脉冲功率对含硅量子点SiCx薄膜物相结构及光谱特性的影响

基于硅量子点（Si-QDs）的全硅叠层太阳电池被认为是最有潜质的高效太阳电池之一。目前所报道的硅量子点薄膜存在硅量子点数密度低、缺陷多等问题,限制了硅量子点太阳电池的光电转换效率。微波退火(microwave annealing, MWA)被认为是一种有益于制备纳米结构材料的方法。微波退火的非热效应可以降低形核能,改善薄膜的微结构和光电性能。因此,采用磁控共溅射技术并结合微波退火工艺,在不同的脉冲功率下制备了含硅量子点SiC_x薄膜;采用掠入射X射线衍射(GIXRD)、拉曼(Raman)光谱、紫外-可见-近红外分光光度计和光致发光(PL)光谱表征薄膜的物相结构及光谱特性;研究不同脉冲功率对硅量子点数密度和性能的影响,进而改进磁控共溅射工艺,制备硅量子点数密度较高和性能良好的薄膜。样品的GIXRD谱和Raman谱均显示其中存在硅量子点,其强度先增大后减小;通过谢乐(Scherrer)公式估算出硅量子点尺寸呈现先增大后减小的规律,脉冲功率为80 W时尺寸达到最大(8.0 nm）。在Raman光谱中还观察到中心位于511 cm-1处出现硅量子点Si-Si横向光学振动模式的拉曼峰,其强度也呈现先增大后减小的趋势;对拉曼光谱做最佳高斯(Gauss)分峰拟合,得出薄膜的晶化率均高于62.58%,脉冲功率为80 W时制备的薄膜具有最高的晶化率(79.29%)。上述分析表明薄膜中均有硅量子点的形成,且数量先增加后减小,脉冲功率为80 W时硅量子点数量最多。通过测量样品的透射率T、反射率R等光学参数,利用Tauc公式估算出薄膜的光学带隙,发现带隙值随溅射功率的增加先减小后增大,在脉冲功率为80 W时最小(1.72 eV)。硅量子点尺寸与光学带隙成反比,说明薄膜中的硅量子点具有良好的量子尺寸效应。通过PL光谱分析样品的发光特性,对其做最佳高斯拟合,发现样品中均有6个发光峰。结合Raman光谱的分析结果,可以得出波长位于463~624 nm的发光峰源于硅量子点的作用;而波长位于408和430 nm的发光峰则源于薄膜内部的缺陷态,峰位没有偏移,但强度有变化。根据发光峰对应的波长可计算其能带分布,从而确定缺陷态类型：408 nm的发光峰归因于≡Si°→E_v电子辐射跃迁,430 nm的发光峰则归因于≡Si°→≡Si-Si≡的缺陷态发光。还研究了硅量子点的尺寸对发光峰移动的影响。结果表明,随硅量子点尺寸变小（大）,发光峰蓝移（红移）。综上,溅射功率为80 W时制备的含硅量子点SiC_x薄膜性能最佳。研究结果为硅量子点太阳电池的后续研究奠定了基础。     

退火工艺对含硅量子点SiC_x薄膜光谱特性的影响

采用磁控共溅射法并结合微波退火和快速光热退火工艺,在不同退火温度下制备了含硅量子点的富硅SiC_x薄膜。采用掠入射X射线衍射(GIXRD)、拉曼光谱和光致发光(PL)光谱技术对薄膜进行了表征,研究了退火工艺对薄膜中硅量子点数量、尺寸、晶化率以及发光峰的影响。结果表明:与快速光热退火相比,微波退火不但能降低硅量子点的形成温度(降低200℃),而且还能降低β-SiC量子点的形成温度(降低100℃);在相同退火温度下,微波退火制备的硅量子点的数量更多、晶化率更高、光致发光峰更强;采用1000℃温度的微波退火样品的硅量子点数量最多、尺寸最大(5.26nm)、晶化率最高(74.25%)、发光峰最强,说明微波退火能凝析出高质量的硅量子点。     

室温射频磁控溅射制备纳米晶ZnSX薄膜及其性能研究

为获得性能优异的透明介质薄膜,采用射频磁控溅射技术,以ZnS陶瓷靶为靶材,在玻璃衬底上室温沉积纳米晶富锌ZnS薄膜,通过X射线衍射仪、场发射扫描电子显微镜、拉曼光谱仪、分光光度计、光谱椭偏仪重点研究了不同射频功率对制备的纳米晶ZnS_X薄膜的晶相结构、表面形貌及光学性能的影响。结果表明:射频功率对ZnS_X薄膜晶相形成和结晶度具有重要影响;随着溅射功率的增加,ZnS_X薄膜中Zn和S元素的比例、特征拉曼峰的强度以及折射率的值都先增大后减小,薄膜的光学带隙从3.86 eV降低至3.76 eV;当溅射功率为150 W时,为ZnS_X薄膜具有立方相结构及高结晶度的最优条件,薄膜的Zn/S比接近于标准化学计量比,达到1.23,可见光平均透过率大于80%,550 nm下ZnS_X薄膜的光学折射率为2.03。     

沉积参数对碳氮化硅薄膜化学结构及光学性能的影响

利用微波电子回旋共振（MW ECR）等离子体增强非平衡磁控溅射法制备了碳氮化硅（SiCN）薄膜。研究结果表明：硅靶溅射功率和氮气流量对薄膜化学结构、光学、力学等性能有很大影响。傅里叶变换红外光谱（FT IR）和X射线光电子能谱（XPS）表征显示，随着硅靶溅射功率由150W增加到350W，薄膜中C Si N键含量由14.3%增加到43.6％; 氮气流量的增大（2～15sccm）易于形成更多的sp2C＝N键和sp1C≡N键。在改变硅靶溅射功率和氮气流量的条件下，薄膜光学带隙最大值分别达到2.1eV和2.8eV。     

室温制备低电阻率高透过率H,W共掺杂ZnO薄膜

采用脉冲直流磁控溅射法,以WO3:ZnO陶瓷靶为溅射靶材,通过在溅射气氛中引入H2的方式,在室温条件下制备了低电阻率、高可见和近红外光区透过率的H,W共掺杂ZnO (HWZO)薄膜.系统地研究了H2流量对所制备的HWZO薄膜的结构、组分、元素价态、光电特性的影响.结果表明:掺入的H可促进Zn的氧化,改善薄膜的结晶质量,提高薄膜透过率.H引入之后薄膜的载流子浓度增加,电阻率降低.在H2流量为6mL/min时制备的HWZO薄膜性能最优,电阻率为7.71×10-4 Ω·m,光学带隙为3.58 eV,400-1100 nm的平均透过率为82.4％.     

溅射工艺参数对硅薄膜微结构影响的Raman分析

为了解决碳化硅难以进行光学加工的问题,该文采用射频磁控溅射方法,在碳化硅反射镜坯体上沉积与碳化硅具有相近热膨胀系数且易于进行光学加工的硅薄膜。利用拉曼光谱(Raman)对衬底温度、射频功率、衬底偏压等溅射工艺条件对硅膜微结构的影响进行了分析。研究发现：随着衬底温度的升高,薄膜的晶化率先增大后减小;衬底偏压的增加不利于薄膜有序结构的形成;射频功率对薄膜微结构的影响比较复杂,随着功率的升高,薄膜晶粒尺寸减小,晶化率降低,当射频功率进一步升高时,薄膜中有序团簇尺寸和晶化率逐渐升高。但过高的射频功率反而不利于薄膜的晶化。     

磁控共溅射低温制备多晶硅薄膜及其特性研究

多晶硅在光电子器件领域具有较为重要的用途。利用磁控溅射镀膜系统,通过共溅射技术在玻璃衬底上制备了非晶硅铝(α-Si/Al)复合膜,将Al原子团包覆在α-Si基质中,膜中的Al含量可通过Al和Si的溅射功率比来调节。复合膜于N₂气氛中进行350 ℃,10 min快速退火处理,制备出了多晶硅薄膜。利用X射线衍射仪、拉曼光谱仪和紫外-可见光-近红外分光光度计对多晶硅薄膜的性能进行表征,研究了Al含量对多晶硅薄膜性能的影响。结果表明：共溅射法制备的α-Si/Al复合膜在低温光热退火下晶化为晶粒分布均匀的多晶硅薄膜;随着膜中Al含量逐渐增加,多晶硅薄膜的晶化率、晶粒尺寸逐渐增加,带隙则逐渐降低;Al/Si溅射功率比为0.1时可获得纳米晶硅薄膜,Al/Si溅射功率比为0.3时得到晶化率较高的多晶硅薄膜,通过Al含量的调节可实现多晶硅薄膜的晶化率、晶粒尺寸及带隙的可控。     

富硅氮化硅薄膜的制备及其光学带隙研究

采用双极脉冲磁控反应溅射法在不同参数条件下制备了一系列氮化硅薄膜。利用数字式显微镜和紫外-可见光光谱仪研究了沉积薄膜的表面形貌及其光学带隙,利用共焦显微拉曼光谱仪比较了硅衬底、氮化硅薄膜退火前后的拉曼光谱。结果表明,氮气流量对薄膜的光学带隙影响较大,制备的薄膜主要为富硅氮化硅薄膜。原沉积薄膜的拉曼光谱存在明显的非晶硅和单晶硅峰,退火处理后非晶硅峰减弱或消失,表明薄膜出现明显的结晶化;单晶硅峰出现频移现象,表明薄膜中出现硅纳米颗粒,平均尺寸约为6.6 nm。     

磁控共溅射法沉积的硅量子点SiN_x薄膜的光谱特性

采用双极脉冲和射频磁控共溅射沉积法在不同温度的Si(100)衬底和石英衬底上制备了富硅SiNx薄膜。在氮气氛中,于1 050℃下采用快速光热退火热处理,获得了包含硅量子点的SiNx薄膜。采用Fourier变换红外光谱、Raman光谱、掠入射X射线衍射和光致发光光谱对退火后的薄膜样品进行了表征。结果显示:Fourier变换红外光谱中出现了富硅Si—N键,表明薄膜为富硅SiNx薄膜;当衬底温度不低于200℃时,薄膜样品的拉曼光谱中出现了硅纳米晶的Si—Si振动横光学模,掠入射X射线衍射中出现了明显的Si(111)和Si(311)的衍射峰,证实了硅量子点的形成;发现存在一最佳衬底温度(300℃),该条件下获得的硅量子点的数量和晶化率最高;衬底温度为300和400℃的样品的光致发光光谱中均有3个可见荧光峰,结合拉曼光谱结果,用纳米晶硅的量子限域效应和辐射复合缺陷态对荧光峰进行了合理解释;由光致发光光谱计算出的衬底温度为300和400℃的样品的硅量子点平均尺寸分别为3.5和3.4nm。这些结果有助于优化含硅量子点的SiNx薄膜的制备参数,在硅基光电子器件的应用方面有重要意义。     

氧化硅层厚度对Si/SiO2界面电子态结构与光学性质的影响

在氧化硅上生长纳米硅晶,保持氧化硅的直接带隙结构,降低其能带带隙,以用于发光和光伏。采用基于密度泛函理论的第一性原理研究了块体α-方石英、薄膜α-方石英、Si/SiO₂界面的电子态结构和Si/SiO₂界面的光学性质。结果显示,其均为直接带隙半导体,当薄膜α-方石英厚度和Si/SiO₂界面氧化硅层厚度逐渐减小时,能带带隙均逐渐变大,表现出明显的量子限制效应。光学性质计算结果表明：Si/SiO₂界面虚部介电峰和吸收峰的峰值随氧化硅层厚度降低而显著升高,且峰位向高能量方向蓝移。使用脉冲激光沉积制备了氧化硅上硅晶薄膜,测量了Si/SiO₂界面样品的PL光谱,在670 nm处存在一个强的发光峰,在波长超过830 nm后,Si/SiO₂界面样品的发光强度不断升高。因此,可以通过控制Si/SiO₂界面氧化硅层厚度有效地调控Si/SiO₂界面的电子态结构和光学性质,引进边缘电子态,调控其带隙进入1～2 eV区间,获取硅基发光材料...     

Influence of target substrate distance on the properties of transparent conductive Si doped ZnO thin films

Si doped zinc oxide (SZO, Si3%) thin films are grown at room temperature on glass substrates under argon atmosphere, using direct current magnetron sputtering. The influence of the target substrate distances on structure, morphology, optical and electrical properties of SZO thin films is investigated. Experimental results show that the target substrate distances have a significance impact on the growth rate, crystal quality and electrical properties of the films, and have little impact on the optical properties of the films. SZO thin film samples grown on glasses are polycrystalline with a hexagonal wurtzite structure and have a preferred orientation along the c-axis perpendicular to the substrate. When the target substrate distance decreases from 76 to 60 mm, the degree of crystallization of the films increased, the grain size increases, and the resistivity of films decreases. However, when the distance continuously decreases from 60 to 44 mm, the degree of crystallization of the films decreased, the grain size decreases, and the resistivity of the films increases. SZO(3%) thin films deposited at a target substrate distance of 60 mm show the lowest resistivity of 5.53 × 10⁻⁴ Ω cm, a high average transmission of 94.47% in the visible range, and maximum band gap of 3.45 eV under 5 Pa of argon at sputtering power of 75 W for sputtering time of 20 min.     

低温铝诱导晶化制备纳米晶硅薄膜的物相和光学性能研究

采用射频磁控溅射镀膜系统,在玻璃衬底上制备了非晶硅(α-Si)/铝(Al)复合薄膜,结合氮气(N₂)气氛中低温快速光热退火制备了纳米晶硅(nc-Si)薄膜;利用光学显微镜、共焦光学显微仪、X射线衍射(XRD)仪、拉曼散射光谱(Raman)仪和紫外-可见光-近红外分光光度计(UV-VIS-NIR)对纳米晶硅薄膜的表面形貌、物相及光学性能进行了表征,研究了退火工艺对薄膜性能的影响。结果表明： 300 ℃,25 min光热退火可使α-Si/Al膜晶化为纳米晶硅薄膜,晶化率为15.56%,晶粒尺寸为1.75 nm;退火温度从300 ℃逐渐升高到400 ℃,纳米晶硅薄膜晶粒尺寸、晶化率、带隙逐渐增加,表面均匀性、晶格畸变量逐渐减小;退火温度从400 ℃逐渐升高到500 ℃,纳米晶硅薄膜的晶粒尺寸、晶化率继续增加,带隙则逐渐降低;采用纳米晶硅薄膜的吸光模型验证了所制备的纳米晶硅薄膜的光学特性,其光学带隙的变化趋势与吸光模型得出的结果一致。     

Effect of RF power and sputtering pressure on the structural and optical properties of TiO2 thin films prepared by RF magnetron sputtering

TiO₂ thin films were deposited onto quartz substrates by RF magnetron sputtering. The samples deposited at various RF powers and sputtering pressures and post annealed at 873 K, were characterized using X-ray diffraction (XRD), micro Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence (PL) spectroscopy. XRD spectrum indicates that the films are amorphous-like in nature. But micro-Raman analysis shows the presence of anatase phase in all the samples. At low sputtering pressure, increase in RF power favors the formation of rutile phase. Presence of oxygen defects, which can contribute to PL emission is evident in the XPS studies. Surface morphology is much affected by changes in sputtering pressure which is evident in the SEM images. A decrease in optical band gap from 3.65 to 3.58 eV is observed with increase in RF power whereas increase in sputtering pressure results in an increase in optical band gap from 3.58 to 3.75 eV. The blue shift of absorption edge in all the samples compared to that of solid anatase is attributed to quantum size effect. The very low value of extinction coefficient in the range 0.0544-0.1049 indicates the excellent optical quality of the samples. PL spectra of the films showed emissions in the UV and visible regions.     

氧化硅稳定的氧化锡量子点薄膜的制备及其光学性能

 用溶胶-凝胶-水热过程制备了氧化硅稳定的氧化锡量子点,然后将其分散到氧化硅溶液中,用旋转涂膜的方法制备光学性能良好的氧化硅稳定的氧化锡量子点薄膜。X射线衍射和高分辨透射电镜表征显示氧化锡量子点具有良好的四方金红石晶型,平均粒径约4.0 nm。室温光致发光显示这种氧化硅稳定的氧化锡量子点薄膜在356 nm和388 nm处分别有很强的激子发光和缺陷态发光。根据透射谱拟合得到了氧化锡量子点薄膜的光学禁带宽度,其值约为3.96 eＶ。     

氮分压对氮化铜薄膜结构及光学带隙的影响

在不同的氮分压r(r=N₂/［N₂+Ar］)和射频功率P下，使用反应射频磁控溅射法，在玻璃基片上制备了氮化铜薄膜样品.用台阶仪测得了薄膜的厚度，用原子力显微镜、X射线衍射仪、紫外-可见光谱仪对薄膜的表面形貌、结构及光学性质进行了表征分析.结果表明，薄膜的沉积速率随P和r的增加而增大.薄膜表面致密均匀，晶粒尺寸为30nm左右.随着r的增加，薄膜颗粒增大，且薄膜由(111)晶面转向(100)晶面择优生长.薄膜的光学带隙E_g在1.47—1.82eV之间，随r的增加而增大. 关键词： 氮化铜薄膜 反应射频磁控溅射 晶体结构 光学带隙     

Optical and mechanical properties of AlF3 films produced by pulse magnetron sputtering of Al targets with CF4/O2 gas

In this study, AlF₃ thin films were deposited by pulse magnetron sputtering of Al targets with different ratios of CF₄/O₂ gas and at different sputtering powers. The optical and mechanical properties of the AlF₃ thin films were analyzed. The transmittance spectra showed no obvious negative inhomogeneous refractive indices. Denser films with a low optical absorption were obtained when high sputtering powers were used (larger than 30 W). The lowest extinction coefficient (7.3 × 10⁻⁴ at 193 nm) of the films can be reached with 12 sccm O₂ flow rate and at 160W sputtering power. All of the residual stresses were compressive and their trends were consistent with the refractive indices. The lowest compressive stress (0.068 GPa) was obtained when the AlF₃ films were prepared at 160W sputtering power.     

Effect of balanced and unbalanced magnetron sputtering processes on the properties of SnO2 thin films

A comparative study has been carried on the role of balanced magnetron (BM) and unbalanced magnetron (UBM) sputtering processes on the properties of SnO₂ thin films. The oxygen partial pressure, substrate temperature and deposition pressure were kept 20%, 700 °C and 30 mTorr, respectively and the applied RF power varied in the range of 150–250 W. It is observed that the UBM deposition causes significant effect on the structural, electrical and optical properties of SnO₂ thin films than BM as evidenced by X-ray diffraction, C-V, Spectroscopic Ellipsometer and Photoluminescence measurements. The value of band gap (E_g) of the films deposited at 150 W in UBM is found as E_g = 3.83 eV which is much higher than the value of E_g = 3.69 eV as observed in BM sputtering indicating that UBM sputtering results in good crystalline quality. Further, the C-V measurements of SnO₂ thin films deposited using UBM at high power 250 W show hysteresis with large flat band shift indicating that these thin films can be used for the fabrication of memory device. The observed results have been attributed to different mechanisms which exist simultaneously under unbalanced magnetron sputtering due to ion bombardment of growing SnO₂ thin film by energetic Ar+ ions.