近场光学存储器

近场光学存储器采用了纳米高新制作技术,具有极高的读出速度和极高的存储密度。本文介绍了近场光学“头”、近场光学记录方法、记录机理和处理方法以及T比特光盘的制造技术和结构。     

近场光学显微镜及其应用

近场光学显微镜是一种新型超高空间分辨率的光学仪器，它在很多领域都有广泛应用。本文描述了近场光学显微镜的成像原理及结构部件，简要介绍了近场光学显微镜在高分辨率光学成像、高密度储存存储以及近场光谱等领域中的应用。     

用近场光学研究单个细胞的超微结构和光学性质

光学方法是对物理、化学、生物、医学等各种样品进行特性表征、结构和机理研究的重要方法．物体结构的细节则深藏于近场区域内，如化学和生物大分子、细胞表面的超微结构等，其大小在纳米级．常规光学方法由于受到衍射极限的限制，其最高空间分辨率只能达到波长的一半，因此无法进行研究．     

AgOx型超分辨近场结构的非线性光学特性研究

采用共焦Z扫描系统，以λ=532nm．脉冲宽度0．7ns．重复频率15．79kHz的脉冲半导体激光器作为入射光源，研究了AgOx超分辨近场结构(SuperRENS)薄膜样品的非线性光学性质．实验获得了其三阶非线性折射率系数随入射光功率的变化曲线．并与Au，Ag薄膜作了比较．讨论了光致非线性变化过程。结果表明，在聚焦激光作用下．AgOx超分辨近场结构薄膜样品存在一相变点．即解析出纳米Ag颗粒，满足了产生局域表面等离子体的激发和增强效应的条件。     

碲镉汞薄膜的MOVPE生长和特性

报道了在水平、常压ＭＯＶＰＥ实验型生产装置中,采用互扩散多层工艺（ＩＭＰ）,用金属有机化合物ＤＭＣｄ、ＤｉＰＴｅ和元素Ｈｇ,在ＣｄＴｅ和ＧａＡｓ衬底上生长的ＨｇＣｄＴｅ薄膜,其组分和薄膜厚度的均匀性以及ｐ型电学性质,初步达到了目前红外焦平面列阵研制的要求,同时,这种薄膜的生长具有一定重复性。     

具有高品质因数的剪切力扫描近场光学显微镜在液体中的生物成像

基于剪切力的探针-试样间距控制扫描近场光学显微镜用于生物材料在液体中的成像比在空气中难得多。液体的黏性阻尼和软的试样表面要求更高的力检测灵敏度。最近我们试验成功的压电双晶片剪切力检测器结合力反馈技术,可以大幅度提高双晶片的机械谐振品质因数,从而改善在粘滞液体中力检测灵敏度。当双晶片在它的某一本征频率下被激励,通过调节一个适当的反馈力,它的机械谐振品质因数在水中可以从40增强到10^3,因此成像灵敏度获得显著改善。上述力检测技术被用于一些生物试样在液体环境下的拓扑和近场光学成像。所得到的力、相位和光学图像显示了高的成像质量和分辨率。实验结果证明上述装置尤其适宜于近场光学显微镜在生物领域的应用。     

富碲碲化铅薄膜的晶体结构、表面形貌、元素深度分布和中红外光学常数

对由富碲( <1mol.% )碲化铅晶体材料热蒸发制备的薄膜进行了表征.结果表明:薄膜是多晶的,具有NaCl型晶体结构,表面晶粒分布均匀,在膜层的深度方向约 170nm内富碲的组分均匀分布.对比薄膜表面抛光前后的中红外光学常数表明表面散射对薄膜光学性质的影响极小.     

近场光学显微术进展

讨论了近场光学显微术发展及其理论知识,重点介绍了近场光学显微镜的工作原理、构造设计、工作方式等,概述了近场光学显微术的应用领域和应用成果,探讨了近场光学显微术目前存在的主要问题和需要解决的问题。     

转台模式的近场微波成像研究

针对转台模式的这场微波成像进行了深入研究。首先给出了转台模式下图像函数（描述目标的几何特征）与球投影的积分变换关系，并导出了图像函数的精确解。然后从线性系统的角度出发，研究了理想情况和实际情况下转台模式近场微波成像的分辨特性，理想情况下成像系统的点扩散函数（ＰＳＦ）就是狄拉克－函数。ＰＳＦ的数值模拟结果表明：实际情况下，扫描频带越宽分辨率越高。     

Effects of defects on the electronic properties of WTe2 armchair nanoribbons

We have investigated the electronic properties of WTe2 armchair nanoribbons with defects.WTe2 nanoribbons can be categorized depending on the edge structure in two types:armchair and zigzag.WTe2 in its bulk form has an indirect band gap but nanoribbons and nanosheets of WTe2 have direct band gaps.Interestingly,the zigzag nanoribbon is metallic while the armchair nanoribbons are semiconducting.Thus they can find applications in device fabrication.Therefore,it is very important to study the effect of defects on the electronic properties of the armchair nanoribbons as these defects can impair the device properties and characteristics.We have considered defects such as:vacancy,rough edge,wrap,ripple and twist in this work.We report the band gap variation with these defects.We have also studied the change in band gap and total energy with varying degrees of wrap,ripple and twist.     

用溶胶-凝胶法制备的Cu2Bi2Cr2O8薄膜 及其光学和铁磁性能研究

以硝酸铜Cu(NO₃)₂·3H₂O、硝酸铬Cr(NO₃)₃·9H₂O、硝酸铋Bi(NO₃)₃·3H₂O和乙二醇为原料,利用溶胶-凝胶工艺在石英衬底上制备了纳米Cu₂Bi₂Cr₂O₈薄膜。通过X射线衍射(X-Ray Diffraction, XRD)和拉曼测试对样品进行了表征。结果表明,Cu₂Bi₂Cr₂O₈薄膜具有良好的光学特性,其禁带宽度为1.49 eV;在磁性测试方面,Cu₂Bi₂Cr₂O₈薄膜呈现出了良好的铁磁性。     

硒化温度对SnSe2薄膜材料性能的影响

采用射频磁控溅射加硒化的两步法在超白玻璃衬底上生长SnSe₂薄膜,采用XRD、光学透过谱、Raman光谱、XPS和SEM等方法对薄膜进行性能表征。通过设置不同的硒化温度,研究不同硒化温度对所得薄膜相结构、物相与组分、表面形貌等性能的影响。结果表明:350℃,40min硒化所得薄膜为片状晶粒,光学带隙为1.46eV,相结构和均匀性等性能在该硒化条件下均为最佳。     

WO3/SnO2复合薄膜的制备及光电性能

采用水热法和电化学沉积法,成功制备了包覆有SnO₂纳米颗粒的WO₃纳米棒阵列薄膜,退火处理后形成WO₃/SnO₂异质结复合薄膜。通过改变SnO₂的沉积时间得到了复合薄膜的最佳制备条件。采用XRD,FESEM对WO₃/SnO₂复合薄膜的物相和形貌进行了分析,通过电化学工作站对WO₃/SnO₂复合薄膜的光电性能进行了研究,结果表明,电沉积时间为120 s时,WO₃/SnO₂复合薄膜具有最小的阻抗,且在0.6 V的偏压下光电流密度为0.46 mA/cm²,相比于单一WO₃纳米棒薄膜,表现出更好的光电化学性能。     

MOS devices with tetragonal ZrO2 as gate dielectric formed by annealing ZrO2/Ge/ZrO2 laminate

A Ge-stabilized tetragonal ZrO₂ (t-ZrO₂) film with permittivity (κ) of 36.2 was formed by depositing a ZrO₂/Ge/ZrO₂ laminate and a subsequent annealing at 600 °C, which is a more reliable approach to control the incorporated amount of Ge in ZrO₂. On Si substrates, with thin SiON as an interfacial layer, the SiON/t-ZrO₂ gate stack with equivalent oxide thickness (EOT) of 1.75 nm shows tiny amount of hysteresis and negligible frequency dispersion in capacitance-voltage (C-V) characteristics. By passivating leaky channels derived from grain boundaries with NH₃ plasma, good leakage current of 4.8 × 10⁻⁸ A/cm² at V_g = V_fb − 1 V is achieved and desirable reliability confirmed by positive bias temperature instability (PBTI) test is also obtained.     

Atomic-layer-deposited Al2O3 and HfO2 on GaN: A comparative study on interfaces and electrical characteristics

Al₂O₃, HfO₂, and composite HfO₂/Al₂O₃ films were deposited on n-type GaN using atomic layer deposition (ALD). The interfacial layer of GaON and HfON was observed between HfO₂ and GaN, whereas the absence of an interfacial layer at Al₂O₃/GaN was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy. The dielectric constants of Al₂O₃, HfO₂, and composite HfO₂/Al₂O₃ calculated from the C-V measurement are 9, 16.5, and 13.8, respectively. The Al₂O₃ employed as a template in the composite structure has suppressed the interfacial layer formation during the subsequent ALD-HfO₂ and effectively reduced the gate leakage current. While the dielectric constant of the composite HfO₂/Al₂O₃ film is lower than that of HfO₂, the composite structure provides sharp oxide/GaN interface without interfacial layer, leading to better electrical properties.     

氮气或氧气气氛退火的氧化铪材料电荷泄漏情况研究

本文中, 使用开尔文探针显微镜,研究了不同退火气氛(氧气或氮气)情况下氧化铪材料的电子和空穴的电荷保持特性。与氮气退火器件相比,氧气退火可以使保持性能变好。横向扩散和纵向泄露在电荷泄露机制中都起了重要的作用。 并且,保持性能的改善与陷阱能级深度有关。氮气和氧气退火情况下,氧化铪存储结构的的电子分别为0.44 eV, 0.49 eV,空穴能级分别为0.34 eV, 0.36 eV。 最后得到,不同退火气氛存储器件的电学性能也与KFM结果一致。对于氧化铪作为存储层的存储器件而言,对存储特性的定性和定量分析,陷阱能级,还有泄漏机制研究是十分有意义的。     

Modeling growth rate of HfO2 thin films grown by metal-organic molecular beam epitaxy

HfO₂ dielectric layers were grown on the p-type Si (100) substrate by metal-organic molecular beam epitaxy (MOMBE). Hafnium-tetra-butoxide, Hf(O·t-C₄H₉)₄ was used as a Hf precursor and Argon gas was used as a carrier gas. The thickness of the HfO₂ film and intermediate SiO₂ layer were measured by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The properties of the HfO₂ layers were evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high frequency (HF) capacitance-voltage (C-V) measurement, and current-voltage (I-V) measurement. C-V and I-V measurements have shown that HfO₂ layer grown by MOMBE has a high dielectric constant (k) of 20-22 and a low-level of leakage current density. The growth rate is affected by various process variables such as substrate temperature, bubbler temperature, Ar and O₂ gas flows and growth time. Since the ratio of O₂ and Ar gas flows are closely correlated, the effect of variations in O₂/Ar flow ratio on growth rate is also investigated using statistical modeling methodology.     

Impact of Cu-rich growth on the Cu2ZnSnSe4 surface morphology and related solar cells behavior

In order to study the influence of Cu-rich growth on the performance of the Cu₂ZnSnSe₄ (CZTSe) thin film solar cells, a multi-stage co-evaporation process is applied. The CZTSe films are grown at a lower substrate temperature to reduce the existence time of Cu_xSe_y at the first period caused by the volatility of SnSe_x. This study examines the surface morphology and device performance in Cu-rich growth and close-to-stoichiometric growth. Although the grain size of Cu-rich growth film increases a little, the difference was not dramatic as the results of CIGS reported previously. A model based on the grain boundary migration theory is proposed to explain the experimental results. The mechanisms of Cu-rich growth between CZTSe and CIGS might be different.     

MgF2/Se薄膜封装层对OLED性能及寿命的影响

有机电致发光器件(OLEDs)在使用过程中,易受到 空气中水汽、氧气及其它污染物的影响从而导致其工作寿命降低。本文将具有良好光透过率 和热稳定性的MgF₂薄膜与在水汽和氧气中具有良好稳定性的Se薄膜通过真空蒸镀制成复 合薄膜作为OLEDs的封装层,以达到提高器件使用寿命的目的。器件各功能层蒸镀完成后, 保持真空度(3×10－4 Pa)不变,在阴极表面蒸镀MgF₂/Se薄 膜封装层。比较 了绿光OLED器件(器件结构为ITO/CuPc/NPB/Alq₃:C-545T/Alq ₃/LiF/Al)封装前后的亮度-电压-电流密度特性、电致发光光谱及寿命。研究 发现,经过MgF₂/Se封装后,器件的电流密度-电压特性、亮度和发光光谱几乎没 有受到影响,二者的光谱峰都在528 nm处,色坐标(CIE)分别为(0.3555,0.6131)和(0.3560,0.6104),只是起亮电压由3V变为4V;器件的寿命由原来的175h变为300h,提高了1.7倍 。因此,MgF₂/Se薄膜是一种有效的OLEDs无机薄膜封装层。