increasing RF-bias power. The Al/Ti texture was also enhanced when the SiO₂/Si substrate surface was RF plasma cleaned prior to Ti deposition. The Al (111) texture was closely related to Ti (0002) texture. The mechanism of Ti-texture improvement by applying bias sputtering was explained based on the ion-bombardment effect.     

Deposition and characterization of molybdenum thin films using dc-plasma magnetron sputtering

Molebdenum (Mo) thin films were deposited on well-cleaned soda-lime glass substrates using DC-plasma magnetron sputtering. In the design of experiment deposition was optimized for maximum beneficial characteristics by monitoring effect of process variables such as deposition power (100–200 W). Their electrical, structural and morphological properties were analyzed to study the effect of these variables. The electrical resistivity of Mo thin films could be reduced by increasing deposition power. Within the range of analyzed deposition power, Mo thin films showed a mono crystalline nature and the crystallites were found to have an orientation along [110] direction. The surface morphology of thin films showed that a highly dense micro structure has been obtained. The surface roughness of films increased with deposition power. The adhesion of Mo thin films could be improved by increasing the deposition power. Atomic force microscopy was used for the topographical study of the films and to determine the roughness of the films. X-ray diffractrometer and scanning electron microscopy analysis were used to investigate the crystallinity and surface morphology of the films. Hall effect measurement system was used to find resistivity, carrier mobility and carrier density of deposited films. The adhesion test was performed using scotch hatch tape adhesion test. Mo thin films prepared at deposition power of 200 W, substrate temperature of 23°C and Ar pressure of 0.0123 mbar exhibited a mono crystalline structure with an orientation along (110) direction, thickness of ～550 nm and electrical resistivity value of 0.57 × 10^?4 Ω cm.     

Investigation into the influence of direct current (DC) power in the magnetron sputtering process on the copper crystallite size

This paper discusses the influence of direct current (DC) power in the magnetron sputtering process on the crystallite size of the copper (Cu) thin films deposited on p-type silicon substrate at room temperature. X-ray diffraction (XRD) and Karl Suss four-point probe were employed to study the film crystallinity and conductivity, respectively. From the analysis on the XRD patterns, high DC power enhances the Cu film crystallinity with larger crystallite size, which is deduced using Sherrer's formula. The behavior of the electrical property of the Cu films complies with the trend of the film crystallinity with DC power, in which the film conductivity increases with increasing DC power. We attribute these phenomena to the enhanced surface diffusion mechanism of the adatom during the sputtering deposition process, which improves the microstructure of the Cu film.     

Photoelectric properties of ITO thin films deposited by DC magnetron sputtering

As anti-reflecting thin films and transparent electrodes of solar cells,indium tin oxide（ITO） thin films were prepared on glass substrates by DC magnetron sputtering process.The main sputtering conditions were sputtering power,substrate temperature and work pressure.The influence of the above sputtering conditions on the transmittance and conductivity of the deposited ITO films was investigated.The experimental results show that, the transmittance and the resistivity decrease as the sputtering power increases from 30 to 90 W.When the substrate temperature increases from 25 to 150℃,the transmittance increases slightly whereas the resistivity decreases.As the work pressure increases from 0.4 to 2.0 Pa,the transmittance decreases and the resistivity increases.When the sputtering power,substrate temperature and work pressure are 30 W,150℃,0.4 Pa respectively,the ITO thin films exhibit good electrical and optical properties,with resistivity below 10^-4Ω·cm and the transmittance in the visible wave band beyond 80%.Therefore,the ITO thin films are suitable as transparent electrodes of solar cells.     

溅射工艺参数对BST薄膜介电常数的影响

采用射频磁控溅射法在ITO玻璃基片上制备了约700nm的Ba0.5Sr0.5Ti03(BST)薄膜。研究了溅射功率、气压、ψ[O2/(Ar+O2)]比和基片温度对εr的影响,获得各种溅射条件下的薄膜的εr为250~310。提出了较优的工艺,即本底真空1.5×10–3Pa、靶基距6.2cm、功率300W、气压1.8Pa、ψ[O2/(Ar+O2)]为30%和衬底温度500℃,并研究了薄膜的晶相、组成和形貌。     

Effect of processing parameter on structural,optical and electrical properties of photovoltaic chalcogenide nanostructured RF magnetron sputtered thin absorbing films

The aim of this work was to develop high quality of CuIn_1−xGa_xSe₂ thin absorbing films with x (Ga/In+Ga)<0.3 by sputtering without selenization process. CuIn_0.8Ga_0.2Se₂ (CIGS) thin absorbing films were deposited on soda lime glass substrate by RF magnetron sputtering using single quaternary chalcogenide (CIGS) target. The effect of substrate temperature, sputtering power & working pressure on structural, morphological, optical and electrical properties of deposited films were studied. CIGS thin films were characterised by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), Energy dispersive X-ray spectroscopy (EDAX), Atomic force microscopy (AFM), UV–vis–NIR spectroscopy and four probe methods. It was observed that microstructure, surface morphology, elemental composition, transmittance as well as conductivity of thin films were strongly dependent on deposition parameters. The optimum parameters for CIGS thin films were obtained at a power 100 W, pressure 5 mT and substrate temperature 500 °C. XRD revealed that thin film deposited at above said parameters was polycrystalline in nature with larger crystallite size (32 nm) and low dislocation density (0.97×10¹⁵ lines m⁻²). The deposited film also showed preferred orientation along (112) plane. The morphology of the film depicted by FE-SEM was compact and uniform without any micro cracks and pits. The deposited film exhibited good stoichiometry (Ga/In+Ga=0.19 and In/In+Ga=0.8) with desired Cu/In+Ga ratio (0.92), which is essential for high efficiency solar cells. Transmittance of deposited film was found to be very low (1.09%). The absorption coefficient of film was ~10⁵ cm⁻¹ for high energy photon. The band gap of CIGS thin film evaluated from transmission data was found to be 1.13 eV which is optimum for solar cell application. The electrical conductivity (7.87 Ω⁻¹ cm⁻¹) of deposited CIGS thin film at optimum parameters was also high enough for practical purpose.     

Structure and properties of Al-1%Si thin films on Si as a function of gas impurities during DC magnetron-sputtered deposition

Thin films of Al-l%Si were sputter deposited on Si under a variety of pressures of atmospheric impurity gases. The effect of the impurity gases (oxygen, nitrogen, and water), and deposition temperature (15° and 300° C), on the microstructure and properties of the aluminum thin films were studied. The gas pressures introduced during deposition varied from 5 × 10^s−6 Torr (6.7 × 10^s−4 Pa) to 1 × 10^s-10 Torr (1 × 10^s−8 Pa). The thin films were investigated by transmission electron microscopy and were found to have a columnar microstructure with an even distribution of silicon precipitates. Both the grain size and silicon precipitate size increased at the higher deposition temperature. A smaller grain size was found in samples that were deposited under the higher impurity gas pressures tested. The specular reflectance of the films was found to be dependent upon the amount of impurity gases present during deposition, the greater the partial pressure the greater the surface roughness. This study also investigated the possibility of using a Resistivity Ratio (RR) measurement to evaluate the grain size of the Al thin films. It has been previously observed that a small Al grain size has poor electromigration resistance. This study found that the correlation between Al grain size and RR values was good indicating that RR tests may be used as a quick, non-destructive measure of film quality.     

直流磁控溅射工艺参数对β-FeSi_2薄膜性能的影响

采用室温直流磁控溅射Fe-Si组合靶的方法,经过后续Ar气氛围退火,在单晶Si(111)衬底上生长β-FeSi2薄膜。研究了溅射功率、工作气压、Ar气流量、沉积时间等工艺参数对β-FeSi2薄膜结构特性及电学特性的影响,通过Raman、Hall、X射线衍射(XRD)等测试对其性能进行表征,对工艺参数进行了优化,在溅射功率为80W、工作气压为1.3Pa和Ar气流量为35SCCM时溅射沉积Fe-Si薄膜,不仅可以得到单一相的β-FeSi2,而且薄膜结晶质量较好。最终,在上述实验条件下制备得到的未掺杂的β-FeSi2薄膜是n型导电的,β-FeSi2薄膜中载流子浓度约为3.3×1016cm-3,迁移率为381cm2/Vs。     

Deposition of polycrystalline AIN thin films by coherent magnetron sputtering at temperatures <80°C

A1N thin films were reactively deposited onto Al layers on negatively biased glass and Si substrates at temperatures <80°C by coherent magnetron sputtering. The low temperature deposition of the films without substrate heating was achieved by increasing the target-to-substrate distance, and therefore the heating effect of the plasma is relieved. The microstructure and morphology of the films deposited at different bias voltage and target-to-substrate distance were investigated. The films are amorphous when the target is far from the substrate for a bias voltage up to −320V. When the target-to-substrate distance is decreased to 17 cm a preferred (002) orientation of AIN films is observed at a bias voltage of −240 V. Additionally, the deposited films have specular reflectance and no voids can be observed. This low temperature technique can be used for applications in acoustic wave devices due to the improved homogeneity of the films and step coverage.     

低真空射频反应溅射Al2O3薄膜

用射频反应溅射法在硅片上制备Ａｌ２Ｏ３薄膜，在１０Ｐａ的低真空中和以适当比例混合的氩气和氧气中反应溅射以使薄膜充气氧化并保持一定的沉积速率，从而得到了理想配比和折射率为１．６０￣１．６５的Ａｌ２Ｏ３非晶薄膜。     

溅射沉积功率对PZT薄膜的组分、结构和性能的影响

用射频(RF)溅射法在镀LaNiO3(LNO)底电极的Si片上沉积PbZr0.52 Ti0.48 O3(PZT)铁电薄膜，沉积过程中基底温度为370℃，然后在大气环境中对沉积的PZT薄膜样品进行快速热退火处理(650℃，5min)．用电感耦合等离子体发射光谱(ICP-AES)测量其组分，X射线衍射(XRD)分析PZT薄膜的结晶结构和取向，扫描电子显微镜(SEM)分析薄膜的表面形貌和微结果，RT66A标准铁电综合测试系统分析Pt／PZT／LNO电容器的铁电与介电特性，结果表明，PZT薄膜的组分、结构和性能都与溅射沉积功率有关．     

Effect of sputtering power on optical properties of prepared TiO2 thin films by thermal oxidation of sputtered Ti layers

In this research, TiO₂ thin films prepared via thermal oxidation of Ti layers were deposited by RF-magnetron sputtering method at three different sputtering powers. The effects of sputtering power on structure, surface and optical properties of TiO₂ thin films grown on glass substrate were studied by X-ray diffraction (XRD), atomic force microscopic (AFM) and UV–visible spectrophotometer. The results reveal that, the structure of layers is changed from amorphous to crystalline at anatase phase by thermal oxidation of deposited Ti layers and rutile phase is formed when sputtering power is increased. The optical parameters: absorption coefficient, dielectric constants, extinction coefficient, refractive index, optical conductivity and dissipation factor are decreased with increase in sputtering power, but increase in optical band gap is observed. The roughness of thin films surface is affected by changes in sputtering power which is obtained by AFM images.     

RF磁控溅射制备AZO透明导电薄膜及其性能

室温下采用RF磁控溅射技术在石英衬底E制备了多晶ZnO:Al(AZO)透明导电薄膜,通过XRD,AFM,AES,Hall效应及透射光谱等测试研究了RF溅射功率、氩气压强对薄膜的结构、电学和光学性能的影响.分析表明:在最优条件下(溅射功率为250W,氩气压强为1.2Pa时),180nm AZO薄膜的电阻率为2.68×10-3 Ω·cm,可见光区平均透射率为90%,适合作为发光二极管和太阳能电池的透明电极.所制备的AZO薄膜具有c轴择优取向,晶粒问界中的O原子吸附是限制薄膜电学性能的主要因素.     

射频溅射功率对非晶Zn-Sn-O薄膜性能的影响

使用射频磁控溅射法,基于不同溅射功率(58、79、116、148和171W)条件在玻璃基底上室温制备了Zn-Sn-O(ZTO)薄膜,并探讨了溅射功率对薄膜的结构、电学性能和光学性能的影响。结果表明,提高溅射功率有助于提升薄膜的沉积速率;XRD分析表明不同溅射功率条件下制备的ZTO薄膜均具备稳定的非晶结构;随着溅射功率的增加,薄膜的电阻率下降,光学吸收边“红移”(光学禁带宽度从3.77eV减小到3.62eV);整体来看,在58~148W溅射功率范围内制备的ZTO薄膜具备较好的可见光透明性,其在380~780nm可见光范围内的平均透过率均超过85%。     

RF溅射ZnO薄膜工艺与结构研究

通过RF磁控溅射在Si(100)基片上制备了ZnO薄膜,并研究了磁控溅射中各生长参数,如衬底温度、氧分压及后处理工艺等因素对ZnO薄膜微结构、表面形貌与结晶取向的影响。结果表明:溅射温度和氧分压对薄膜的微结构与择优取向有很大的影响,并对不同的溅射工艺进行了分析比较,从而确定了最佳溅射及后处理条件:RF溅射温度小于300℃,功率为50W,ψ(Ar:O2)为20:5,退火温度550~600℃,并获得了c轴择优取向的ZnO薄膜。     

Pulsed laser deposition and processing of wide band gap semiconductors and related materials

The present work describes the novel, relatively simple, and efficient technique of pulsed laser deposition for rapid prototyping of thin films and multi-layer heterostructures of wide band gap semiconductors and related materials. In this method, a KrF pulsed excimer laser is used for ablation of polycrystalline, stoichiometric targets of wide band gap materials. Upon laser absorption by the target surface, a strong plasm a plume is produced which then condenses onto the substrate, kept at a suitable distance from the target surface. We have optimized the processing parameters such as laser fluence, substrate temperature, background gas pressure, target to substrate distance, and pulse repetition rate for the growth of high quality crstalline thin films and heterostructures. The films have been characterized by x-ray diffraction, Rutherford backscattering and ion channeling spectrometry, high resolution transmission electron microscopy, atomic force microscopy, ultraviolet (UV)-visible spectroscopy, cathodoluminescence, and electrical transport measurements. We show that high quality AlN and GaN thin films can be grown by pulsed laser deposition at relatively lower substrate temperatures (750–800°C) than those employed in metal organic chemical vapor deposition (MOCVD), (1000–1100°C), an alternative growth method. The pulsed laser deposited GaN films (∼0.5 μm thick), grown on AlN buffered sapphire (0001), shows an x-ray diffraction rocking curve full width at half maximum (FWHM) of 5–7 arc-min. The ion channeling minimum yield in the surface region for AlN and GaN is ∼3%, indicating a high degree of crystallinity. The optical band gap for AlN and GaN is found to be 6.2 and 3.4 eV, respectively. These epitaxial films are shiny, and the surface root mean square roughness is ∼5–15 nm. The electrical resistivity of the GaN films is in the range of 10⁻²–10² Θ-cm with a mobility in excess of 80 cm²V⁻¹s⁻¹ and a carrier concentration of 10¹⁷–10¹⁹ cm⁻³, depending upon the buffer layers and growth conditions. We have also demonstrated the application of the pulsed laser deposition technique for integration of technologically important materials with the III–V nitrides. The examples include pulsed laser deposition of ZnO/GaN heterostructures for UV-blue lasers and epitaxial growth of TiN on GaN and SiC for low resistance ohmic contact metallization. Employing the pulsed laser, we also demonstrate a dry etching process for GaN and AlN films.     

溅射功率对AlN薄膜结构形貌的影响

采用直流反应磁控溅射法在Si(111)基片上制备了AlN薄膜,利用X线衍射(XRD)、场发射扫描电子显微镜(FESEM)、原子力显微镜(AFM)对不同溅射功率下制备的AlN薄膜的结构及形貌进行了分析表征。结果表明:在一定范围内,随着溅射功率的增大,薄膜厚度增加,晶粒逐渐长大,表面粗糙度也随之增大;AlN(002)择优取向改善明显,120W时达到最佳。     

High Performance PbS Colloidal Quantum Dot Solar Cells by Employing Solution‐Processed CdS Thin Films from a Single‐Source Precursor as the Electron Transport Layer

CdS thin films are a promising electron transport layer in PbS colloidal quantum dot (CQD) photovoltaic devices. Some traditional deposition techniques, such as chemical bath deposition and RF (radio frequency) magnetron sputtering, have been employed to fabricate CdS films and CdS/PbS CQD heterojunction photovoltaic devices. However, their power conversion efficiencies (PCEs) are moderate compared with ZnO/PbS and TiO₂/PbS heterojunction CQD solar cells. Here, efficiencies have been improved substantially by employing solution‐processed CdS thin films from a single‐source precursor. The CdS film is deposited by a straightforward spin‐coating and annealing process, which is a simple, low‐cost, and high‐material‐usage fabrication process compared to chemical bath deposition and RF magnetron sputtering. The best CdS/PbS CQD heterojunction solar cell is fabricated using an optimized deposition and air‐annealing process achieved over 8% PCE, demonstrating the great potential of CdS thin films fabricated by the single‐source precursor for PbS CQDs solar cells.     

直流磁控溅射制备非晶硅薄膜的研究

非晶硅薄膜（a-Si）是目前重要的光敏材料,在很多领域得到广泛应用。直流磁控溅射具有工艺简单．沉积温度低等优点,是制备薄膜的一种重要技术。采用直流磁控溅射工艺在玻璃基板上沉积薄膜,并对样品进行了退火处理。研究了沉积速率与溅射功率的关系。结果表明薄膜的沉积速率与溅射功率近似有线性关系。利用X射线衍射（XRD）对薄膜进行了分析鉴定,结果表明溅射的薄膜是非晶硅薄膜。利用扫描电子显微镜（SEM）对非晶硅薄膜的表面形貌进行了观察和分析,与X射线衍射测试的结果一致。所以．利用直流磁控溅射工艺能在常温下能快速制备出良好的非晶硅薄膜。     

金刚石基底上制备(002)AlN薄膜的研究

首先采用微波等离子体化学气相沉积(MPCVD)方法,在O2/H2/CH4混合气体气氛下利用大功率微波在(100)Si片上生长出了异质外延金刚石膜,X-射线衍射(XRD)、拉曼光谱和场发射扫描电子显微镜(FESEM)对薄膜的表征分析结果表明,制备的金刚石膜具有很高的金刚石相纯度,且晶粒排列紧密;继而采用射频磁控反应溅射法,在抛光的金刚石基底上成功制备了高C轴择优取向的氮化铝(AlN)薄膜,研究了不同的溅射气压、靶基距对AlN薄膜制备的影响,XRD检测结果表明,溅射气压低,靶基距短,有利于AlN(002)面择优取向,相反则更有利于AlN薄膜的(103)面和(102)面择优取向;研究了AlN薄膜在以N终止的金刚石基底和纯净金刚石基底两种表面状态上的生长机制,结果发现,以N终止的金刚石基底非常有利于AlN(002)面择优取向生长;从Al-N化学键的形成以及溅射粒子平均自由程的角度,探讨了其对AlN薄膜择优取向的影响。