M-PECVD制备高阻隔薄膜研究

在传统的等离子体增强化学气相沉积(plasma-enhanced chemical vapor deposition)技术基础上,通过添加磁场来约束等离子体相中的电子,增加单体有机大分子的电离率,称为磁化等离子体(M-PECVD)技术。实验采用六甲基二硅氧烷和氧气混合气体作为沉积氧化硅薄膜的前驱气体,在厚度为12μm的PET薄膜表面沉积氧化硅薄膜。通过FTIR分析薄膜的结构成分,表明不同的功率对沉积薄膜的结构没有影响,只是对应于1030cm-1的Si—O峰的强度不一样.氧气透过率(OTR)测量发现:随着功率升高,薄膜的OTR先降低,在功率为190W时为最小值(OTR=0.732mL/m2/day);然后随着功率的增大,扫描电镜(Scanning electronic microscopy)OTR上升至2.0mL/m2/day,并保持不变。为了进一步研究薄膜的表面形貌和阻隔性能的关系,通过SEM进行表面相貌分析,发现沉积薄膜表面为有序的棒状结构,并通过薄膜的截面图推算出薄膜沉积速率为4.0nm/s。     

射频磁控溅射SiOx薄膜的制备与阻隔性能研究

利用磁控溅射技术,以SiO2为靶材,Ar为射频源气体,在PET基材上制备SiOx薄膜.研究了不同放电功率、氩气流量、镀膜时间等参数对SiOx薄膜阻隔性能的影响.结果表明:在一定范围内,薄膜的阻隔性能随放电功率的增大而增大,而后逐渐减小;氩气流量对薄膜的阻隔性能也有一定影响;镀膜时间在10min时SiOx薄膜的阻隔性能最好.扫描电镜SEM测试表明,在氩气流量为100cm3/min,镀膜时间10min,1500W放电功率下制备的SiOx薄膜阻隔性能较好、表面较均匀.     

LaB6薄膜的制备工艺研究

分别用电子束蒸发和电泳的方法在不同的衬底上制备出了LaB6薄膜,用扫描电镜（SEM）对样品表面形貌进行了分析,同时利用x射线衍射（XRD）分析了成膜参数衬底温度以及退火处理对LaB6薄膜结晶性能的影响。结果表明,所得样品为LaB6多晶薄膜,合适的衬底温度和退火处理能够提高LaB6薄膜的结晶质量。并对两种成膜方式进行了比较。     

负热膨胀ZrW2O8薄膜的制备和性能

用交替射频磁控溅射法在石英基片上沉积并退火制备了ZrW2O8薄膜,测量了薄膜与基片之间的结合力和薄膜厚度,研究了薄膜的负热膨胀特性.结果表明:用磁控溅射方法制备的薄膜为非晶态,表面平滑、呈颗粒状,在1200℃热处理3 min后得到立方相ZrW2O8薄膜,结晶薄膜的颗粒长大,薄膜与基片之间有良好的结合力.立方相ZrW2O8薄膜在15-200℃热膨胀系数为-24.81×10-6K-1,200-700℃热膨胀系数为-4.78×10-6K-1,平均热膨胀系数为-10.08×10-6K-1.     

Optical properties and structure of thin SiOx films

The optical properties of SiO_x films of variable composition obtained by reactive r.f. sputtering of silicon were investigated.The experimental results show that the films have a single-phase structure consisting of a continuous random network with a dominance of six-membered molecular rings of Si-(Si_yO_4-y tetrahedra, where 0⩽y⩽4, joined together by bridging oxygen atoms. The difference between the films investigated and those obtained by vacuum evaporation is determined by the dominance of four-membered rings in the evaporated films.Analysis of the IR spectra reveals that the shift in the absorption band with varying structure is connected with a variation in the central force constant.     

Electroforming in MIM structure of SiOx and SiOx/SnO composite dielectric thin films

Electroforming and related phenomena in SiO _x and SiO _x -SnO thin films incorporated in copper-oxide-copper metal-insulator-metal structures have been investigated. Both types of devices showed voltage-controlled negative resistance, voltage memory effects (thermal and threshold) and electron emission. The voltage-controlled negative resistance and voltage memory effects may be interpreted in terms of the filamentary model of Dearnaley et al. The electron emission phenomenon is attributed to the Dearnaley model as modified by Rakhshani et al. The a.c. conductance of the devices before and after forming was also studied and the results support the proposed filamentary model of the electroforming process.     

铝掺杂对非晶SiOx薄膜电致发光的影响

为提高硅基薄膜（SiOx）发光材料的发光效率，采用双离子束溅射法制备了不同铝含量的Al—Si—SiOx薄膜。对所制备样品的电致发光（EL）测试表明：由于金属（Al）的掺入，使得在同样的电压下。薄膜中的电流随着铝含量的增加而增加；并且铝含量增大使得通过薄膜的电流增强，因而得到较高强度的电致发光。所以当硅基薄膜中掺入铝时，薄膜的发光效率得以提高；并且，随着铝含量的增加，薄膜的发光效率亦相应提高。     

SiOx薄膜的制备及发光特性研究

本论文采用双离子束溅射沉积技术制备了非晶的SiOx薄膜，XPS的测试表明Si是以单原子或低价氧化物的形态存在于薄膜内；在波长为240nm紫外光的激发下，室温及1000℃退火后SiOx薄膜的PL谱图显示样品中存在峰位分别处于320nm，410nm，560nm，630nm四个相互分离的峰，其发光机制分别为来自中性氧空位缺陷（≡Si—O—O—Si≡）、双配位硅悬挂键（O-Si-O）、非桥氧空位中心以及其他缺陷所形成的发光中心。     

Optical and dielectric properties of thin SiOx films of variable composition

The effect of the composition of amorphous SiO_x films produced by the vacuum evaporation of SiO, on their optical and dielectric properties was investigated. The variation in the composition of the films was achieved by changing the deposition rate and the pressure of the residual gases.The optical band gap was observed to increase from 2.2 to 3.1 eV as the deposition rate was decreased from 50 to 5 Å s^-1 and simultaneously the refractive index, the permittiviity and the dielectric loss factor were found to decrease. The composition and structure of the films were determined from the optical absorption and IR spectroscopy.The experimental results revealed that SiO_x films produced by vacuum evaporation do not comprise a simple mixture of silicon and SiO₂ phases but they have a single-phase structure.     

Effects of thickness and deposition rate on the optical absorption properties of co-evaporated Mn/SiOx, Cr/SiOx and Cu/SiOx thin films

Abstracts are not published in this journal     

Lasing action in organic semiconductor thin films

Lasing action in optically pumped thin films of organic semiconductors has recently been demonstrated in a variety of materials employing a variety of cavity configurations. The excitation intensities required for lasing in optically pumped films are comparable to the electrical current densities achievable in light emitting devices based on these materials, opening the door to the possible realization of organic diode lasers. However, the design of diode laser structures is complicated by the relatively low charge carrier mobilities of organics. It has also been shown that the optical properties of organic films under electrical excitation are affected by the formation of polarons, imposing yet another obstacle for realization of these devices. The continuing research on organic diode lasers is motivated by the unique properties of these devices, such as narrow spectral emission linewidth and the temperature independence of laser output power and emission wavelength, which may be advantageous in a number of applications.     

Fabrication of thin crystal films of organic compounds

A technique for thin film preparation from non-polar organic molecules based on the Langmuir technique is suggested. By removing the organic crystallites of organic molecules from the water surface to the substrate, high-quality textures were obtained with a simultaneous check of their thicknesses. The films produced were analysed by the transmission high-energy electron diffraction technique.     

Micron-sized fracture experiments on amorphous SiOx films and SiOx/SiNx multi-layers

In this study miniaturized monolithic cantilevers of thermally grown silicon oxide and multi-layer cantilevers of plasma enhanced chemical vapor deposited silicon oxide and nitride were mechanically characterized. In order to determine the fracture stress as well as the fracture toughness, un-notched and focused ion beam pre-notched cantilevers were tested. While the thickness of the monolithic cantilevers was varied from 280 nm to 2380 nm, the individual sub-layer thickness of the multi-layer cantilevers was adjusted to 50 nm. Bending experiments reveal a small increase of the fracture stresses with decreasing cantilever thicknesses. For the multi-layer stacks the tensile stress at fracture slightly exceeds the strength values of the corresponding monolithic materials. Furthermore, it is demonstrated that the specimens pre-notched by focused ion beam do not show significant changes in fracture toughness with varying pre-notch size. This makes the applied test a reproducible technique to determine fracture toughness of brittle films.