Improved performance of Au nanocrystal nonvolatile memory by N_2-plasma treatment on HfO_2 blocking layer

The N_2-plasma treatment on a HfO_2 blocking layer of Au nanocrystal nonvolatile memory without any post annealing is investigated. The electrical characteristics of the MOS capacitor with structure of Al–Ta N/HfO_2/Si O2/p-Si are also characterized. After N_2-plasma treatment, the nitrogen atoms are incorporated into HfO_2 film and may passivate the oxygen vacancy states. The surface roughness of HfO_2 film can also be reduced. Those improvements of HfO_2 film lead to a smaller hysteresis and lower leakage current density of the MOS capacitor. The N_2-plasma is introduced into Au nanocrystal(NC) nonvolatile memory to treat the HfO_2 blocking layer. For the N_2-plasma treated device, it shows a better retention characteristic and is twice as large in the memory window than that for the no N_2-plasma treated device. It can be concluded that the N_2-plasma treatment method can be applied to future nonvolatile memory applications.     

采用Al/TaN叠层电极提高Si基Ge PIN光电探测器的性能

金属与Ge材料接触由于存在强烈的费米钉扎效应, 导致金属电极与n型Ge接触引入较大的接触电阻, 限制了Si基Ge探测器响应带宽. 本文报道了在SOI衬底上外延Ge单晶薄膜并制备了不同台面尺度的Ge PIN光电探测器. 对比了电极分别为金属Al和Al/TaN叠层的具有相同器件结构的SOI基Ge PIN光电探测器的暗电流、响应度以及响应带宽等参数. 发现在Al与Ge之间增加一薄层TaN可有效减小n型Ge的接触电阻, 将台面直径为24 μ的探测器在1.55 μ的波 长和-1 V偏压下的3 dB响应带宽提高了4倍. 同时, 器件暗电流减小一个数量级, 而响应度提高了2倍. 结果表明, 采用TaN薄层制作金属与Ge接触电极, 可有效钝化金属与Ge界面, 减轻费米钉扎效应, 降低金属与n-Ge接触的势垒高度, 因而减小接触电阻和界面复合电流, 提高探测器的光电性能.     

采用AI／TaN叠层电极提高Si基GePIN光电探测器的性能

金属与Ge材料接触由于存在强烈的费米钉扎效应,导致金属电极与n型Ge接触引入较大的接触电阻,限制了si基Ge探测器响应带宽．本文报道了在SOI衬底上外延Ge单晶薄膜并制备了不同台面尺度的GePIN光电探测器．对比了电极分别为金属Al和A1／TaN叠层的具有相同器件结构的SOI基GePIN光电探测器的暗电流、响应度以及响应带宽等参数．发现在Al与Ge之间增加一薄层TaN可有效减小n型Ge的接触电阻,将台面直径为24um的探测器在1．55um的波长和-1V偏压下的3dB响应带宽提高了4倍．同时,器件暗电流减小一个数量级,而响应度提高了2倍．结果表明,采用TaN薄层制作金属与Ge接触电极,可有效钝化金属与Ge界面,减轻费米钉扎效应,降低金属与n-Ge接触的势垒高度,因而减小接触电阻和界面复合电流,提高探测器的光电性能．     

激光显微拉曼技术检测晶体管工作电流导致的器件自加热现象

随着晶体管尺寸的日益缩小,不良热效应成为晶体管失效重要原因之一.现有的检测器件热分布的手段的空间分辨率较低,不能原位直观地获得这些尺寸越来越小的晶体管的工作过程中的热分布情况.本文针对以上问题,在变温系统上探索利用激光显微拉曼光谱技术原位检测晶体管的自热效应,结果表明可以通过器件衬底上硅的一阶声子振动的拉曼谱峰频率随温...     

硅基低位错密度厚锗外延层的UHV/CVD法生长

利用超高真空化学气相淀积系统, 基于低温缓冲层和插入应变超晶格的方法, 在Si(100)衬底上外延出厚度约为880 nm的纯Ge层. 采用X射线双晶衍射、高分辨透射电镜、原子力显微镜和光致发光谱分别表征了其结构及光学性质. 测试结果显示外延Ge的X射线双晶衍射曲线半高宽为273", 表面均方根粗糙度为0.24 nm, 位错密度约为1.5×10⁶ cm². 在室温下观测到外延Ge的直接带跃迁光致发光, 发光峰值位于1540 nm. 表明生长的Si基Ge材料具有良好的结晶质量, 可望在Si基光电子器件中得到应用.     

循环氧化/退火制备GeOI薄膜材料及其性质研究

采用超高真空化学气相淀积系统在SOI(绝缘体上硅)衬底上生长了Si_0.82Ge_0.18外延层,通过循环氧化/退火工艺,制备出Ge组分从0.24到1的绝缘体上锗硅(SGOI)材料.采用高分辨透射电镜、拉曼散射光谱和光致发光谱表征了其结构及光学性质,对氧化过程中SiGe层中的Ge组分和应变的演变进行了分析.最后制备出11 nm厚的绝缘体上Ge材料(GeOI),具有完整的晶格结构和平整的界面.室温下观测到绝缘体上Ge直接带跃迁光致发光,发光峰值位于1540 nm,发光 关键词： GeOI 氧化 退火 光致发光谱     

Non-homogeneous SiGe-on-insulator formed by germanium condensation process

Ge condensation process of a sandwiched structure of Si/SiGe/Si on silicon-on-insulator （SOI） to form SiGe-on- insulator （SGOI） substrate is investigated. The non-homogeneity of SiGe on insulator is observed after a long time oxidation and annealing due to an increased consumption of silicon at the inflection points of the corrugated SiGe film morphology, which happens in the case of the rough surface morphology, with lateral Si atoms diffusing to the inflection points of the corrugated SiGe film. The transmission electron microscopy measurements show that the non-homogeneous SiGe layer exhibits a single crystalline nature with perfect atom lattice. Possible formation mechanism of the non-homogeneity SiGe layer is presented by discussing the highly nonuniform oxidation rate that is spatially dependent in the Ge condensation process. The results are of guiding significance for fabricating the SGOI by Ge condensation process.     

Analysis of tensile strain enhancement in Ge nano-belts on an insulator surrounded by dielectrics

Ge nano-belts with large tensile strain are considered as one of the promising materials for high carrier mobility metal- oxide-semiconductor transistors and efficient photonic devices. In this paper, we design the Ge nano-belts on an insulator surrounded by Si3N4 or SiO？ for improving their tensile strain and simulate the strain profiles by using the finite difference time domain （FDTD） method. The width and thickness parameters of Ge nano-belts on an insulator, which have great effects on the strain profile, are optimized. A large uniaxial tensile strain of 1.16% in 50-nm width and 12-nm thickness Ge nano-belts with the sidewalls protected by Si3N4 is achieved after thermal treatments, which would significantly tailor the band gap structures of Ge-nanobelts to realize the high performance devices.     

N型掺杂应变Ge发光性质

应变锗材料具有准直接带特性,而且与标准硅工艺兼容,成为实现硅基发光器件重要的候选材料之一.本文基于vandeWalle形变势理论,计算了应变情况下半导体Ge材料的能带结构以及载流子在导带中的分布;通过分析载流子直接带和间接带间的辐射复合以及俄歇复合、位错等引起的非辐射复合的竞争,计算了N型掺杂张应变Ge材料直接带跃迁的内量子效率和光增益等发光性质.结果表明,张应变可有效增强Ge材料直接带隙跃迁发光.在1.5%张应变条件下,N型掺杂Ge的最大内量子效率可以达到74.6%,光增益可以与III-V族材料相比拟.     

Si/SiGe量子级联激光器的能带设计

详细论述Si/SiGe量子级联激光器的工作原理，通过对比找到一组合适的Si，Ge和SiGe合金的能带参数，进而应用6×6 k·p方法计算了不同阱宽、不同Ge组分Si/Si_1-xGe_x/Si量子阱价带量子化的空穴能级本征值及其色散关系，分析Si/Si_1-xGe_x/Si量子阱空穴态能级间距随阱宽和组分的变化规律，最后应用计算结果讨论了Si/SiGe量子级联激光器有源区的能带设计，有益于优化Si /SiGe量子级联激光器结构. 关键词： 硅锗材料 量子级联激光器 子带跃迁 k·p方法')" href="#">k·p方法