SiCl4/H2为气源低温沉积多晶硅薄膜低温电学特性的研究

对用SiCl4/H2为源气体、采用等离子体增强化学气相沉积(PECVD)技术制备的多晶硅薄膜进行了低温电学特性的研究.实验结果表明,多晶硅薄膜的暗电导强烈依赖于温度,在300～90K的温度范围内呈现不同的导电特性.对多晶硅薄膜,其导电特性还与晶化率有关,晶化率越大电导率越大.测量数据表明,低晶化率薄膜电输运主要由电子热发射跃过势垒所贡献,但对于高晶化率的薄膜要同时考虑电子隧穿对电导的影响.     

SiO2层上沉积的纳米多晶硅薄膜及其特性

采用低压化学气相沉积(LPCVD)系统以高纯SiH4为气源,在p型10.16 cm<100>晶向单晶硅衬底SiO2层上制备纳米多晶硅薄膜,薄膜沉积温度为620℃,沉积薄膜厚度分别为30 nm、63 nm和98 nm.对不同薄膜厚度的纳米多晶硅薄膜分别在700℃、800℃和900℃下进行高温真空退火.通过X射线衍射(XRD)、Raman光谱、扫描电子显微镜(SEM)和原子力显微镜(AFM)对SiO2层上沉积的纳米多晶硅薄膜进行特性测试和表征,随着薄膜厚度的增加,沉积态薄膜结晶显著增强,择优取向为<111>晶向.通过HP4145B型半导体参数分析仪对沉积态掺硼纳米多晶硅薄膜电阻I-V特性测试发现,随着薄膜厚度的增加,薄膜电阻率减小,载流子迁移率增大.     

金属Cu诱导层对热丝法制备多晶硅薄膜微结构的影响

采用热丝化学气相沉积法(HWCVD),在金属铜诱导层上成功制备出横向晶粒尺寸在1μm左右、垂直晶粒尺寸达20μm的柱状多晶硅薄膜,其晶化率在95%以上.使用XRD、Raman光谱、扫描电子显微镜(SEM)等分析测试手段研究了灯丝温度在1500～1800℃之间变化时,金属铜诱导层对多晶硅薄膜的微观形貌、结晶性及晶体学生长方向的影响规律.结果表明:金属铜诱导层的引入,在一定温度范围内改善了晶粒尺寸,改变了多晶硅薄膜的择优取向,降低了薄膜的晶化温度,提高了晶化率.     

玻片基板温度对磷掺杂真空蒸镀多晶硅薄膜的影响

为进一步提高多晶硅薄膜的晶化率,采用真空蒸镀法结合金属铝诱导退火处理在玻璃衬底上制备了掺杂磷的多晶硅薄膜。采用扫描电镜、激光拉曼光谱仪等研究了基板温度对磷掺杂多晶硅薄膜的组织、形貌、晶粒尺寸及晶化率的影响。结果表明:随基板温度升高,薄膜的晶粒大小和晶化率呈先增大后减小的趋势,基板温度为150℃时,晶粒尺寸显著增大,达0.45μm左右,且具有较高的结晶度,薄膜晶化率可高达94.95%。     

铝诱导非晶硅薄膜快速低温晶化研究

采用金属铝诱导晶化非晶硅薄膜的方法制备多晶硅薄膜。研究了不同的退火温度对a-Si薄膜晶化的影响，采用XRD，Raman，SEM等测试手段分析了实验结果。实验结果发现非晶硅薄膜在400℃下退火20min薄膜仍为非晶结构（a-Si），在450℃下退火20min后非晶硅开始晶化且随着温度的升高，且晶化程度加强。     

新型三明治结构铝诱导非晶硅薄膜低温晶化增强

本文对比探索了新型Al/α -Si/Al三明治结构与传统的Al/α -Si双层结构对铝诱导非晶硅薄膜低温晶化结果的影响,结果表明在相同的制备及退火条件下,前者更利于形成高度晶化的多晶硅薄 .膜.本研究工作利用拉曼光谱、掠入射X射线衍射、光学显微镜、方块电阻等表征方法探讨了薄膜厚度比和退火温度对金属诱导非晶硅薄膜晶化的程度、晶体结构以及电学性能的影响,最终制备出了电阻率仅为2.5 Ω·cm的多晶硅薄膜.     

多晶硅薄膜的铝诱导晶化法制备及其晶粒的择优取向特性

采用铝诱导非晶硅薄膜晶化技术制备了多晶硅薄膜,并研究了多晶硅的成核和生长特性。非晶硅薄膜采用等离子体增强化学气相沉积法制备,其表面沉积铝薄膜后经不同温度的氮氛围退火处理。结果表明,退火后的硅薄膜层与铝层发生置换,所生长的多晶硅颗粒的平均尺寸约为150nm。X射线衍射分析结果揭示,薄膜的晶向显著依赖于退火温度,较低温度下,铝诱导晶化速率较慢,薄膜的优化晶向与非晶硅薄膜中团簇的初始原子排列趋势紧密相关。而较高温度下,铝诱导晶化促使多晶硅(111)择优成核及随后的固相生长。     

铝诱导晶化P型非晶硅薄膜实验研究

利用PECVD设备在普通玻璃基片上沉积硼掺杂P型非晶硅薄膜,采用铝诱导晶化法（AIC）在氮气气氛保护下进行退火处理制备出P型多晶硅薄膜,研究了不同厚度的金属铝膜和热处理温度对非晶硅薄膜的微观结构、表面形貌的影响。实验结果表明：铝膜相对厚度越厚,对a—Si的晶化诱导效果则越好,在一定温度条件下,相对较厚的铝膜可以缩短a—Si晶化为polv-Si的时间,并且能使a—Si的晶化更加完整,产生尺寸较大的硅晶颗粒。在铝膜厚度相同,退火温度相同的条件下,热处理的时间越长,则晶化发生的程度越深,晶化越为彻底。     

薄膜厚度和退火温度对纳米多晶硅薄膜特性影响

以高纯SiH4为气源,采用低压化学气相沉积方法在p型〈100〉晶向单晶硅上620℃制备纳米多晶硅薄膜,对不同薄膜厚度纳米多晶硅薄膜分别在700、800、900℃进行高温真空退火,通过X射线衍射(XRD)、Raman光谱(Raman)、场发射扫描电子显微镜(SEM)和原子力显微镜(AFM)研究薄膜厚度、退火温度对薄膜结晶取向、表面形貌等结构特性影响。结果表明,随薄膜厚度增加,薄膜取向显著且多晶特征明显,沉积薄膜多晶取向为〈111〉、〈220〉和〈311〉晶向,择优取向为〈111〉晶向,TO模强度减弱且加宽,晶粒大小增加;同一薄膜厚度,随真空退火温度升高,X射线衍射峰强度增强,TO模强度增强。     

氢等离子体加热法晶化a-Si:H薄膜

利用氢等离子体加热晶化n^ -a-Si：H／a-Si：H薄膜．可以在450℃的衬底温度下制备多晶硅薄膜。采用X射线衍射谱、Raman散射谱和扫描电子显微镜等手段进行表征和分析,研究了不同退火条件对薄膜晶化的影响。结果表明。随着射频氢等离子功率的提高、衬底温度升高和退火时间的增加,薄膜的晶化度呈现出增加趋势。     

SiNx薄膜中硅纳米粒子的制备及表征

通过等离子增强化学气相沉积(PECVD)法, 以氨气和硅烷为反应气体, P型单晶硅和石英为衬底, 低温下(200℃)制备了含硅纳米粒子的非化学计量比氮化硅(SiN_x)薄膜. 经高温(范围500~950℃)退火处理优化了薄膜结构. 室温下测试了不同温度退火后含硅纳米粒子SiN_x薄膜的拉曼(Raman)光谱、光致发光(PL)光谱及傅立叶变换红外吸收(FTIR)光谱, 对薄膜材料的结构特性、发光特性及其键合特性进行了分析. Raman光谱表明. SiN_x薄膜内的硅纳米粒子为非晶结构. PL光谱显示两条与硅纳米粒子相关的光谱带, 随退火温度的升高此两光谱带峰位移动方向相同. 当退火温度低于800℃时, PL光谱峰位随退火温度的升高而蓝移. 当退火温度高于800℃时, PL光谱峰位随退火温度的升高而红移. 通过SiNx薄膜的三种光谱分析发现薄膜的光致发光源于硅纳米粒子的量子限制效应. 这些结果对硅纳米粒子制备工艺优化和硅纳米粒子光电器件的应用有重要意义.     

Crystallization of amorphous Si thin films by the reaction of MoO3/Al nanoengineered thermite

In this work, we investigated a new crystallization method for amorphous silicon (a-Si) using a mixture of nano-energetic materials: molybdenum oxide and aluminum (MoO₃/Al). The purpose of using nano-energetic materials is to improve the performance of a-Si films with a self-propagating exothermic reaction over a period of microseconds without any substrate damage. The mixture of MoO₃/Al nanopowders was used for a thermite reaction for crystallization of a-Si thin films.Characterization results showed that a-Si thin films were successfully crystallized to poly-Si as evidenced by a Raman peak near 519 cm^− 1. The crystalline volume fraction of poly-Si after the nanoengineered thermite reaction was about 94.7% and poly-Si grains was uniformly distributed with an average grain size of around 40-50 nm. These results indicate that high quality poly-Si thin films were successfully prepared on the substrate.     

硅薄膜中的结构缺陷研究进展

硅薄膜作为制备硅薄膜太阳电池的重要材料,得到了广泛研究和应用,而硅薄膜中的各种缺陷及缺陷密度则对薄膜电池的转换效率和稳定性有着至关重要的影响。对硅薄膜中的缺陷种类、缺陷研究方法以及缺陷对薄膜性能的影响进行总结,期望对提高和改善硅薄膜质量乃至硅薄膜太阳电池转换效率和稳定性提供一定的指导。     

Piezoresistive properties of nanocrystalline silicon thin films deposited on plastic substrates by hot-wire chemical vapor deposition

The piezoresistive property of n-type and p-type nanocrystalline silicon thin films deposited on plastic (PEN) at a substrate temperature of 150 °C by hot-wire chemical vapor deposition, is studied. The crystalline fraction decreased from 80% to 65% in p-type and from 84% to 62% in n-type films, as the dopant gas-to-silane flow rate ratio was increased from 0.18% to 3-3.5%. N-type films have negative gauge factor (− 11 to − 16) and p-type films have positive gauge factor (9 to 25). In n-type films the higher gauge factors (in absolute value) were obtained by increasing the doping level whereas in p-type films higher gauge factors were obtained by increasing the crystalline fraction.     

Preparation of high quality polycrystalline silicon thin films by aluminum-induced crystallization

High quality polycrystalline silicon (poly-Si) thin films without Si islands were prepared by using aluminum-induced crystallization on glass substrates. Al and amorphous silicon films were deposited by vacuum thermal evaporation and radio frequency magnetron sputtering, respectively. The samples were annealed at 500 °C for 7 h and then Al was removed by wet etching. Scanning electron microscopy shows that there are two layers in the thin films. After the upper layer was peeled off, the lower poly-Si thin film was found to be of high crystalline quality. It presented a Raman peak at 521 cm^− 1 with full width at a half maximum of 5.23 cm^− 1, which is similar to c-Si wafer.     

Rapid crystallization of a-Si:H films with various silicon-to-hydrogen bonding configurations using rapid energy transfer annealing

Hydrogenated amorphous silicon (a-Si:H) films were prepared by changing substrate temperature of plasma-enhanced chemical vapor deposition to induce different contents of monohydride and polyhydride bonds, which were then crystallized into polysilicon (poly-Si) films by rapid energy transfer annealing. Fourier transform infrared and transmission spectra show that the formation of numerous polyhydride bonds increases the hydrogen content and reduces the refractive index of a-Si:H films. The rise in the concentration of polyhydride bonds in as-deposited a-Si:H films can result in the increase of ultraviolet reflectance, small peak shift, and change in full width at half maximum of Raman scattering and X-ray diffraction peaks of the obtained poly-Si films after annealing. These results demonstrate that high-concentration polyhydride bonds can promote the rapid crystallization of a-Si:H and obtain high-crystallinity poly-Si films. Transmission electron microscopy identifies that the poly-Si films have the typical dendrite-like grain structure.     

Novel approach to thin film polycrystalline silicon on glass

Thin (1 μm) a-Si:H films have been deposited on glass at high-deposition rate (8 nm/s) and high substrate temperature (400 °C) by the expanding thermal plasma technique (ETP). After a Solid Phase Crystallization treatment at 650 °C for 10 h, many crystal grains are found to extend over the entire thickness (1 μm) of the polycrystalline silicon (poly-Si) films. This result indicates that the scalable, high-deposition rate ETP method can contribute to increase the potential for a widespread diffusion of poly-Si based thin film solar cells on glass.