Effect of Chemicals on Chemical Mechanical Polishing of Glass Substrates

We investigate the effect of chemicals on chemical mechanical polishing （CMP） of glass substrates. Ceria slurry in an ultra-low concentration of 0.25 wt. % is used and characterized by scanning electron microscopy. Three typical molecules, i.e. acetic acid, citric acid and sodium acrylic polymer, are adopted to investigate the effect on CMP performance in terms of material removal rate （MRR） and surface quality. The addition of sodium acrylic polymer shows the highest MRR as well as the best surface by atomic force microscopy after CMP, while the addition of citric acid shows the worst performance. These results reveal a mechanism that a long-chain molecule without any branches rather than small molecules and common molecules with ramose abundant-electron groups is better for the dispersion of the slurry and thus better for the CMP process.     

Ge1Sb2Te4 Based Chalcogenide Random Access Memory Array Fabricated by 0.18-μm CMOS Technology

Ge1Sb2Te4-based chalcogenide random access memory array, with a tungsten heating electrode of 260hm in diameter, is fabricated by 0.18-μm CMOS technology. Electrical performance of the device, as web as physical and electrical properties of GelSb2 Te4 thin film, is characterized. SET and RESET programming currents are 1.6 and 4.1 mA, respectively, when pulse width is 100 ns. Both the values are larger than those of the Ge2Sb2 Tesbased ones with the same structure and contact size. Endurance up to 106 cycles with a resistance ratio of about 100 has been achieved.     

带隙可调的CdS纳米晶薄膜的化学浴制备和光学性质

CdS是一种直接带隙半导体,室温下其禁带宽度约为2.4eV,是一种良好的太阳能电池窗口层材料和过渡层材料.分别以CdCl₂和(NH₂)₂CS作为镉源和硫源,用化学淀积法在玻璃上生长CdS纳米薄膜,考察了Cd²⁺浓度、淀积温度、淀积时间以及溶液pH值对CdS成膜的影响.紫外可见光吸收谱和荧光光谱的结果表明,在样品的制备过程中,通过改变反应条件如化学试剂的浓度、加热温度、加热时间等来控制薄膜中颗粒的尺寸大小,随着反应温度的逐渐降低或反应时间的减少等可以使得到的CdS纳米晶薄膜中晶粒尺寸逐渐减小,带隙增加;镉离子浓度越小或氨水浓度越大,所得CdS纳米晶薄膜带隙越大.     

Nanoscale Tapered Pt Bottom Electrode Fabricated by FIB for Low Power and Highly Stable Operations of Phase Change Memory

Phase change random access memory （PC-RAM） based on Si2Sb2Te5 with a Pt tapered heating electrode （Pt-THE）, which is fabricated using a focus ion beam （FIB）, is investigated. Compared with the tungsten electrode, the Pt-THE facilitates the temperature rise in phase change material, which causes the decrease of reset voltage from 3.6 to 2.7 V. The programming region of the cell with the Pt-THE is smaller than that of the cell with a cylindrical tungsten heating electrode. The improved performance of the PC-RAM with a Pt-THE is attributed to the higher resistivity and lower thermal conductivity of the Pt electrode, and the reduction of the programming region, which is also verified by thermal simulation.     

纳米球刻蚀法制备的二维有序的CdS纳米阵列及其光学性质的研究

采用纳米球刻蚀(nanosphere lithography)技术,以自组装的聚苯乙烯纳米小球(polystyrene,PS小球)的单层膜为掩模,制备出二维有序的CdS纳米阵列.利用扫描电子显微镜(SEM)对样品结构进行了表征,用紫外—可见分光光度计对样品光学性质进行了分析.结果表明：制备的二维CdS纳米阵列是高度有序的,且与作为掩模的纳米小球的原始尺寸及排布结构一致;禁带宽度为2.60eV,相对于体材料的2.42eV,向短波长蓝移了0.18eV,表现出CdS材料在纳米结构点阵中的量子尺寸效应;CdS纳米关键词：纳米球刻蚀二维CdS纳米有序阵列     

A 0.18-μm 3.3 V 16 k Bits 1RIT Phase Change Random Access Memory （PCRAM） Chip

Using standard 0.18-μm CMOS process and the special platform for S-inch phase change random access memory （PCRAM）, the first Chinese 16k bits PCRAM chip has been successfully achieved. A 1RIT structure has been designed for low voltage drop and low cost compared to the 1RlD structure and the BJT-switch structure. Full integration of the 16k bits PCRAM chip, including memory cell, array structure, critical circuit module, and physical layout, has been designed and verified. The critical integration technology of the phase change material （PCM） fabrication and the standard CMOS process has been solved. Test results about PCM in a large-scale array have been generated for the next research of PCRAM chip.     

外腔反馈对量子点激光器输出特性的影响

在对光栅外腔量子点激光器进行理论研究的基础上,分析了外腔反馈对Littrow型光栅外腔量子点激光器输出功率、调谐范围等输出特性的影响,发现器件参数的选择对外腔激光器的性能影响很大。对外腔激光器的输出功率和调谐范围进行了理论计算,并与实验结果进行了对比。计算得到的外腔激光器的输出功率与实验结果符合得很好,忽略了非线性增益相关的增益抑制的单模调谐范围理论计算值稍小于实验结果。