以SiCl4/H2为气源低温制备pc-Si薄膜的稳恒光电导特性

研究了以SiCl4/H2为气源、用等离子体增强化学气相沉积方法, 在低于300℃温度下所制备的pc-Si薄膜在长时间的光照下电导率的变化情况.实验结果表明,所制备的多晶硅薄膜具有类稳恒光电导效应,而且薄膜的稳恒光电导特性依赖于薄膜的晶化率和晶粒尺寸,随晶化率的增加和晶粒尺寸的增大而增大.     

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%。     

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.     

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.     

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。     

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。     

以SiCl4为源气体用PECVD技术低温快速生长多晶硅薄膜

报道了以SiCl4和H2为气源,用等离子体增强化学气相沉积技术,在小于300℃的低温下快速生长多晶硅薄膜.实验发现, 生长速率强烈依赖于放电功率、H2/SiCl4流量比和衬底温度, 而薄膜的晶化度只依赖于放电功率和H2/SiCl4流量比,与衬底温度的关系不大.通过控制和选择工艺条件,我们获得了生长速率高达0.35nm/s,晶化度高于75%的多晶硅薄膜.薄膜的暗电导率和光电导率分别达到10-4S-1·cm-1和10-3S-1·cm-1.     

铝诱导晶化真空蒸镀多晶硅薄膜的研究

采用真空蒸镀的方法在玻璃衬底上沉积1层非晶硅薄膜,再通过铝诱导晶化的方法制备出晶粒分布较均匀、晶粒尺寸0.5～5μm、晶化率达到89%的多晶硅薄膜。研究了衬底距离、衬底温度、退火温度对薄膜表面形貌、晶粒尺寸和分布及晶化率的影响。结果表明适中的衬底距离下得到的薄膜晶粒分布均匀,表面平整度好,薄膜厚度较大。薄膜的晶化率随着衬底温度和退火温度的提高而增大;随着退火温度的进一步提高,薄膜的晶化率达到最大值然后降低。     

低温多晶硅薄膜的制备评述

低温多晶硅薄膜晶体管(LTPS-TFT)驱动技术是实现大尺寸全彩平板显示的必由之路.然而,传统的低温多晶硅薄膜制作工艺存在着工序复杂、薄膜均匀性差、可能有金属污染且造价昂贵等问题.因此,有必要研发新一代的低温多晶硅薄膜制备工艺以期进一步提高薄膜质量,降低驱动成本.本文首先介绍了金属诱导横向晶化法(MILC)和准分子激光晶化法(ELA)制备低温多晶硅薄膜的原理,分析了两者各自的优缺点.接着,重点阐述了电感耦合等离子体化学气相沉积法(ICP-CVD)的工作原理和特点,并介绍了目前ICP-CVD在低温多晶硅薄膜制备上所取得的进展.     

锗掺杂真空蒸镀基板距离对多晶硅薄膜的影响

在真空蒸镀多晶硅薄膜中掺入杂质可改善膜的微结构及电特性,目前有关基板距离对所得膜层的影响研究不多。采用真空蒸镀掺杂锗的方法制备出多晶硅薄膜;通过扫描电镜、X射线衍射仪、拉曼光谱仪等研究了基板距离对掺锗多晶硅薄膜的组织、形貌、晶粒尺寸及晶化率的影响。结果表明:随着基板距离的增大,薄膜的晶粒尺寸和晶化率均呈现出先增大后减小的相似趋势;当基板距离为90 mm时,晶粒尺寸显著增大,最大达到0.8μm左右,多晶硅薄膜晶粒形貌、结构性能最好,且具有较高的结晶度,薄膜的晶化率最高可达到85.10%。     

In situ electrical conductivity and the amorphous-crystalline transition in vacuum deposited thin films of Se80Te20 alloy

The electrical conductivity of thin films of Se₈₀Te₂₀ polycrystalline alloy vacuum-deposited at room temperature on glass substrates has been studied duringin situ heating and cooling cycles. From the electron diffraction of as-grown films it is seen that the studied films are amorphous at room temperature. The electrical conductivity and electron diffraction studies showed that the as-grown amorphous thin films undergo an amorphous-crystalline transition in the temperature range 340 to 360 K. Upon cooling, the films appear to undergo a crystalline crystalline transition around the same temperatures. There does not appear to be any dependence of the amorphous-crystalline transition temperature on the thickness of the films. However, high-resistance films (thinner films) have a well-defined transition temperature while the low-resistance films (thicker films) have a broader transition. The electrical conductivity of polycrystalline Se₈₀Te₂₀ films above 360 K appears to be an exponential function of reciprocal temperature.     

Effects of low argon dilution ratio on the nanocrystallization and properties of a-Si:H thin films

The structure and properties of thin films obtained by radio frequency (RF) plasma-enhanced chemical vapor deposition (PECVD) through decomposition of silane mixed with argon have been studied by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, ultraviolet and visible (UV-vis) spectroscopy and transmission electron microscope (TEM), respectively. The dilution ratio increases from 6 to 24, and other deposition parameters are fixed. It is observed that argon as dilution gas in the deposition process benefits the development of nano grains and the growth of thin films. The crystalline volume fraction, grain size and hydrogen content of the films increase with the increase argon dilution ratio. The dark conductivity of the thin films is measured, and the results show that the increase of crystalline volume fraction improves the electrical property of the films. The optical gap of the films is calculated from details of the spectra measured by UV-vis. The decrease of optical gap of the films with the increase of argon dilution ratio has been observed.     

Influence of the substrate temperature on the structure and surface roughness of Cd0.18Sb0.64Te0.18 films

Using a radiofrequency sputtering deposition technique, ternary Cd0.18Sb0.64Te0.18 thin films have been grown on glass substrates at several substrate temperatures (50–250°C). The samples have an Sb content of about 63 at %, as measured by Auger spectroscopy. The surface roughness, the structural and the electrical properties of the films were studied as a function of substrate temperature. X-ray diffraction (XRD) measurements showed that the structure of the films changes from an amorphous phase, when deposited at lower substrate temperatures, to a mixture of two crystalline phases (CdTe and Sb) for higher substrate temperatures. Atomic force microscopy shows an increase in the surface roughness with an increase in the substrate temperature, clearly showing the formation of crystalline phases with microcrystallite sizes in good agreement with those determined from XRD measurements. The amorphous-to crystalline transition is accompanied by an abrupt increase in the room temperature electrical conductivity of the films. This increase in the conductivity as well as its temperature dependence in the range of room temperature to 150°C can be understood in terms of an electrical percolation process through the conducting Sb crystallites.     

Influence of annealing temperature on the properties of polycrystalline silicon films formed by rapid thermal annealing of a-Si:H films

In this work, rapid thermal annealing (RTA) was employed to crystallize the amorphous silicon films deposited by hot-wire chemical vapor deposition. The influence of annealing temperature on structural and electrical properties was studied by Raman spectroscopy, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and temperature-dependent conductivity measurement. The results show that the amorphous silicon films can be successfully crystallized by RTA in a very short time. The crystallinity and electrical properties of the poly-Si films was greatly improved as the RTA temperature increasing. When the temperature higher than 900 °C, the poly-Si films obtained the crystalline fraction above 95 %, and the hydrogen atoms almost disappeared in the poly-Si films. At the temperature of 1,100 °C, polycrystalline silicon films with conductivity of 16.4 S cm^?1 is obtained, which is seven orders in magnitude higher than that of the film annealed at 700 °C.     

Ellipsometry-based conductivity extraction in case of phosphorus doped polysilicon

In this work, we investigated a new method for thin films electrical conductivity extraction based on spectroscopic ellipsometry. This has been enabled through the correlation between the films conductivity and their ellipsometric properties. Indeed, it has been demonstrated that numerous ellipsometric fitting-based approaches can provide, in an indirect way, the electrical characteristics of thin films. The study was focused on electrical conductivity, but doping level or carriers’ mobility can also be extrapolated from ellipsometric measurements. Among various possibilities leading to electrical properties extraction, we can cite the extremal values of Ψ and Δ ellipsometric angles, their associated wavelengths, the mean square error and the maximal and minimal reflectivities ratio. Otherwise, the correlation between extrinsic conductivity and ellipsometric parameters evolution has been confirmed in case of low doping levels with particular behavior after annealing. This contactless method has been successfully applied to polycrystalline silicon films deposited on oxidized, p-type monocrystalline substrates, by low pressure chemical vapor deposition technique, and lightly or heavily phosphorus doped by diffusion. The feasibility of the method has been proven in this case, but also in other cases like implanted polysilicon layers or silicon-on-insulator (not included here).     

Effect of air annealing on structural, optical, microscopic, electrical properties of cadmium selenide thin films

Cadmium selenide films have been deposited on glass substrate dip method. The resultant films were annealed upto 473 K temperature. The structural properties of cadmium selenide thin films have been investigated by X-ray diffraction techniques. The X-ray diffraction spectra showed that cadmium selenide thin films are polycrystalline. As deposited sample shows cubic phase whereas sample annealed at 473 K shows hexagonal phase. The optical properties showed direct band gap values were found to be in the region of 1.82–1.55 eV. The electrical studies shows conductivity increases with increase in annealing temperature. The optoelectric and structural data are discussed from the point of applications based on achieving high performance devices.     

CdxTe薄膜的共蒸发法制备及其表征

采用CdTe和Te双源共蒸发的方法, 调控CdTe和Te源的蒸发速率, 首次制备出一系列不同x组分的Cd_xTe二元化合物薄膜, 并在N₂气气氛下进行185℃退火处理。通过XRD、SEM、紫外-可见吸收光谱分析及暗电导率-温度关系对Cd_xTe薄膜的结构、形貌、光学和电学性质进行表征。紫外-可见吸收光谱分析表明, 不同x组分的Cd_xTe薄膜, 其禁带宽度可在0.99~1.46 eV之间变化, 随着x值从0.8减小到0.2, 吸收边向长波方向移动, 而且透过率也显著下降。XRD结果表明, x值小于0.6时, 刚沉积的Cd_xTe薄膜为非晶相; 随着x的值逐渐靠近1, 刚沉积的薄膜明显结晶, 沿CdTe(111)方向择优生长, 退火处理促使薄膜从非晶转变为多晶。Cd_xTe薄膜的导电类型为p型, 其暗电导率随温度的上升而增大, 当温度继续升高至临界点时, 薄膜暗电导率-温度关系出现反常。这些结果表明, Cd_xTe薄膜将有望用于CdTe薄膜太阳电池以拓展电池的长波光谱响应。     

铝诱导晶化法低温制备多晶硅薄膜

为了满足在普通玻璃衬底上制备多晶硅薄膜晶体管有源矩阵液晶显示器,低温（＜６００℃）制备高质量多晶硅薄膜已成为研究热点．本文研究了一种低温制备多晶硅薄膜的新工艺：金属诱导非晶硅薄膜低温晶化法．在非晶硅薄膜上蒸镀金属铝薄膜,并光刻形成铝膜图形,而后于氮气保护中退火．利用光学显微镜和拉曼光谱等测试方法,研究了Ａｌ诱导下非晶硅薄膜的晶化过程,结果表明;在５６０℃退火６ｈ后;铝膜下的非晶硅已完全晶化,确定了所制备的是多晶硅薄膜．初步探讨了非晶硅薄膜金属诱导横向晶化机理．     

Ni doping effect on electrical conductivity of ZnO nanocrystalline thin films

The electrical conductivity behavior of undoped and Ni-doped ZnO nanocrystalline thin films prepared by spin-coating method was investigated as a function of temperature. The films were found to have polycrystalline structure. Grain size and the conductivity of the films were found to decrease significantly with increase in Ni concentration. This behavior was well explained by the grain boundary conduction model that takes into account electron trapping in surface states. It was observed that by increasing the Ni-doping level the surface trap density increases and implicitly the conductivity decreases.