在SiO2中掺Al对Au/纳米(SiO2/Si/SiO2)/p-Si 结构电致发光的影响

利用射频磁控溅射方法,制成纳米SiO2层厚度一定而纳米Si层厚度不同的纳米(SiO2/Si/SiO2)/p-Si结构和纳米(SiO2∶Al/Si/SiO2∶Al)/p-Si结构,用磁控溅射制备纳米SiO2∶Al时所用的SiO2/Al复合靶中的Al的面积百分比为1%．上述两种结构中Si层厚度均为1—3nm,间隔为0.2nm．为了对比研究,还制备了Si层厚度为零的样品．这两种结构在900℃氮气下退火30min,正面蒸半透明Au膜,背面蒸Al作欧姆接触后,都在正向偏置下观察到电致发光（EL）．在一定的正向偏置下,EL强度和峰位以及电流都随Si层厚度的增加而同步振荡,位相相同．但掺Al结构的发光强度普遍比不掺Al结构强．另外,这两种结构的EL具体振荡特性有明显不同．对这两种结构的电致发光的物理机制和SiO2中掺Al的作用进行了分析和讨论．     

溅射时间对于Mg_2Si/Si异质结的影响

采用射频磁控溅射沉积并结合热处理制备Mg2Si/Si异质结,研究了溅射时间对Mg2Si/Si异质结的结构以及电阻率的影响。首先在P型Si衬底沉积不同厚度的Mg膜,然后进行低真空热处理,制备不同厚度的Mg2Si/Si异质结。通过XRD、SEM对Mg2Si/Si异质结中Mg2Si的晶体结构、异质结表面和剖面形貌进行分析,结果表明:制备了单一相Mg2Si薄膜,Mg2Si(220)衍射峰最强,异质结界面平整。通过四探针仪测量电阻率进行分析,发现电阻率随Mg2Si膜厚的增加而减小。     

在SiO_2中掺Al对Au/纳米(SiO_2/Si/SiO_2)/p-Si结构电致发光的影响

利用射频磁控溅射方法 ,制成纳米 Si O2 层厚度一定而纳米 Si层厚度不同的纳米 (Si O2 / Si/ Si O2 ) / p- Si结构和纳米 (Si O2 ∶ Al/ Si/ Si O2 ∶ Al) / p- Si结构 ,用磁控溅射制备纳米 Si O2 ∶ Al时所用的 Si O2 / Al复合靶中的 Al的面积百分比为 1% .上述两种结构中 Si层厚度均为 1— 3nm ,间隔为 0 .2 nm .为了对比研究 ,还制备了 Si层厚度为零的样品 .这两种结构在 90 0℃氮气下退火 30 m in,正面蒸半透明 Au膜 ,背面蒸 Al作欧姆接触后 ,都在正向偏置下观察到电致发光 (EL ) .在一定的正向偏置下 ,EL强度和峰位以及电流都随 Si层厚度的增加而     

金属Ni诱导横向晶化Ge纳米点/Si多层异质薄膜的特性

研究了利用低压化学气相沉积(LPCVD)和金属诱导横向结晶技术制备高密度Ge/Si量子点多层异质结构.首先在SiO2/Si(100)衬底上LPCVD生长了高密度Ge/a-Si量子点多层结构,然后在较低温度下(低于550℃),利用金属Ni诱导多层结构中的a-Si层横向结晶制备出高质量的Ge/Si量子点超晶格结构.通过光学显微镜、电子显微镜和显微喇曼光谱等手段测量研究表明,与单一a-Si系统的金属Ni诱导相似,该多层结构中的各α-Si层退火后也具有(110)择优取向,同时晶粒的直径较大,约在4～5μm左右.Ge点中的应力状态的变化揭示出诱导结晶后形成高质量的晶态Si与Ge纳米点界面.     

金属Ni诱导横向晶化Ge纳米点/Si多层异质薄膜的特性

研究了利用低压化学气相沉积(LPCVD)和金属诱导横向结晶技术制备高密度Ge/Si量子点多层异质结构.首先在SiO2/Si(100)衬底上LPCVD生长了高密度Ge/a-Si量子点多层结构,然后在较低温度下(低于550℃),利用金属Ni诱导多层结构中的a-Si层横向结晶制备出高质量的Ge/Si量子点超晶格结构.通过光学显微镜、电子显微镜和显微喇曼光谱等手段测量研究表明,与单一a-Si系统的金属Ni诱导相似,该多层结构中的各α-Si层退火后也具有(110)择优取向,同时晶粒的直径较大,约在4～5μm左右.Ge点中的应力状态的变化揭示出诱导结晶后形成高质量的晶态Si与Ge纳米点界面.     

在SiO2中掺A1对Au／纳米（SiO2／Si／SiO2）／p—Si结构电致发光的影响

利用射频磁控溅射方法,制成纳米SiO2层厚度一定而纳米Si层厚度不同的纳米（SiO2/Si/SiO2）/p-Si结构和纳米（SiO2:A1/Si/SiO2:A1)/p-Si结构,用磁控溅射制备纳米SiO2:A1时所用的SiO2/A1复合靶中的A1的面积百分比为1%。上述两种结构中Si层厚度均为1-3nm,间隔为0.2nm。为了对比研究,还制备了Si层厚度为零的样品。这两种结构在900℃氮气下退火30min,正面蒸半透明Au膜,背面蒸A1作欧姆接触后,都在正向偏置下观察到电致发光（EL）。在一定的正向偏置下,EL强度和峰位以及电流都随Si层厚度的增加而同步振荡,位相相同。但掺A1结构的发光强度普遍比不掺A1结构强。另外,这两种结构的EL具体振荡特性有明显不同,对这两种结构的电致发光的物理机制和SiO2中掺A1的作用进行了分析和讨论。     

磁控溅射的Ge/Si异质结构在退火过程中的Raman光谱研究

用Raman光散射的方法,研究了磁控溅射技术制备的Ge/Si系列异质材料在退火过程中的再生长情况,对不同的样品进行结构变化分析.实验结果显示:Ge/Si异质材料在退火过程中的再生长受生长态条件限制,异质材料的最初生长情况决定了其在退火处理后的结构形态.     

应变SiGe沟道pMOSFET的击穿特性

以半导体器件二维数值模拟程序Medici为工具,模拟和对比了SiGe pMOS同Si pMOS的漏结击穿电压随栅极偏压、栅氧化层厚度和衬底浓度的变化关系;研究了SiGe pMOS垂直层结构参数硅帽层厚度、SiGe层厚度及Ge剂量和p+ δ掺杂对于击穿特性的影响.发现SiGe pMOS击穿主要由窄带隙的应变SiGe层决定,击穿电压明显低于Si pMOS并随Ge组分增加而降低;SiGe/Si异质结对电场分布产生显著影响,同Si pMOS相比电场和碰撞电离具有多峰值分布的特点;Si帽层及SiGe层参数对击穿特性有明显影响,增加p型δ掺杂后SiGe pMOS呈现穿通击穿机制.     

磁控溅射SiGe异质结的薄膜分析

膜层生长不均匀是制备SiGe异质结的研究热点。采用射频磁控溅射方法,通过不断改变溅射时的实验参数,寻找能使Ge纳米薄膜在Si基片上均匀生长的溅射实验条件。实验中,在不同时间条件下分别制备了三种纳米Ge薄膜,通过原子力显微镜对其微观形貌的分析扫描,可以观察到纳米薄膜生长过程中的四个典型阶段,发现Ge/Si的共度生长取得了较好的结果,为SiGe异质结的进一步制备研究奠定了一定的实验基础。     

Raman测量Ge／Si多层膜中Ge晶粒尺寸的理论研究

研究了用磁控溅射方法制备的Gex/Si1-x多层膜的Ge拉曼光谱，在分析了多层膜中Ge微晶的分布和采用微晶壳层 结构假设的条件下，考虑了微晶表面效应的影响，用声子限域模型计算了Ge纳米晶粒的拉曼谱线，拉曼拟合谱线为三条理论谱线的叠加。计算结果表明：在考虑了微晶的表面效应后，拟合结果与实验结果符合得很好。     

溅射参数对Ge2Sb2Te5薄膜光学常数的影响

研究了溅射参数对Ge2Sb2Te5薄膜的光学常数随波长变化关系的影响,结果表明：(1)当溅射功率一定时,随溅射氩气气压的增加Ge2Sb2Te5薄膜的折射率先增大后减小,而消光系数先减小后增大.(2)当溅射氩气气压一定时,对于非晶态薄膜样品,在500nm波长以下,折射率随溅射功率的增加先增加后减小,消光系数则逐渐减小;在500nm以上,折射率随溅射功率的增加逐渐减少,消光系数先减小后增加.对于晶态薄膜样品,在整个波长范围折射率随溅射功率的增加先减小后增加,消光系数则逐渐减少.(3)薄膜样品的光学常数都随波长的变化而变化,在长波长范围变化较大,短波长范围变化较小.探讨了影响Ge2Sb2Te5薄膜光学常数的机理.     

椭圆偏振研究溅射气压对锰膜光学性质的影响

采用射频磁控溅射技术在Si(111)基片上制备金属锰膜,用椭圆偏振光谱在2.0~4.0 e V光子能量范围内研究了溅射压强对锰膜光学性质的影响.分别用德鲁得-洛伦兹模型以及有效介质模型对椭偏参数进行拟合,结果表明随压强增大薄膜致密度先增大后减少;折射率随压强增大先减少后增大;而消光系数随压强的变化与光子能量有关,在低能量区变化复杂,高能量区随压强增加与折射率规律一致.分析表明上述变化与薄膜的致密度密切相关.     

Optical characteristics of Si/SiO2 multilayers prepared by magnetron sputtering

Si/SiO₂ multilayers have been successfully prepared by magnetron sputtering and subsequently thermal annealed in an Ar atmosphere at a temperature of more than 500 °C. The surface of the as-deposited films is compact and smooth, and the distribution of grain size estimated to be 20 nm is uniform. For Si/SiO₂ multilayers annealed at 1100 °C, the Si sublayer sandwiched between potential barrier SiO₂ is crystalline structure by means of the analysis of Raman spectra and XRD data. The visible PL peak accompanying to a blue-shift with the decrease of Si sublayer thickness has been observed, and the intensity of this peak enhances with the increase of annealing temperature. The visible luminescence properties of Si/SiO₂ multilayers can be ascribed to quantum confinement of electron-hole pairs in quantum wells with grain size lower than 4.5 nm. In Si/SiO₂ multilayers, not only quantum confinement but also Si-SiO₂ interface states play an important role in the optical transition. The PL peak located at 779 nm is independent of the thickness of Si sublayer, so it may be ascribed to interface mediated transition. Typical Si dangling bonds defect could be a dominating obstacle to high luminescence efficiencies.     

S枪磁控溅射淀积非晶硅光电导薄膜的制备工艺及特性研究

本文介绍用直流磁控S枪在H_2/Ar混合气体中反应溅射单晶硅靶淀积a-Si:H光电导薄膜的制备工艺。研究了用这种技术制备的a-Si:H薄膜的光学特性(透射率光谱、光学常数和光学带隙等)、晶相结构(用电子衍射图谱)、红外吸收光谱和光电导性能。并讨论了制备工艺条件与薄膜微结构和性能的关系。     

(Si/Ge)n多层薄膜的设计制备及光吸收性能

采用射频磁控溅射技术,在石英玻璃衬底上沉积了具有不同层数和厚度的(Si/Ge)n多层薄膜。XRD、Raman光谱测试表明,溅射态薄膜为微晶结构,在溅射过程中层间扩散形成Si-Ge振动键,溅射时间和薄膜层数影响着薄膜层间的扩散和结晶率;FESEM结果表明,薄膜表面由颗粒团簇构成,层与层之间有明显界面。UV-vis光谱测试表明,(Si/Ge)n多层薄膜在可见光范围内具有较宽的吸收,增加薄膜层数可扩大太阳能光谱的响应范围,而增加Si单层膜厚度对光吸收范围的影响较小。     

硅、锗和氩离子注入富硅二氧化硅的电致发光

将Si、Ge和Ar三种离子注入到磁控溅射制备的富硅二氧化硅和热生长的二氧化硅中,在N2气氛中,作550、650、750、850、950和1050℃退火后,进行电致发光研究.对比样品为退火条件相同的未经注入的上述两种二氧化硅.对于离子注入情况,只观察到Au/1050℃退火的离子注入的富硅二氧化硅/p-Si的电致发光.低于1050℃退火的离子注入富硅二氧化硅和上述各种温度下退火的热生长二氧化硅,无论离子注入与否,都未观察到电致发光.Au/未注入富硅二氧化硅/p-Si的电致发光光谱在1.8eV处出现主峰,在2.4eV处还有一肩峰.在Au/Si注入富硅二氧化硅/p-Si的电致发光谱中,上述两峰的     

Characterization of (CoCr/Pt)20 Namomultilayers Preparation by Magnetron Sputtring

(CoCr/Pt) 20 nanomultilayers with Pt underlayers are prepared by DC magnetron sputtering and the effect of sputtering Ar gas pressure on microstructure and magnetic properties of (CoCr/Pt)20 nanomultilayers is studied.The results show that sputtering Ar gas pressure has a great effect on microstructure,perpendicular magnetic anisotropy,and coercivity of (CoCr/Pt)20 nanomultilayers.For all samples,the effective magnetic anisotropy constant Keff＞0 and all samples have perpendicular magnetic anisotropy.The X-ray diffraction patterns show that low angle X-ray diffraction peaks are very sharp.This confirms the good quality of the multilayers and the bilayer periodicity of films.With increasing of sputtering Ar gas pressure,perpendicular and in-plane coercivity of the samples increase,but the effective magnetic anisotropy constant decreases.The images of atomic force microscopy show that when the sputtering Ar gas pressure is increased,both average grain size and the surface roughness are increased,which lead to the increase of perpendicular coercivity and the decrease of effective magnetic anisotropy constant.     

Lateral photoconductivity of multilayer Ge/Si structures with Ge quantum dots

Spectra of lateral photoconductivity of multilayer Ge/Si structures with Ge quantum dots, fabricated by molecular-beam epitaxy are studied. The photoresponse caused by optical transitions between hole levels of quantum dots and Si electronic states was observed in the energy range of 1.1–0.3 eV at T = 78 K. It was shown that the electronic states localized in the region of Si band bending near the Ge/Si interface mainly contribute to lateral photoconductivity. The use of the quantum box model for describing hole levels of quantum dots made it possible to understand the origin of peaks observed in the photoconductivity spectra. A detailed energy-level diagram of hole levels of quantum dots and optical transitions in Ge/Si structures with strained Ge quantum dots was constructed.     

Visible light emitting Si/SiO2 superlattices

Six-period superlattices of Si/SiO₂ have been grown at room temperature using molecular beam epitaxy. With this mature technology, the ultra-thin (1–3 nm) Si layers were grown to atomic layer precision. These layers were separated by 1 nm thick SiO₂ layers whose thickness was also well controlled by using a rate-limited oxidation process. The chemical and physical structures of the multilayers were characterized by cross-sectional TEM, X-ray diffraction, Raman spectroscopy, Auger sputter-profile, and X-ray photoelectron spectroscopy. The analysis showed that the Si layer is free of impurities and is amorphous, and that the SiO₂/Si interface is sharp (0.5 nm). Photoluminescence (PL) measurements were made at room temperature using 457.9 nm excitation. The PL peak occurred at wavelengths across the visible range for these multilayers. The peak energy position E was found to be related to the Si layer thickness d by E (eV) = 1.60+0.72d⁻² in accordance with a quantum confinement mechanism and the bulk amorphous-Si band gap.     

Lateral photoconductivity of Ge/Si heterostructures with Ge quantum dots

The spectral dependences of the lateral photoconductivity of Ge/Si heterostructures with Ge quantum dots are studied. The photoresponse of the Ge/Si structures with Ge nanoclusters is detected in the range 1.0–1.1 eV at T = 290 K, whereas the photocurrent in the single-crystal Si substrate is found to be markedly suppressed. This result can be attributed to the effect of elastic strains induced in the structure on the optical absorption of Si. At temperatures below 120 K, the heterostructures exhibit photosensitivity in the spectral range 0.4–1.1 eV, in which the Si single crystal is transparent. The photocurrent in this range is most likely due to the transitions of holes from the ground states localized in the quantum dots to the extended states of the valence band.