PECVD法制备非晶硅薄膜及光电性能研究

采用等离子体增强化学气相沉积（PECVD）方法在玻璃衬底上制备出非晶硅薄膜,利用正交试验法对射频功率、气体总压、硅烷比例、沉积时间、退火温度、退火时间因素进行了研究,对透过率和电阻率进行了分析,结果表明,采用PECVD法成功制备出非晶硅薄膜。正交实验表的分析得知,气体总压对透过率影响最大;硅烷比例对电阻率影响最大。制备非晶硅薄膜的优化条件为：射频功率30W、气体总压100Pa,硅烷5％、沉积时间5min、退火温度300℃、退火时间45min。非晶硅薄膜的光透过率93．18％,电阻率为13．238kΩ·cm。     

掺硼纳米非晶硅的太阳能电池窗口层应用研究

本文通过等离子体增强化学气相沉积(PECVD)法沉积p型纳米非晶硅薄膜(na-si:H),系统地研究了掺杂气体比(B2H6/SIH4)、沉积温度、射频电源功率对薄膜结构、光学、电学性能的影响.研究表明,轻掺硼有利于非晶硅薄膜晶化,但随着掺硼量的增加,硼的"毒化"作用又使薄膜变为非晶态;与p型a_si:H相比,掺硼纳米硅薄膜的光学带隙Eopt较高,电导率较高,电导激活能较低,是一种很有潜力的太阳能电池窗口层材料.     

ICPCVD低温生长非晶硅的工艺及光学特性研究北大核心CSCD

文章利用ICPCVD在100℃及以下玻璃和蓝宝石片衬底上生长非晶硅薄膜,并通过调节Ar和SiH4气体流量比例、射频功率及衬底温度等参数,实现低温下高质量非晶硅薄膜的生长。随后用拉曼光谱表征分析研究了衬底温度变化对非晶硅薄膜沉积质量的影响,并计算出衬底温度为100℃时,非晶硅薄膜的结晶分数和微晶尺寸分别为64.4%和4.7 nm。此外还研究了非晶硅薄膜折射率和透过率等光学特性,并计算出薄膜的光学带隙最低为1.68。最后制备了两种a-Si/SiO_(2)/a-Si布拉格反射结构,厚度分别为36/100/41 nm和62/132/60 nm。两种结构在可见光和红外波段分别实现了90.4%和88.9%的最高反射率。     

氢化非晶硅薄膜光衰退稳定性的影响因素

用热丝辅助微波电子回旋共振化学气相沉积制备样品,通过红外吸收谱图和光衰退图,分析影响a-SiH薄膜光衰退稳定性的因素一方面,非晶硅网格中氢含量、氢硅键合方式以及氢的运动情况均对非晶硅材料的稳定性起着十分重要的作用,另一方面,在非晶硅的基体上生长少量微晶硅,可提高薄膜的稳定性.最终希望能通过两者的结合来探讨如何制备高光敏性和低光致衰退的非晶硅薄膜.     

PECVD法沉积氢化非晶硅薄膜内应力的研究

利用等离子体增强化学气相沉积技术在硅基底上沉积了氢化非晶硅(α-Si:H)薄膜,通过纳米压入仪、电子薄膜应力分布仪、傅里叶变换红外光谱仪等表征技术,研究了沉积时的工艺参数(射频功率、沉积温度、工作压强)对薄膜内应力的影响,对薄膜的本征应力、热应力进行分析,并探讨了射频功率对薄膜红外吸收光谱的影响。研究结果表明,提高射频功率能够使薄膜从张应力转变为压应力,且压应力随射频功率的增大而增大;提高工作压强能够使薄膜从压应力转变为张应力;应力随沉积温度的升高而增大;薄膜中氢含量、SiH组态、SiH2组态含量随射频功率的增大而增大。通过优化工艺,得到了沉积具有较小张应力薄膜的工艺参数(射频功率30W,沉积温度250℃,气体流量80cm3/min(标准状态),工作压强67Pa),并将其成功应用于非晶硅薄膜自支撑悬空结构。     

非晶硅薄膜的沉积速率研究

利用PECVD方法在硅片上制备了非晶硅薄膜,通过正交实验得出影响薄膜沉积速率和折射率的主要参数为气体流量和射频功率,分别研究了这两个参数对沉积速率和折射率的影响.结果表明当气体流量低于240sccm时,薄膜沉积速率随气体流量增加而增加,而折射率则随之减小;当流量大于240sccm时,沉积速率出现饱和,折射率的变化并不明显.当射频功率低于120W时,薄膜沉积速率随着功率的提高而增大,而折射率则随之减小;当功率大于120W并进一步提高时,沉积速率成下降趋势,折射率则随之增大.     

我国第五代大面积非晶硅薄膜电池率先实现量产

据报道,国内薄膜太阳能电池领军企业强生光电近日在沪宣布,第五代大面积非晶硅薄膜电池率先在该公司投入批量生产。据介绍,非晶硅薄膜电池因其沉积均匀度要求高,面积越大,成本越低,但设备及工艺要求也越高。国际上能够制造第五代薄膜电池     

PECVD法制备纳米晶粒多晶硅薄膜

采用射频等离子体增强化学气相沉积系统(RF-PECVD)以高纯SiH4为气源在P型<100>晶向单晶硅片上、衬底温度600℃、射频(13.56MHz)电源功率50W时沉积非晶硅薄膜,利用高温真空退火制作纳米晶粒多晶硅薄膜.采用x射线衍射仪(XRD)、Raman光谱、AFM测量和分析薄膜微结构及表面形貌,实验结果表明,退火温度为800℃时非晶硅薄膜晶化,形成择优取向为<111>晶向的多晶硅薄膜;退火温度增加,Raman谱TO模和TA模强度逐渐减弱;AFM给出800℃退火后薄膜晶粒明显细化,形成由20～40nm大小晶粒组成的多晶硅薄膜,薄膜晶粒起伏程度明显减弱.     

用于HIT太阳能电池的本征非晶硅薄膜

带本征薄层的异质结（HIT）太阳能电池要求本征非晶硅薄膜具有生长速率低，暗电导大，光学带隙宽的特点。采用等离子增强化学气相沉积（PECVD）制备符合HIT太阳能电池要求的本征非晶硅薄膜，并通过分析薄膜的透射光谱，采用Tauc法计算了薄膜的光学带隙，为约1．87eV，衬底温度为180℃，放电功率为80W时获得的薄膜性能最佳。     

等离子体增强化学气相沉积设备的研制

本文介绍非晶硅薄膜太阳能电池生产线的核心设备——等离子体增强化学气相沉积(PECVD, Plasma Enhanced Chemical Vapor Deposition)系统,并阐述了其重要地位.非晶硅太阳能电池制造的关键技术是非晶硅薄膜的制备,目前最常见的制备方法是PECVD技术.PECVD技术凭借其低温沉积、可大面积成膜、成膜均匀等特点,在非晶硅薄膜制备方面迅速发展.PECVD系统用于制备非晶硅太阳能电池的关键结构P、I、N硅薄膜层.本文阐述了该设备的结构特点、技术指标、工作原理及工艺过程,对沉积室的结构和配置进行了详细设计计算,非晶硅太阳能电池稳定后的转化效率可达6％.     

白宝石上生长SiO2薄膜的工艺

用射频磁控反应溅射法,以高纯Si为靶材,高纯O2为反应气体,在白宝石上制备SiO2薄膜。对影响薄膜生长的工艺参数进行了分析,测试了薄膜的成分,并研究了薄膜的红外光学性能。结果表明,制备的薄膜中Si和O形成SiO2化学键,计算出的O与Si的原子比接近2:1,采用射频磁控反应溅射法在白宝石上能够沉积出SiO2薄膜。制备出的SiO2薄膜对白宝石衬底有较好的增透作用。     

Structural and optical properties of yttrium trioxide thin films prepared by RF magnetron sputtering

Yttrium trioxide (Y₂O₃) thin films have been deposited on silicon (111) at different RF powers and the sputtering pressures by RF magnetron sputtering. The influences of the RF power and the sputtering pressures on the structural and optical properties of Y₂O₃ thin films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM) and spectroscopic ellipsometer (SE). The results show that chemical composition of as-deposited Y₂O₃ film is apparently close to the stoichiometric ratio and it is crystallized but crystallinity is poor. The monoclinic and cubic fluorite-like structure can coexist in as-deposited Y₂O₃ film. A four-layer-structured optical model consisting of silicon substrate, silicon dioxide (SiO₂) interlayer, Y₂O₃ layer and a surface roughness (SR) layer is built for interpreting preferably the results measured by spectroscopic ellipsometry. With the increase of RF power or decrease of sputtering pressure, the refractive index and optical bandgap of sputtered Y₂O₃ film is increased and the extinction coefficients is decreased.     

Structural and optical properties of yttrium trioxide thin films prepared by RF magnetron sputtering

Yttrium trioxide (Y₂O₃) thin films have been deposited on silicon (111) at different RF powers and the sputtering pressures by RF magnetron sputtering. The influences of the RF power and the sputtering pressures on the structural and optical properties of Y₂O₃ thin films were investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), atomic force microscope (AFM) and spectroscopic ellipsometer (SE). The results show that chemical composition of as-deposited Y₂O₃ film is apparently close to the stoichiometric ratio and it is crystallized but crystallinity is poor. The monoclinic and cubic fluorite-like structure can coexist in as-deposited Y₂O₃ film. A four-layer-structured optical model consisting of silicon substrate, silicon dioxide (SiO₂) interlayer, Y₂O₃ layer and a surface roughness (SR) layer is built for interpreting preferably the results measured by spectroscopic ellipsometry. With the increase of RF power or decrease of sputtering pressure, the refractive index and optical bandgap of sputtered Y₂O₃ film is increased and the extinction coefficients is decreased.     

Poly-crystalline silicon thin films prepared by plasma-assisted hot-wire chemical vapor deposition

A combination of hot-wire chemical vapor deposition (HWCVD) and RF plasma, referred to as plasma-assisted HWCVD (P-HWCVD) was used to prepare poly-crystalline silicon (poly-Si) thin films. The effects of the plasma on the film properties were studied by varying the RF power (P_w) from 0 to 40 W. The results indicate that, compared with that of HWCVD samples, the film crystalline fraction (X_c) is enhanced at low P_w assistance, whereas it decreases at higher P_w. The uniformity of the film thickness is considerably improved by introducing plasma. It is also found that the porosity of the film, indirectly detected from infrared spectra, is much reduced. Auger analysis of the tantalum filament used in the P-HWCVD process shows much lower silicon contamination than that in HWCVD.     

RF sputtered piezoelectric zinc oxide thin film for transducer applications

This paper demonstrates the substrate dependency of the c-axis zinc oxide growth in radio-frequency sputtering system. Different deposition conditions were designed to study the influences of Si, SiO₂/Si, Au/Ti/Si, and Au/Ti/SiO₂/Si substrates on the piezoelectric and crystalline qualities of the ZnO thin films. Experimental results showed that the multilayer of Au/Ti/SiO₂/Si-coated silicon substrate provided a surface that facilitated the growth of ZnO thin film with the most preferred crystalline orientation. The 1.5 μm-thick thermally grown amorphous silicon dioxide layer effectively masked the crystalline surface of the silicon substrate, thus allowing the depositions of high-quality 20 nm-thick titanium adhesion layer followed by 150 nm-thick of gold thin film. The gold-coated surface allowed deposition of highly columnar ZnO polycrystalline structures. It was also demonstrated that by lowering the deposition rate at the start of sputtering by lowering RF power to less than one-third of the targeted RF power, a fine ZnO seed layer could be created for subsequent higher-rate deposition. This two-step deposition method resulted in substantially enhanced ZnO film quality compared to single-step approach. The influence of stress relaxation by annealing was also investigated and was found to be effective in releasing most of the residual stress in this layered structure.     

Residual stress on nanocrystalline silicon thin films deposited under energetic ion bombardment by using internal ICP-CVD

Nano/microcrystalline silicon thin films were deposited using an internal-type, inductively coupled, plasma-chemical vapor deposition (ICP-CVD) at room temperature by varying the bias power to the substrate. The structural characteristics of the deposited thin film were investigated. The deposition rate was increased by the application of a small RF bias power of 30 W (12.56 MHz), but was then decreased as the bias power was increased above 30 W. In addition, the application of bias power generally increased the residual compressive stress, which was attributed to the increased defect formation in the thin film due to the formation of interstitial atoms. The crystalline volume fraction was also decreased with increasing bias power. However, in the low bias power range of 0-60 W, the compressive stress in the deposited thin film was in the range of − 34 to − 77 MPa, which was lower than the residual stress in the range of − 150 to − 1050 MPa that is observed for the nano/microcrystalline silicon thin films deposited by capacitively coupled plasma.     

Plasmachemische Gasphasenabscheidung – eine Technologie zur Deposition organischer und anorganischer Schichten. Plasma Enhanced Chemical Vapor Deposition – a Thin Film Technique for Organic and Inorganic Layers

Plasma enhanced chemical vapor deposition (PECVD) has a wide range of interest for thin films up to some μm thickness. It has widespread applications for high quality dielectric and semiconducting silicon alloys at deposition temperatures below 450 °C and pressures at 1 mbar on plane substrates and attracts growing attention for the surface modification of polymers. The PECVD takes advantages of the possibility to alter the film properties in a wide range easily, and the coatings can achieve a variety of useful properties unobtainable by other coating techniques. An environmentally friendly plasma chemical reactor etch cleaning of SiO_x, SiN_x and other film materials can be applied by changing the process gas and without breaking the vacuum. PECVD can be used in a fixed substrate and continuous substrate flow mode. An capacitively coupled parallel‐plate electrode assembly using radio‐frequency (RF) excitation of the discharge is most widely used for substrate areas up to a few square meters. Among the capacitively excitation an inductively and electromagnetically excitation at frequencies in the RF and UHF range has also succeeded in achieving a high rate PECVD. Two applications are presented to show the characteristics and the potential of this technique, the PECVD of semiconducting hydrogenated amorphous silicon, intrinsic or doped, with low power densities using monosilane as a source gas for solar cells, thin films transistors and digital image sensors and the plasma polymerisation of organosilicon protection layers employing the HMDSO monomer and high power densities for mirrors and lenses.     

Optical,electrical and mechanical properties of Ga-doped ZnO thin films under different sputtering powers

We present the optical, electrical and mechanical properties of Ga-doped zinc oxide (GZO) thin films prepared by radio-frequency (RF) magnetron sputtering at room temperature under different RF powers (80–180 W). The thickness, electron concentration, and electron mobility of the GZO thin film were determined by fitting the visible-to-near-infrared transmittance spectrum of GZO film/glass using the transfer matrix method. The bending force per unit width was measured by a home-made Twyman–Green interferometer with the fast Fourier transform method. The obtained results show that the optical, electrical and mechanical properties of GZO thin film are subject to the RF power. At an RF power of 140 W, the local minimum of bending force per unit width corresponds to the highest electron mobility in GZO thin film. This study demonstrates that the optical, electrical and mechanical properties of GZO thin film can be fully resolved by non-contact optical methods.     

PECVD法生长氮化硅工艺的研究

采用了等离子体增强化学气相沉积法(plasma-enhanced chemical vapor deposition,PECVD)在聚酰亚胺(polyimide,PI)牺牲层上生长氮化硅薄膜,讨论沉积温度、射频功率、反应气体流量比等工艺参数对氮化硅薄膜的生长速率、氮硅比、残余应力等性能的影响,得到适合制作接触式射频MEMS开关中悬梁的氮化硅薄膜的最佳工艺条件.     

Relation between the plasma characteristics and physical properties of functional zinc oxide thin film prepared by radio frequency magnetron sputtering process

The ZnO thin film was deposited on a glass substrate by a RF reactive magnetron sputtering method. Results showed that plasma density, electron temperature, deposition rate and estimated ion bombardment energy increase with increasing applied RF power. Three distinct power regimes were observed, which are strongly correlated with plasma properties. In the low-power regime, the largest grain size was observed due to slow deposition rate. In the medium-power regime, the smallest grain size was found, which is attributed to insufficient time for the adatoms to migrate on substrate surface. In the high-power regime, relatively larger grain size was found due to very large ion bombardment energy which enhances the thermal migration of adatoms. Regardless of pure ZnO thin film or ZnO on glass, high transmittance (> 80%) in the visible region can be generally observed. However, the film thickness plays a more important role for controlling optical properties, especially in the UV region, than the applied RF power. In general, with properly coated ZnO thin film, we can obtain a glass substrate which is highly transparent in the visible region, is of good anti-UV characteristics, and is highly hydrophobic, which is highly suitable for applications in the glass industry.