硅含量对SiO_x薄膜光学和电学性能的影响

利用射频磁控溅射法通过调节硅(Si)靶的溅射功率制备了不同的富硅氧化硅(SiOx,1相似文献   

CeF3掺杂增强纳米晶Si光致发光强度的研究

真空蒸发SiO粉末,在Si(100)基体上制备SiOx薄膜,后续氮气中1100 ℃退火制备镶嵌在SiO2基体中的纳米晶Si体系(nc-Si/SiO2),然后将该样品放入真空室,在其上沉积CeF3薄膜,不同温度下热处理使Ce3 扩散到nc-Si附近,实现对纳米晶Si的掺杂.通过改变CeF3薄膜厚度调节掺杂浓度,在一定的掺杂浓度下纳米晶Si的光致发光强度明显改善,激发光谱证实荧光增强机制是Ce3 通过强耦合过程对纳米晶Si的能量传递.     

CeF3掺杂增强纳米晶Si光致发光强度的研究

真空蒸发SiO粉末,在Si(100)基体上制备SiOx薄膜,后续氮气中1100 ℃退火制备镶嵌在SiO2基体中的纳米晶Si体系(nc-Si/SiO2),然后将该样品放入真空室,在其上沉积CeF3薄膜,不同温度下热处理使Ce3+扩散到nc-Si附近,实现对纳米晶Si的掺杂.通过改变CeF3薄膜厚度调节掺杂浓度,在一定的掺杂浓度下纳米晶Si的光致发光强度明显改善,激发光谱证实荧光增强机制是Ce3+通过强耦合过程对纳米晶Si的能量传递.     

制备方法对锌掺杂多孔硅蓝光发射强度及稳定性的影响

分别采用浸渍法和电镀法对多孔硅薄膜进行了锌掺杂.用扫描探针显微镜研究了多孔硅掺杂前后的表面形貌,用荧光分光光度计分析了样品的光致发光特性,发现锌掺杂增强了多孔硅的蓝光发射,且在420nm附近出现了一个小峰,样品放置一个月后,发光强度和峰位变化很小.红外吸收谱表明锌掺杂后,Si-O-Si键、Si2O-SiH键、H2Si-O2键的振动增强,且引入了Zn-O键.锌掺杂多孔硅发射蓝光是由于掺杂后多孔硅无定形程度增大,应力增大,表面进一步被氧化,使纳米硅粒中激发的电子-空穴对在SiOx层中或纳米硅粒与SiOx层界面的发光中心复合发光造成的,420nm处的发光峰是由锌填隙引起浅施主能级上的电子到价带跃迁造成的,同时分析了电镀法掺杂锌的优越性.     

纳米硅镶嵌复合薄膜退火前后的微结构及发光特性研究

采用减压化学气相沉积方法,依靠纯N2稀释的SiH4气体的热分解反应,在玻璃表面生长了纳米硅镶嵌的复合薄膜.实验研究了退火前后薄膜样品的结晶状态和光致发光特性.结果表明,未退火样品的光致发光特性随沉积温度升高反而减弱.退火温度Ta＞600℃时,晶化趋势明显,Ta＜600℃时,退火温度对晶化的贡献不大,但提高退火温度或延长退火时间可以增加PL强度.同时在退火样品中发现Si-Ox的单晶结构.通过Raman、PL、TEM的分析比较,认为在退火前后分别有两种不同的发光机制起主导作用.     

微应变诱导各向异性硅纳米晶形成及其光学特性

通过磁控溅射技术制备了非晶态富硅的碳化硅锗(Si_(1-x-y)Ge_xC_y)薄膜,经过后续高温热处理,形成各向异性硅纳米晶,其微结构和光学特性由高分辨电镜、光致发光及光吸收实验进行表征,研究了各向异性应变对硅纳米晶形态和光学特性的影响,阐述了各向异性硅纳米晶的形成机理。研究表明,在各向异性应变能的诱导下硅纳米晶沿着〈002〉、〈113〉和〈220〉取向择优生长,形成具有多形态的硅纳米晶,显著改变了其能级结构,在2.57eV和2.64eV的位置硅纳米晶存在PL发射光谱,光吸收波段明显增加,可以同时吸收从红外到紫外(2.57eV,1.89eV,1.2eV和0.96eV)的光子,且光吸收范围随硅锗(RS/G)比例可调,故有望提高光伏电池的光量子产额。     

离子注入制备掺Er富硅氧化硅材料光致发光

利用离子注入方法制备了掺Er富硅氧化硅材料,用XRD,TEM方法研究材料微观结构,并测量了样品的光致发光(PL),研究了发光强度随测量温度的变化。试验表明:在1173K以上退火,注入硅集聚,形成φ(2-4)nm的纳米晶硅(nc-Si),纳米晶硅外面包裹非晶硅(a-Si),注入的Er离子分布在非晶硅中。通过非晶硅与硅纳米晶相耦合,非晶硅吸收部分硅纳米晶对Er的激发能量,降低了Er的激发效率;在T>150K时,激发态Er与非晶硅间的能量背迁移降低了Er的发光效率。     

稀土钇掺杂多孔硅光致发光研究

采用电化学方法在多孔硅中掺杂了稀土钇(Y)元素.用荧光分光光度计分析了样品的光致发光特性.多孔硅样品在440nm波长激发下,光致发光谱上主发光峰位于620nm,认为其来源于Si-O复合物的发光中心;多孔硅样品在390nm波长激发下,光致发光谱上主发光峰分别位于527和576nm,并且用量子限制/发光中心模型加以解释.钇掺杂多孔硅样品的光致发光强度明显增强,并且在484nm附近出现新的发光峰.分析结果认为,这是由于钇的掺入,在多孔硅禁带中形成了新的表面能级,从而形成新的发光中心的结果.     

纯无定形氧化硅纳米线热气相法制备及其光致发光性质

在氮气气氛和常压下,采用无金属催化的单步热气相法在单晶硅片上制备大量纯非晶氧化硅纳米线,采用SEM、HRTEM、EDS、XRD和荧光光谱（PL）研究氧化硅纳米线形貌、结构和光致发光性质,并分析其发光中心。结果表明1100℃可形成纳米棒,1200℃则获得光滑均匀纳米线,而1300℃得到的纳米线具有较多弯曲结构,氧化硅纳米线中硅氧原子比接近1∶2,且1300℃制得纳米线中氧含量略高于1200℃,氧化硅纳米线呈无定型态。SiO气化分解和氧化时在硅片上形成氧化硅纳米簇,成为无定形氧化硅纳米线生长的成核中心。氧化硅纳米线的两个光致发光峰值波长为467和364nm,其发光机制是纳米线生长过程中产生的不同点缺陷结构构成了蓝光和紫外光辐射复合中心。     

退火对两种硅基薄膜的结构及发光影响

采用双离子束共溅射沉积方法制备了两种复合硅基薄膜SiOxCy和SiOxNy薄膜,对两种薄膜进行后退火处理,并分别对样品进行PL、FTIR、XPS谱测试分析,比较退火前后的发光及结构的变化。两种样品的光致发光测试谱(PL)表明:退火前后都有两个发光峰位-都存在470nm的发光峰位,它来自于硅基薄膜中中性氧空位缺陷(O3≡Si-Si≡O3),是由于氧原子配位的二价硅的单态-单态之间的跃迁所致,其发光强度随退火温度的升高而变化。进一步的FTIR和XPS的测试谱表明另外一个发光峰位420nm(SiOxCy薄膜)和400nm(SiOxNy薄膜)分别来自于掺杂杂质(C和N)与硅基薄膜中的Si、O组成的复合结构。而两种样品经过退火处理后掺杂所引起的发光峰位强度随退火温度的升高而增强,说明退火温度的升高有利于发光机制的形成。     

Highly Porous Silicon Membranes Fabricated from Silicon Nitride/Silicon Stacks

Nanopore formation in silicon films has previously been demonstrated using rapid thermal crystallization of ultrathin (15 nm) amorphous Si films sandwiched between nm‐thick SiO₂ layers. In this work, the silicon dioxide barrier layers are replaced with silicon nitride, resulting in nanoporous silicon films with unprecedented pore density and novel morphology. Four different thin film stack systems including silicon nitride/silicon/silicon nitride (NSN), silicon dioxide/silicon/silicon nitride (OSN), silicon nitride/silicon/silicon dioxide (NSO), and silicon dioxide/silicon/silicon dioxide (OSO) are tested under different annealing temperatures. Generally the pore size, pore density, and porosity positively correlate with the annealing temperature for all four systems. The NSN system yields substantially higher porosity and pore density than the OSO system, with the OSN and NSO stack characteristics fallings between these extremes. The higher porosity of the Si membrane in the NSN stack is primarily due to the pore formation enhancement in the Si film. It is hypothesized that this could result from the interfacial energy difference between the silicon/silicon nitride and silicon/silicon dioxide, which influences the Si crystallization process.     

Corrosion Characteristics of Silicon Carbide and Silicon Nitride

The present work is a review of the substantial effort that has been made to measure and understand the effects of corrosion with respect to the properties, performance, and durability of various forms of silicon carbide and silicon nitride. The review encompasses corrosion in diverse environments, usually at temperatures of 1000 °C or higher. The environments include dry and moist oxygen, mixtures of hot gaseous vapors, molten salts, molten metals, and complex environments pertaining to coal ashes and slags.     

Silicon spintronics

Worldwide efforts are underway to integrate semiconductors and magnetic materials, aiming to create a revolutionary and energy-efficient information technology in which digital data are encoded in the spin of electrons. Implementing spin functionality in silicon, the mainstream semiconductor, is vital to establish a spin-based electronics with potential to change information technology beyond imagination. Can silicon spintronics live up to the expectation? Remarkable advances in the creation and control of spin polarization in silicon suggest so. Here, I review the key developments and achievements, and describe the building blocks of silicon spintronics. Unexpected and puzzling results are discussed, and open issues and challenges identified. More surprises lie ahead as silicon spintronics comes of age.     

Silicon microdosimetry

Silicon detectors are being studied as microdosemeters since they can provide sensitive volumes of micrometric dimensions. They can be applied for assessing single-event effects in electronic instrumentation exposed to complex fields around high-energy accelerators or in space missions. When coupled to tissue-equivalent converters, they can be used for measuring the quality of radiation therapy beams or for dosimetry. The use of micrometric volumes avoids the contribution of wall effects to the measured spectra. Further advantages of such detectors are their compactness, cheapness, transportability and a low sensitivity to vibrations. The following problems need to be solved when silicon devices are used for microdosimetry: (i) the sensitive volume has to be confined in a region of well-known dimensions; (ii) the electric noise limits the minimum detectable energy; (iii) corrections for tissue-equivalency should be made; (iv) corrections for shape equivalency should be made when referring to a spherical simulated site of tissue; (v) the angular response should be evaluated carefully; (vi) the efficiency of a single detector of micrometric dimensions is very poor and detector arrays should be considered. Several devices have been proposed as silicon microdosemeters, based on different technologies (telescope detectors, silicon on insulator detectors and arrays of cylindrical p-n junctions with internal amplification), in order to satisfy the issues mentioned above.     

Silicon technology

At first a short historical survey is given in chapter 1. That “silicon technology” comprises a totality reaching from heavy machinery down to microscopic operations, is demonstrated in the chapters 2…?5 (production of the material silicon) and 6 (production of devices and integrated circuits). In chapter 7 some applications of these devices in power electronics and in communications- and information-engineering will be described. Finally chapter 8 demonstrates, that in spite of all relevance to power electronics the really very far reaching consequences of silicon technology depend upon its importance to the computer-technics.