大面积多晶硅绒面的制备

采用酸腐蚀法,在小面积(2cm×2cm)多晶硅绒面制作的基础上,成功地在大面积(10cm×10cm)多晶硅片表面上制作了绒面.利用扫描电子显微镜(SEM)观察其表面形貌并进行反射谱测试,结果表明腐蚀比较均匀,表面减反射效果较好,加权反射率可以达到5.26%,其减反射效果对入射光波长选择性不明显,远好于工业生产用的SiN减反膜.     

低温酸刻蚀对多晶硅表面织构化的影响

采用低温酸刻蚀,通过优化HF-HNO3-H2O腐蚀溶液体系配比及相关工艺参数,在多晶硅材料的表面制备了绒面结构,并进行SEM表面形貌分析和反射谱的测试。结果表明,低温刻蚀比常温刻蚀在生产工艺中更有利于控制反应速度,从而得到效果较好的绒面结构。研究中发现,在不同HF-HNO3-H2O腐蚀溶液体系配比中,温度对反应速率的影响有较大差异,当HNO3含量相对较低时,低温刻蚀工艺有较好的效果。所得最佳绒面制备方案为:酸腐蚀溶液体系配比为VHF∶VHNO3∶VH2O=1∶4∶2,温度为3℃,反应速率控制为2.6μm/min。该方案已在25MW多晶硅太阳电池生产线上实施,不增加工艺难度和生产成本,适合于工业生产。     

多晶Si太阳电池表面酸腐蚀制绒的研究

研究了采用HF和HNO3非择优腐蚀多晶硅表面制备绒面的机理。通过实验分析了酸混合液的体积浓度配比、添加剂、温度和时间等因素对腐蚀速率和腐蚀后表面形貌的影响;总结出了多晶Si的酸腐蚀规律,得到了制备理想绒面的酸混合液体积配比(V(HF):V(HNO3):V(CH3COOH)=1∶12∶6)。在此基础上提出了优化设计方案:采用廉价的水代替醋酸作为缓蚀剂,腐蚀过程置于超声槽中进行,利用超声波的振动使反应生成的气泡快速脱离多晶Si片表面,同时使腐蚀液浓度分布更加均匀,从而制备出效果更佳的多晶Si绒面。     

低反射率多晶硅绒面的湿法制备研究

在多晶硅太阳电池制备工艺中,多晶硅表面制绒一直是研究热点,绒面的反射率以及形貌受到多个因素的影响。采用由HF,HNO3和H2O组成的腐蚀液对多晶硅进行腐蚀,研究了腐蚀时间,腐蚀液中HF与HNO3的体积比以及H2O在腐蚀液中的含量对制绒结果的影响。用分光光度计测量了制备绒面的反射率,并用扫描电镜观察了制备绒面的表面形貌。研究结果表明,腐蚀液中HF,HNO3和H2O的体积比对腐蚀坑的形貌有重要影响,而腐蚀坑形貌则决定了绒面反射率的高低。当腐蚀液中HF∶HNO3∶H2O体积比为5∶1∶2且腐蚀时间为3 min时,绒面在300 nm～900 nm波长范围内平均反射率最低,仅为20.4%,这是因为绒面中窄而深的腐蚀坑增强了硅片表面对光的吸收,降低了反射率。     

湿法黑硅工艺中银残留对太阳电池性能的影响

采用银金属辅助化学腐蚀技术在多晶硅衬底上制备了黑硅绒面,通过能谱仪、扫描电子显微镜和反射率测试仪对所制备黑硅样品的表面银金属残留、形貌和光吸收进行了表征和分析。在此基础之上,通过扩散、腐蚀清洗、镀膜和印刷烧结测试等工序,将多晶黑硅样品制备成太阳电池片,并通过I-V和EL测试仪对其光伏性能和电致发光特性进行了测量和分析。结果表明,与无银残留样品规则、均匀的圆形腐蚀坑绒面相比,黑硅制备过程中如果有银离子残留在表面,扩孔后的表面形貌呈现为方向杂乱和深浅不一的凹坑状形貌,且凹坑周围边界尖锐、形状不规则,制备成电池后转换效率偏低3.03%。     

NaOH-NaClO腐蚀液制备太阳电池用多晶硅绒面的研究

介绍了一种采用NaOH-NaClO混合腐蚀液制备多晶硅绒面的新方法。研究结果表明,当VNaOH:VNaClO=1:3,NaOH浓度为17%,腐蚀温度为80℃,腐蚀时间为20min时,能够得到均匀的沟壑状凹坑多晶硅绒面,腐蚀后硅片表面的反射率与未腐蚀的硅片表面的反射率相比,降低近30%。另外,与传统的HF:HNO3酸腐蚀工艺相比,这种新型腐蚀工艺不仅可以获得反射率更低的多晶硅绒面结构,而且反应过程中产生的具有高度活性的氯离子可以作为很好的吸杂剂,降低一些有害的金属杂质的活性以提高太阳电池的开路电压,同时也省去了在产业化生产过程中的盐酸处理,从而改善了生产环境。     

碱液环境下电化学腐蚀多晶硅的研究

主要介绍了在NaOH溶液中,利用电化学技术腐蚀制备多晶硅绒面的新方法。实验中,通过改变腐蚀液浓度、腐蚀电压、腐蚀温度等因素,制得一系列多晶硅绒面。实验结果表明,当腐蚀碱液浓度为20%,腐蚀电压为20V,腐蚀温度为25℃时,腐蚀得到的硅片表面比较均匀,在波长400～800nm范围内,测量得表面反射率最低为19%左右。     

低成本多晶硅片表面织构的研究

采用化学腐蚀液织构了经磷吸杂处理后的多晶硅片。利用SEM分析了化学腐蚀后多晶硅表面形态,并通过反射谱测试分析了多晶硅片表面的陷光效果。实验结果表明：经酸腐蚀后的样品表面分布着均一的“蚯蚓状”的腐蚀坑,且反射率较低。在400-1000nm波长范围内,反射率可达22．75％;生长了SiN,薄膜后,反射率减小至8．33％,比原始硅片的反射率低20．96％。     

多晶太阳能电池制绒工艺优化

采用酸溶液腐蚀法研究多晶硅电池绒面性质,改变腐蚀液中HF、HNO_3和去离子水比例和反应时间,通过扫描电镜、反射谱仪、太阳能电池测试系统等手段研究腐蚀液的改变对电池性能的影响。结果表明:HF(40%):HNO_3(65%):H_2O体积比为3:1∶2时其反应速率最高,刻蚀30s时多晶硅刻蚀效果最优,电池光电转换效率最大为18.24%。并对实际生产中药液的使用寿命进行探究,结果表明:生产156mm×156mm多晶硅片,酸腐蚀液刻蚀43万片时多晶硅电池效率最高,超过45万片需要维护或重新配置药液,才能保证电池性能不受影响。     

表面活性剂对硅腐蚀效果及太阳电池性能改善研究

在硝酸/氢氟酸腐蚀液中加入表面活性剂对多晶硅片进行了腐蚀,并使用扫描电子显微镜和激光共聚焦显微镜观察硅片表面形貌的变化,在此基础上分析了硅片浸润性及反应物迁移率变化对腐蚀效果的影响。实验结果表明:加入表面活性剂后,腐蚀速率降低,在硅片表面形成了更均匀的绒面结构及亚微米结构,硅片的反射率从23%下降到18.5%,反射率的降低提升了太阳电池的受光面积。仿真结果表明,使用加入表面活性剂的腐蚀液后制备的太阳电池,其短路电流提升了0.25mA/cm2,光电转换效率提升了0.1%。     

Inorganic Drug‐Delivery Nanovehicle Conjugated with Cancer‐Cell‐Specific Ligand

The surface of layered double hydroxide nanoparticles, a potential drug‐delivery nanovehicle, is modified with the cancer‐cell‐specific ligand, folic acid. The surface modification is successfully accomplished through step‐by‐step coupling reactions with aminopropyltriethoxysilane and 1‐ethyl‐3‐(3‐dimethyl aminopropyl)‐carbodiimide. In order to evaluate the cancer‐cell targeting effect of folic‐acid‐grafted layered double hydroxide utilizing fluorescence‐related assay, both layered double hydroxide with and without folic acid moiety are labeled with fluorescein 5′‐isothiocyanate. The uptake of layered double hydroxide and folic acid conjugated into KB and A549 cells is visualized using fluorescence microscopy and measured by flow cytometry. Both chemical and biological assay results demonstrate that the folic acid molecules are indeed conjugated to the surface of layered double hydroxide and thus the selectivity of nanovehicles to cancer cells overexpressing folate receptors increases. In this study, it is suggested that layered double hydroxide nanoparticles can be used as drug‐delivery carriers with a targeting function due to the chemical conjugation with specific ligand.     

The temperature dependence of ideal gain in double diffused silicon transistors

Theoretical treatments predict higher injection efficiency for double diffused silicon transistors than the experimentally observed values. This paper shows that the discrepancy can be partly explained by the difference in the effective energy gaps in the emitter and base regions. Coulomb interaction of the free carriers results in lower energy gap in the heavily doped emitter than in the rest of the transistor. The difference in the energy gaps is experimentally determined from the activation energy difference of the emitter-current and the ideal component of the base Current. It is concluded that too much doping in the emitter lowers the transistor gain, increases the temperature dependence of the gain, and results in a higher excess noise.     

Studies on Chemical Modification of Porous Silicon‐Based Graded‐Index Optical Microcavities for Improved Stability Under Alkaline Conditions

Preparation of graded‐index optical microcavities based on porous silicon is demonstrated, and chemical modifications for obtaining improved stability under alkaline conditions are studied. Four surface modification methods for stabilizing the samples are examined, and the effects on the optical properties are verified. Two different thermal carbonization treatments resulting in hydrophilic and hydrophobic surfaces are employed. In addition, modification with undecylenic acid is performed on as‐prepared and thermally hydrocarbonized porous silicon surfaces. Stability and sensing capabilities of the modified samples are examined by subjecting them to different concentrations of methylamine and trimethylamine vapors. Vapor induced changes in the reflectance spectra are used for evaluating sensitivity and stability. Sensitivity towards ethanol vapor is also measured in order to compare the sensitivity to a normal organic solvent. The results show that the two carbonization treatments and the undecylenic acid functionalization of the hydrocarbonized surface result in greatly improved stability. In contrast, derivatization of as‐prepared porous silicon with undecylenic acid does not protect the surface sufficiently against oxidation under the highly basic conditions produced by the amine vapors. Surface chemistry is also shown to have a large effect on sensitivity towards the examined vapors. X‐ray photoelectron spectroscopy was used to assess changes in elemental composition of sample surface. The results suggest that thermally promoted addition of undecylenic acid on hydrocarbonized porous silicon is an effective method for producing highly stable optical structures with a carboxyl group functionalization.     

Al-Mg系铝合金脉冲激光焊接性能影响因素分析

为了研究铝合金表面状态和焊接工艺方法对焊接接头性能的影响,采用Nd:YAG脉冲激光器对Al-Mg系铝合金激光焊接方法进行了理论分析和实验验证,得到了焊接接头性能实验结果.结果表明,原始表面和碱蚀表面处理的试样焊接过程不稳定,阳极氧化试样焊接中形成了稳定的小孔效应,焊接过程较稳定;阳极氧化、两面焊、填粉焊都能有效提高焊缝熔深和深宽比;试样阳极氧化、双面焊、填粉焊可使焊缝抗拉强度提高1倍以上,其中Al-0.05Si填粉焊提升效果最好;表面处理试样硬度都有所提高,磷酸阳极氧化提高效果最好.双面焊工艺使焊缝和熔合区硬度提高,填粉焊焊缝中心硬度很低但熔合区硬度提高明显,双面焊、填粉焊热影响区硬度低于单面焊.阳极氧化表面处理、双面焊工艺可以有效地改善Al-Mg铝合金的激光焊接性.     

Physical and electrical characteristics of HfN gate electrode for advanced MOS devices

In this letter, the physical and electrical properties of physical vapor deposited (PVD) hafnium nitride (HfN) is studied for the first time as the metal gate electrode for advanced MOS devices applications. It is found that HfN possesses a midgap work function in tantalum nitride (TaN)/HfN/SiO/sub 2//Si MOS structures. TaN/HfN stacked metal-gated MOS capacitors exhibit negligible variations on equivalent oxide thickness (EOT), leakage current, and work function upon high-temperature treatments (up to 1000 /spl deg/C), demonstrating the excellent thermal stability of HfN metal gate on SiO/sub 2/. Our results suggest that HfN metal electrode is an ideal candidate for the fully depleted SOI and/or symmetric double gate MOS devices application.     

Double beam near-infrared spectrometer for compensation of background water absorption and instrumental drift in intensity

A double beam near-infrared spectrometer is developed to compensate the water absorption and instrumental drift in intensity. The spectrometer may be used for both single and double beam measurements,and the two operation modes are compared. The results show that the double beam technique eliminates instrumental drift in the single beam measurement and therefore the stability of the system increases by more than 20%. The compensation of the double beam system on water absorption is verified by the measurement of fat content in milk. The results show that the spectrum data based on double beam mode get better calibration model and lower prediction error than traditional single beam mode.     

新的质子源质子交换制作的Z切LiNbO3光波导特性

研究了用己二酸和苯甲酸的不同混合摩尔比作为质子源交换制作的Z切LiNbO3光波导的表面折射率改变、波导深度、折射率分布等光学特性。结果表明，在交换温度为230℃，交换时间为6h时，混合摩尔比较高时，波导为β4相；较低时，为β3相。在β4相时，混合摩尔比越大，波导的表面折射率改变和波导的深度越大；在β3相时，不同的混合摩尔比交换的波导光学特性差别不明显。用双晶X射线衍射法对单苯甲酸和混合摩尔比为60％制作的光波导进行X射线衍射。以上结果对波导器件的制作及理解波导折射率改变的物理机制提供了一些有用的信息。     

双路闭环谐振式微光学陀螺

通过建模仿真,从改善陀螺输出带宽以及提高互易性噪声抑制能力出发,对单路闭环谐振式微光学陀螺(R-MOG)和双路闭环R-MOG进行了分析研究。相比于单路闭环R-MOG,双路闭环R-MOG在抑制互易性噪声的同时,能较好地改善输出带宽,并进一步提高陀螺系统的线性度。在此基础上,搭建了双路闭环R-MOG的实验系统,并进行了陀螺零偏稳定性以及输出响应特性测试。实验结果表明,陀螺1h的零偏稳定性为0.53°/s,在±1000°/s转速范围内,陀螺系统的线性度为99.995%。     

活性炭前处理对双电层电容器性能的影响

制备了沥青焦基活性炭双电层电容器用电极材料,将其分别经水洗、酸洗以及超音速气流粉碎处理。在1 mol/L(C2H5)4NBF4/碳酸丙烯酯电解液体系中进行电化学测试,对比评价了各活性炭前处理方法对电容器电化学性能的影响。结果表明,酸洗后活性炭电极比电容提高7%达到163 F/g,高功率放电性能明显改善,当电流密度由70 mA/g增加到1 A/g时,其电极比电容保持率为88%;活性炭进行超细粉碎后不利于电化学性能的提高。     

微波处理菘蓝种子的子叶发育与生物光子辐射的相关性

比较研究不同时间长度的微波辐照菘蓝种子对种子萌发率、淀粉酶活性、转氨酶活性、蛋白酶活性、蛋白质含量、游离氨基酸含量、总DNA含量、子叶发育状况及其生物光子辐射强度的影响.采用微波辐射浸泡3h的菘蓝(Isatis ind igotica Fort)种子.与对照相比,四种处理均能不同程度提高菘蓝种子萌发率、淀粉酶活性、转氨酶活性、蛋白酶活性,促进蛋白质、游离氨基酸、DNA合成,促进子叶发育,提高了生物光子辐射强度.低剂量微波辐射能提高种子生理生化代谢机能,促进种子萌发和幼苗生长发育,研究发现8 s微波预处理效果最为显著.