页岩储层孔隙特征与结构的观察研究

页岩气储层孔隙特征与微观结构对页岩气勘探开发具有重要意义。以五峰组、龙马溪组样品为例,使用常规扫描电镜、氩离子抛光－场发射扫描电镜对孔隙特征、微观结构进行观测,识别出多种成因－形貌孔隙类型,对储层孔隙特征进行了刻画,认为页岩储层孔隙主体处于纳米级别,孔隙形态复杂,类型多样,微裂隙发育;微米级的孔隙与微观结构可以由常规扫描电镜直接观测,而氩离子抛光蚀刻处理有利于纳米级孔隙的定性观测。分析对比了常规扫描电镜、氩离子抛光－场发射扫描电镜试验方法的优势与不足,提出将定性与定量研究手段相综合,在利用扫描电镜系统观测页岩储层孔隙结构的基础上,结合使用高压压汞、气体吸附等定量化方法可以全面描述页岩孔隙特征,是目前对页岩储层孔隙特征进行综合表征的最佳手段。     

HF蚀刻+逐层抛光法表征熔石英亚表面损伤层深度

脆性材料的研磨过程会不可避免地产生亚表面损伤层,对亚表面损伤层的表征和抑制一直是获得高激光损伤阈值熔石英光学元件的关注热点。回顾了几种亚表面有损表征技术,通过实验重新评价了蚀刻表面峰谷(PV)粗糙度法的可行性,分析了其误差较大的原因。在此基础上,提出了一种新的亚表面损伤层深度检测方法——HF蚀刻+逐层抛光法。分别采用这两种表征技术以及粗糙度估计法、磁流变斜面抛光法对不同工艺研磨的熔石英亚表面裂纹深度进行了对比检测,结果表明这几种表征方法相互符合很好。     

基底亚表面裂纹对减反射膜激光损伤阈值的影响

利用化学沥滤技术,分析了亚表面裂纹对基底表面和减反射膜激光损伤阈值(LIDT)的影响。通过去除或保留研磨裂纹,获得了亚表面裂纹数密度有明显区别的两类基底。为了凸出亚表面裂纹层的作用,基底采用化学沥滤去除另外一种可能的影响因素,即再沉积层中的抛光杂质。然后采用电子束蒸发镀制HfO2/SiO2减反射膜。355nm激光损伤阈值测试结果和损伤形貌分析证实了基底亚表面裂纹对减反射膜抗激光损伤能力的负面影响。根据熔石英基底抛光表面的烘烤现象,提出了亚表面缺陷影响膜层激光损伤的耦合模型。     

扫描隧道显微镜重掺硅（111）表面微缺陷研究

利用电化学扫描隧道显微镜（ＥＣ－ＳＴＭ）初步研究了重掺锑硅（１１１）抛光片表面的微结构．多数硅晶片表面不同部位的ＳＴＭ形貌相表明，表面处理过程产生的微缺陷远比晶体生长过程产生的微缺陷多；粗糙度约为几个纳米的大面积平整区域与面积虽小但缺陷密度很高而且无规则分布的微区共存．微缺陷密度与晶体完整性、掺杂浓度和抛光条件有关．轻掺锑硅（１１１）表面相对平整，微结构尺寸较大（１００ｎｍ左右）边缘较平滑；重掺锑硅表面微缺陷密度很高，结构复杂，平整度明显降低．表面机械损伤，杂质条纹，过腐蚀等缺陷密度通过优化表面抛光条件可     

重掺〈100〉硅单晶抛光片条纹状起伏缺陷研究

重掺〈100〉硅单晶片抛光后经微分干涉显微镜观测。抛光片边缘区域存在条纹状起伏缺陷。通过分析条纹状起伏缺陷与重掺硅单品中杂质的分布状况和〈100〉品面本身腐蚀特性的关系，阐述了条纹状起伏缺陷形成的机理。通过工艺试验，对比了不同工艺条件下抛光片表面微观形貌状况，分析了抛光过程中各工艺条件对表面条纹起伏缺陷的影响，采用3步抛光工艺，得到了表面平整和一致性好的抛光片表面，抛光片边缘尤条纹起伏缺陷。     

阵列光开关驱动结构制作工艺的研究

采用KOH溶液湿法腐蚀制作阵列光开关的微反射镜上电极.腐蚀表面的不平整影响了光开关的驱动扭臂结构的制作.采用合理配比的HF,HNO3和CH3COOH腐蚀剂对制作的微反射镜阵列硅片进行抛光处理,抛光后微反射镜表面和腐蚀的(110)面均有较大的改善,并且抛光不影响器件的结构,最后制作出了均匀一致的光开关阵列扭臂驱动结构.     

355nm紫外激光抛光Al_2O_3陶瓷作用机理的实验研究

陶瓷材料的性能优越,但是表面质量差,采用短波长激光抛光技术可以有效提高陶瓷材料表面质量。针对紫外激光抛光Al2O3陶瓷过程中可能存在的熔化、汽化、微裂纹、材料的熔融飞溅和光化学作用等不同的作用形式进行了实验研究。通过对抛光后表面形貌特征进行观测,研究了紫外激光抛光Al2O3陶瓷的作用机理,并分析了高能量密度下产生的白色粉末的形貌、附着力、组成成分和主要物相,进一步确定了紫外激光抛光Al2O3陶瓷的作用机制。     

纳米磨料对GaAs晶片的抛光研究

通过均相沉淀法制备了纳米CeO2和Al2O3粉体,研究了在相同抛光条件下纳米CeO2、SiO2和Al2O3磨料对GaAs晶片的抛光效果,并用原子力显微镜观察抛光表面的微观形貌并测量表面粗糙度。结果表明,使用纳米CeO2磨料抛光后的表面具有最低的表面粗糙度,在1μm×1μm范围内表面粗糙度Ra值为0.740nm,而且表面的微观起伏更趋于平缓。文中还探讨了GaAs晶片化学机械抛光材料去除机理,考虑了纳米磨料在抛光条件下所发生的自身变形,并分析了纳米磨料硬度对抛光表面粗糙度的影响,初步解释了在相同的抛光条件下不同硬度的纳米磨料为什么具有不同的抛光表面粗糙度。     

一维铌酸钠纳米杆的合成及光催化性能

以Nb2O5、NaOH为起始物,NaOH为矿化剂,通过传统水热法并结合后期热处理,成功制备了高结晶度、生长完善的一维正交相NaNbO3纳米结构。采用TG-DSC、XRD和SEM对不同阶段产物的组成、结晶结构、形貌进行了表征。将所制备的Na2Nb2O6·1.4H2O前驱样品在不同温度下热处理,当温度高于400℃时可以转变为一维的正交相NaNbO3纳米杆。随着热处理温度的升高,产物的结晶性保持良好,但其形貌开始发生扭曲甚至出现裂纹。另外,对不同后处理的样品进行光催化产氢测试,结果表明随着热处理温度的增大,一维铌酸钠纳米材料的光催化活性先增大后降低,当后热处理温度为400℃时,平均的产氢率可达104.5μmol·h–1。     

磷化铟单晶衬底的缺陷控制和高质量表面制备

分析研究了一些缺陷对InP单晶衬底的影响,包括团状结构位错的产生及其对晶格完整性的影响,坑状微缺陷、晶片抛光损伤和残留杂质的清洗腐蚀等.对这些缺陷的形成原因和抑制途径进行了分析.在此基础上获得了"开盒即用(EPI-READY)"、具有良好晶格完整性、表面无损伤的InP单晶衬底抛光片.     

抛光工艺对硅基Pb_(1-x)Ge_xTe薄膜性能的影响

研究了不同的抛光方法(机械抛光、化学腐蚀及化学机械抛光)对硅基板上沉积的Pb_(1-x)Ge_xTe薄膜性能的影响.研究表明,经化学机械抛光(SiO_2胶体或Cr~+)的硅基板上所沉积的Pb_(1-x)Ge_xTe薄膜具有致密的结构及平直的界面,其沉积速率也比在化学腐蚀抛光表面的沉积速率大7%或18%(分别对应<111>和<100>晶向);薄膜具有明显高于化学腐蚀抛光基板沉积薄膜的折射率,且折射率随温度的降低而增加,而低温下折射率随波长的增加而增加;化学腐蚀抛光基板沉积薄膜的折射率的增加量明显大于化学机械抛光基板沉积薄膜的增加量;薄膜层经机械抛光后,其膜层结构、组分及其深度分布均未改变,但透射率增加,消光系数有所改善,折射率有所降低.     

Degradation of ZnSe/ZnTe multiquantum well contacts to p-ZnSe

The work presented in this paper studied the degradation of ZnTe/ZnSe multiquantum well contacts to p-ZnSe under high current loading (1000 to 1500 A/cm²). During degradation, localized heating (up to 200°C > the bulk substrate and heat sink) was observed to occur at the point were electrical power was supplied. Auger data from degraded samples indicated that due to the localized heating, Zn and Te from the ZnTe layers and Zn from the ZnSe layer diffused through the Au metallization to the samples surface. In addition, thermal stress from the localized heating generated micro-cracks in the ZnSe which acted as high diffusivity paths for impurities. Rectangular defects were also found to form in the degraded region. These defects were oriented to the micro-cracks and had similar geometries as dislocation patches (dark line defects) which have been reported to form in the quantum well region of degraded ZnSe based laser devices. The similarities between the rectangular defects and dark line defects suggest the formation of similar dislocation patches in the quantum well region of the multiquantum well contacts.     

清洗工艺对锗外延片表面点状缺陷的影响

锗外延片表面的雾、水印及点状缺陷等会影响太阳电池的性能和成品率,其中点状缺陷出现的比例最高。研究了锗抛光片清洗工艺对外延片表面点状缺陷的影响,获得了无点状缺陷、低粗糙度及高表面质量的锗单晶片。采用厚度为175μm p型<100>锗单面抛光片进行清洗试验,研究了SC-1溶液的不同清洗时间、清洗温度和去离子水冲洗温度对锗抛光片外延后点状缺陷的影响,分析了表面SiO_2残留和锗片表面粗糙度对外延片表面点状缺陷的影响。结果表明点状缺陷主要是由于锗单晶抛光片表面沾污没有彻底清洗干净以及清洗过程中产生新的缺陷造成的。采用氢氟酸溶液浸泡、SC-1溶液低温短时间清洗结合低温去离子水冲洗后的锗抛光片进行外延,用其制备的太阳电池光电转换效率由原来的25%提高到31%。     

用于悬浮纳米结构制作的氢氟酸气相刻蚀研究

针对纳米悬浮结构的制作,对不同温度和不同气相条件下的氢氟酸(HF)气相刻蚀进行了研究.利用自制的研究装置,使用HF/水混合气体和HF/乙醇混合气体分别进行了HF对PECVD SiO_2的气相刻蚀实验,同时测量了不同衬底温度下刻蚀速率的变化.研究结果表明,在常温常压下,HF/乙醇混合气体气相刻蚀速率约为7.6 nm/s,而HF/水混合气体气相刻蚀速率约为11.5 nm/s.在衬底温度分别为35,40和50℃时,HF/水混合气体的气相刻蚀速率分别为10.25,7.95和5.18 nm/s.利用HF气相腐蚀进行SiO_2牺牲层释放,得到了悬浮的纳米梁结构,梁与衬底的间距为400 nm.     

Metal-Assisted Chemical Etching Using Tollen’s Reagent to Deposit Silver Nanoparticle Catalysts for Fabrication of Quasi-ordered Silicon Micro/Nanostructures

Metal-assisted chemical etching (MacEtch) of semiconductor materials in HF/H₂O₂ solution using noble-metal particles as catalysts has gained much attention in the past few years due to its unique properties. In this work, nanoscale Ag particles were deposited on (100) and (111) surfaces of polished p-Si wafers through the silver-mirror reaction. Subsequently these wafers were etched in 1:1:1 (v:v:v) HF(49%):H₂O₂(30%):EtOH solution at ambient temperature and pressure for 12 h, producing a number of different quasi-ordered silicon micro/nanostructures. The resulting surface-modified wafers exhibited mixed micro- and nanostructures that are an inherent feature of the etch process; for example, steps appear on the sidewalls of crystallographically defined nanopores, because the catalytic Ag nanoparticles are convected as they transit the developing pore during the etching process. The resulting materials exhibited much reduced reflectivity, reaching a maximum of 3.7× reduction near 330 nm, which renders them of interest in potential applications such as back-reflector templates for deposition of thin-film solar cell materials.     

Impact of Surface Treatment on the Structural and Electronic Properties of Polished CdZnTe Surfaces for Radiation Detectors

We present the effects of surface treatments on the structural and electronic properties of chemomechanically polished Cd_0.9Zn_0.1Te before contact deposition. Specifically, polished CdZnTe (CZT) samples were treated with four distinct chemical etchants: (1) bromine methanol (BM), (2) bromine in lactic acid, (3) bromine in methanol followed by bromine–20% lactic acid in ethylene glycol, and (4) hydrochloric acid (HCl). The surface structure and surface electronic properties were studied with atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). AFM images showed that three of the four etchants significantly altered the surface morphology and structure of CZT. All etchants created smoother surfaces; however, all except HCl also introduced high densities of defects. HCl was found to not affect the surface structure. XPS measurements indicated that a thick, ～3 nm to 4 nm, TeO₂ layer formed about 1 h after etching; hence, it is very important to process devices immediately after etching to prevent oxide formation.     

表面杂质和节瘤缺陷诱导薄膜元件热熔融损伤

在高功率激光系统中,光学薄膜元件表面杂质和体内节瘤缺陷是导致薄膜元件损伤的关键因素。通过建立强激光连续辐照下光学薄膜元件的热分析模型,分析在不同激光辐照时间和功率密度下,表面杂质和节瘤缺陷对光学薄膜元件损伤的影响及其规律。结果表明,在强激光连续辐照下,当表面杂质粒子尺寸处于一定范围内时,随着杂质粒子尺寸的增大,薄膜元件上的最高温度随之升高,且大而浅的节瘤缺陷种子对膜层的温升影响较大。随着激光功率密度的提高和激光辐照时间的增长,表面杂质造成薄膜元件热熔融损伤的粒子尺寸范围越大,节瘤缺陷造成薄膜元件热熔融损伤的种子深度和尺寸范围也越大。     

Study on nano-pores enlargement during Ag-assisted electroless etching of diamond wire sawn polycrystalline silicon wafers

In this paper, diamond wire sawn (DWS) mc-Si wafers were textured using Ag-assisted electroless etching (AgNO₃+HF+H₂O₂) combined with an auxiliary etching (HF+HNO₃). The evolution mechanism of the surface texture structure on the wafers was investigated in detail. It was noted that during the AgNO₃+HF+H₂O₂ etching, there existed the difference in the axial direction and the depth of nano-pores among different grains. This difference made the different grains form different texture structures during the following HF+HNO₃ etching. Since the etching of poly-silicon is isotropic in HF+HNO₃ solution, it was the AgNO₃+HF+H₂O₂ etching rather than the auxiliary etching (HF+HNO₃) that resulted in the different texture structure among different grains. During the HF+HNO₃ etching, the diameter of the etched pits on the wafer surface was enlarged quickly through the adjacent pits combination. The depth of the etched pits hardly increased because the top and bottom of pits were etched at the same time. As a result, the ratio of depth to diameter of the pits decreased. The texture difference among the grains and decrease of the ratio of depth to diameter of the pits limited the further enhancement of the PV efficiency of mc-Si solar cell. Therefore, the improving the uniformity of AgNO₃+HF+H₂O₂ etching for the different crystal orientation grains and obtaining a large ratio of depth to diameter of the pits during the HF+HNO₃ etching are two critical issues to enhance the PV efficiency of mc-Si solar cell.     

Dendrite‐Assisted Growth of Silicon Nanowires in Electroless Metal Deposition

This article concerns the detailed investigations on the silver dendrite‐assisted growth of single‐crystalline silicon nanowires, and their possible self‐assembling nanoelectrochemistry growth mechanism. The growth of silicon nanowires was carried out through an electroless metal deposition process in a conventional autoclave containing aqueous HF and AgNO₃ solution near room temperature. In order to explore the mechanism and prove the centrality of silver dendrites in the growth of silicon nanowires, other etching solution systems with different metal species were also investigated in this work. The morphology of etched silicon substrates strongly depends upon the composition of the etching solution, especially the metal species. Our experimental results prove that the simultaneous formation of silver dendrites is a guarantee of the preservation of free‐standing nanoscale electrolytic cells on the silicon substrate, and also assists in the final formation of silicon nanowire arrays on the substrate surface.