Research on the fabrication of high performance Au nanocrystal semiconductor memory

金属纳米晶非易失性半导体存储器具有单位面积小、集成密度大、操作电压低、编程速度快、低功耗以及与现存硅技术兼容等优点，有望取代传统浮栅非易失性存储器成为下一代主流的存储器产品，因此进一步提高金属纳米晶半导体存储器的性能具有重要意义。本论文主要围绕提高Au纳米晶半导体存储器的存储能力展开研究，通过对Au纳米颗粒的尺寸、密度、分布等参数的控制及HfO2阻挡层质量的优化，制备出低功耗、大容量的Au纳米晶半导体存储器，为金属纳米晶存储器的应用打下基础。论文的主要工作内容和创新点如下： （1）采用射频磁控溅射结合快速热退火的方法在SiO2/Si结构上制备了Au纳米颗粒，研究了Au纳米颗粒形成的影响因素，...Metal nanocrystal nonvolatile semiconductor memory is a promising candidate to replace the traditional floating gate nonvolatile memory as mainstream flash products due to the advantages of small unit area, high integration density, low operating voltage, fast write/erase speeds, low-power and its compatibility with Si technology. Therefore, improving the performance of metal nanocrystal memory is...学位：工学硕士院系专业：物理科学与技术学院_微电子学与固体电子学学号：1982013115297

基于两步退火法提升Al/n~+Ge欧姆接触及Ge n~+/p结二极管性能

锗（Ge）中高激活浓度、低扩散深度的n型掺杂是实现高性能Ge n-MOSFET的重要前提条件.本文采用低温预退火与脉冲激光退火相结合的两步退火法,结合磷离子注入,制备Al/n+Ge的欧姆接触以及Ge n+/p结二极管.通过电流-电压特性测试来研究Al/n+Ge的欧姆接触以及Ge n+/p结二极管的性能,测试结果表明:低温预退火可初步修复注入损伤,并降低激光退火时杂质的扩散深度;结合离子注入工艺和两步退火工艺,Al/n+Ge欧姆接触的比接触电阻率降至2.61×10-6Ω·cm2,Ge n+/p结二极管在±1V的整流比提高到8.35×106,欧姆接触及二极管性能均得到了显著提升.福建省自然科学基金(批准号:2018J05115);;\n厦门理工学院高层次人才项目(批准号:YKJ16012R);厦门理工学院科研攀登计划项目(批准号:XPDKQ18027);;\n国家自然科学基金青年科学基金(批准号:61704142)资助的课题~

Fabrication and characteristics of high performance SOI-based Ge PIN waveguide photodetector

本文报道了在SOI衬底上外延高质量单晶Ge薄膜并制备高性能不同尺寸Ge; PIN波导光电探测器.通过采用原子力显微镜、X射线衍射、拉曼散射光谱表征外延Ge薄膜的表面形貌、晶体质量以及应变参数,结果显示外延Ge薄膜中存在; 约0.2%左右的张应变,且表面平整,粗糙度为1.12 nm.此外,通过暗电流、光响应度以及3; dB带宽的测试来研究波导探测器的性能,结果表明尺寸为4 mum*20 mum波导探测器在-1 V的反向偏压下暗电流密度低至75; mA/cm~2,在1.55 mum波长处的响应度为0.58 A/W,在-2 V的反向偏压下的3 dB带宽为5.5 GHz.Silicon-based photonics has aroused an increasing interest in the recent year, mainly for optical telecommunications or optical interconnects in microelectronic circuits. The waveguide photodetector is one of the building blocks needed for the implementation of fast silicon photonics integrated circuits. The main considerations for designing such a device are the bandwidth, the power consumption and the responsivity. Germanium is now considered as an ideal candidate for fully integrated receivers based on silicon-on-insulator (SOI) substrates and complementary metal oxide semiconductor (CMOS)-like process because of its large optical absorption coefficient at the wavelength for optical communication. Therefore, the study of high speed and high responsivity Ge waveguide photodetectors is necessary. In this paper, high concentration phosphor doped SOI substrate is achieved by using solid-state source diffusion at first. Secondly, the high quality epitaxial germanium (Ge) is grown on phosphor doped SOI substrate by using low temperature Ge buffer layer technique based on the UHV/CVD system. The surface profile, crystal quality and strain of epitaxial Ge film are characterized by using atomic force microscopy, X-ray diffraction (XRD), and Raman scattering spectrum. The results show that the Ge film has a smooth surface of 1.12 nm roughness and about 0.2% tensile strain, which is verified by XRD characterization result. Thirdly, ptype Ge region is formed by BF2+ implantation, and rapid thermal annealing to repair the implantation damages and activate impurity. Finally, the highperformance Ge PIN waveguide photodetectors with different sizes are fabricated by standard COMS technology. Moreover, the device performances, in terms of dark current versus voltage characteristics, photocurrent responsivity and 3 dB bandwidth, are well studied. The results show that the detector with a size of 4 mu m x 20 mu m demonstrates a dark current density of 75 mA/cm(2) at -1 V and a photocurrent responsivity of 0.58 A/W for 1.55 mu m optical wavelength. In addition, an optical band width of 5.3 GHz at -2 V for 1.55 mu m is also demonstrated, which is far below theortical value of about 40 GHz. This can mainly be attributed to two aspects. On the one hand, Ge PIN structure contains low temperature Ge buffer layer, which has highdensity dislocation because of large lattice mismatch between Si and Ge. Those dislocations or defects can trap and release the photo-generated carrier, which increases the transit time. On the other hand, the contact characteristics of Al with n(+)-Si and p(+)-Ge are not very good, leading to a large contact resistance and RC delay. Through improving the above two aspects, the performance of Ge PIN waveguide photodetector will be further enhanced.High Level Talent Project of Xiamen University of Technology, China; [YKJ16012R

Recent Advances in Big Defensins of Marine Invertebrates

Big defensins are cysteine-rich cationic antimicrobial peptides(AMPs)formed by serially connecting the N-terminal hydrophobic domain with the C-terminal beta-defensin-like domain.These domains have different antibacterial activities.Moreover,big defensins have conserved salt-stable antimicrobial activity and the N-terminal domain can drive the self-assembly of big defensins into nanonetworks that entrap and kill bacteria.So far,big defensins have been mainly found in the innate immune system of invertebrate animals and amphioxus that is a primitive chordate holding a key phylogenetic position bridging from invertebrates to vertebrates.Moreover,the C-terminal domain of big defensins has similar structure and bioactivity to the beta-defensin of vertebrates,which has aroused interest in investigating the biological evolution and function of defensins and the evolution of the immune system in species related to defensins.Based on the progress that has been made in the identification and characterization of big defensins in recent years,herein we present an integrated review of the molecular structures and evolution of big defensins,together with their antibacterial mechanism and expression regulation as well as their application prospects in the fields of aquaculture and aquatic product safety and in the development of new antimicrobial drugs.This review will provide a reference in the application of big defensins