Experimental Characterization of the Vertical Position of the Trapped Charge in Si Nitride-Based Nonvolatile Memory Cells

We present a broad set of experiments on silicon nitride-based memories aimed at the investigation of the vertical position of the charge trapped in the nitride layer of silicon-oxide-nitride-oxide-semiconductor (SONOS) memories during program and erase in the tunneling regime. The results obtained for SONOS devices with conventional oxide-nitride-oxide and oxide-nitride-oxide-nitride-oxide gate stacks, as well as with high-top dielectric, have been validated by comparing different characterization techniques. It has been shown that, for SONOS cells, the charge centroid is located in the center of the silicon nitride layer, and its position is quite insensitive to the program or erase conditions and to the gate-stack composition.     

EEPROM耐久和数据保持试验方法标准分析

介绍了存储器分类,论述非易失性存储器编程机理以及编程/擦除耐久和数据保持试验方法,分析了MIL-STD-883B中的《耐久寿命试验》和JESD22-A117《电可擦除可编程只读存储器(EEPROM)编程/擦除耐久和数据保持应力试验》等试验方法标准.     

N型背发射极晶体硅太阳电池模拟研究

N型晶体太阳电池由于少子寿命高、光致衰减低、弱光响应好等优点,近年来在高效率低成本太阳电池领域一直备受关注。利用PC1D模拟,对N型背发射极晶体硅太阳电池进行了分析。结果表明,背发射极掺杂浓度、结深、背表面复合速率、前表面掺杂浓度及复合速率都对电池转换效率有较大影响,尤其是电池前表面与背表面复合速率对电池性能的影响最为明显,而电池前表面场掺杂深度则对电池性能影响较小。对于前表面复合来说,当前表面复合速率小于1×103cm/s时,电池性能受表面复合速率变化的影响很小;但复合速率超过1×103cm/s后,电池转换效率快速下降。背表面复合对电池效率影响则更明显,当背表面复合速率超过1×104cm/s后,电池转换效率急剧下降,在背表面复合速率增大到1×106cm/s时,电池效率下降到不足5%,而在电池背表面复合速度较小时(10~103cm/s)则可获得较高的转换效率。     

含非晶硅薄膜晶体管和液晶象素单元的电路模拟程序

本文主要介绍了一个适用于计算机模拟的非晶硅薄膜晶体管(TFT)和液晶象素单元的电路模拟程序。     

Analysis and Simulation of Vertical Complementary Silicon Bipolar Transistors

The features of modern complementary bipolar technologies (CB-technologies) for analog applications have been analyzed and the main trends in their development are considered. Different industrial CBtechnologies are compared on the basis of two parameters of complementarity, namely the quality factor (βV _A ) and Johnson’s parameter (BV _CEO f _T ). The p-epitaxial-planar CB-technology has been studied by the method of two-dimensional numerical simulation using the TCAD Sentaurus software for vertical n–p–n and p–n–p transistors. A careful calibration of the parameters of technological and electrophysical 2D models on the basis of test structures has shown sufficient accuracy of the used methodology for practice.     

PIN型非晶硅薄膜太阳电池仿真研究

运用AMPS软件,对TCO/p-a-SiC:H/i-a-Si:H/n-a-Si:H/metal型非晶硅薄膜太阳电池进行了仿真研究,重点模拟和分析了电池性能参数随i层和n层厚度变化的规律.结果表明,为了获得电池转换效率和短路电流密度的最大值,n 层非晶硅薄膜应尽可能地减小厚度,而i层非晶硅薄膜厚度最好控制在500～700 nm范围内.     

Numerical Simulation of Bottom Oxide Thickness Effect on Charge Retention in SONOS Flash Memory Cells

In this paper, bottom-oxide thickness (T_bo) and program/erase stress effects on charge retention in SONOS Flash memory cells with FN programming are investigated. Utilizing a numerical analysis based on a multiple electron-trapping model to solve the Shockley-Read-Hall rate equations in nitride, we simulate the electron-retention behavior in a SONOS cell with T_bo from 1.8 to 5.0 nm. In our model, the nitride traps have a continuous energy distribution. A series of Frenkel-Poole (FP) excitation of trapped electrons to the conduction band and electron recapture into nitride traps feature the transitions between the conduction band and trap states. Conduction band electron tunneling via oxide traps created by high-voltage stress and trapped electron direct tunneling through the bottom oxide are included to describe various charge leakage paths. We measure the nitride-charge leakage current directly in a large-area device for comparison. This paper reveals that the charge-retention loss in a high-voltage stressed cell, with a thicker bottom oxide (5 nm), exhibits two stages. The charge-leakage current is limited by oxide trap-assisted tunneling in the first stage and, then, follows a 1/t time dependence due to the FP emission in the second stage. The transition time from the first stage to the second stage is related to oxide trap-assisted tunneling time but is prolonged by a factor     

Model Analysis of Transients in On-Chip Interconnections

Transient processes due to the inductive properties of interconnections are considered. The hierarchy of characteristic physical times is discussed at a qualitative level. From model solutions of the telegraph equations, a perturbation parameter is derived. It allows asymptotic representation in terms of the RLCand RCmodels of interconnections. Associated estimates for submicron technologies are given.     

单晶硅太阳电池纳米减反射膜的研究

报道了用热喷涂工艺制备单晶硅太阳电池纳米减反射膜的研究结果 ,讨论了衬底温度对 Ti Ox 纳米减反射膜结构及折射率的影响 ,优化了热喷涂的工艺条件 ,并研究了 Ti Ox 纳米减反射膜对单体太阳电池效率的贡献。实验证明 ,用热喷涂工艺制备的纳米 Ti Ox 减反射膜可使 1 0 0 mm× 1 0 0 mm单体太阳电池的平均光电转换效率增加 8%～ 9%。     

Photoluminescence Analysis of Iron Contamination Effect in Multicrystalline Silicon Wafers for Solar Cells

We investigated the effect of Fe contamination on the electronic properties of dislocation clusters in relation to oxygen precipitation in multicrystalline silicon (mc-Si). Photoluminescence (PL) spectroscopy and mapping were performed at room and liquid-He temperatures on mc-Si wafers before and after Fe contamination. PL spectra consisted of the band-edge emission, the 0.78-eV emission associated with oxygen precipitates, and the dislocation-related D-lines. The Fe contamination increased the electrically active dislocation clusters. Part of these clusters acted as preferential oxygen precipitation sites, and their electronic properties were not further influenced by the Fe contamination.     

密勒运算跨导放大器的单粒子瞬变效应分析

从2阶闭环系统的角度出发,推导并分析了单粒子瞬变(SET)电流在密勒运算跨导放大器(OTA)中的传导效应。通过理论分析,发现OTA两级跨导比例(Gm2/Gm1)的大小不仅决定了系统闭环的稳定性,也决定了SET电流在系统输出端电压响应的振动幅度和恢复时间。在标准0.18μm CMOS工艺下,通过改变两级跨导的比例值,对电路的两个有效节点进行电路级SET轰击实验,收集实验结果,给出抗SET效应运算放大器的设计建议。     

用于高效太阳电池的硅基微纳结构及制备

介绍了用于高效太阳电池的几种硅基微纳结构的最新研究进展,重点介绍了几种硅基微纳结构的制备方法,如阳极腐蚀制备多孔硅、各向异性制绒以及气液固(VLS)生长纳米线等,并对各种方法的特点作了分析比较,指出了各种方法存在的问题。最后对今后研究的方向做了展望,由于太阳电池在性能提高以及产业应用方面的需求,未来用于高效太阳电池的硅基微纳结构仍是研究的热点之一。进一步提升其对太阳电池效率的优化能力将是研究的重要关注点,而其制备技术也将向着低成本、大规模及可控制的方向发展。     

Progress in Low-temperature Surface Passivation of Silicon Solar Cells using Remote-plasma Silicon Nitride

Using a remote-plasma technique as opposed to the conventional direct-plasma technique, significant progress has been obtained at ISFH in the area of low-temperature surface passivation of p-type crystalline silicon solar cells by means of silicon nitride (SiN) films fabricated at 350–400°C in a plasma-enhanced chemical vapour deposition system. If applied to the rear surface of the low-resistivity p-type substrates, the remote-plasma SiN films provide outstanding surface recombination velocities (SRVs) as low as 4 cm s⁻¹, which is by a clear margin the lowest value ever obtained on a low-resistivity p-Si wafer passivated by a solid film, including highest quality thermal oxides. Compared to direct-plasma SiN films or thermally grown oxides, the remote-plasma films not only provide significantly better SRVs on low-resistivity p-silicon wafers, but also an enormously improved stability against ultraviolet (UV) light. The potential of these remote-plasma silicon nitride films for silicon solar cell applications is further increased by the fact that they provide a surface passivation on phosphorus-diffused emitters which is comparable to high-quality thermal oxides. Furthermore, if combined with a thermal oxide and a caesium treatment, the films induce a UV-stable inversion-layer emitter of outstanding electronic quality. Due to the low deposition temperature and the high refraction index, these remote-plasma SiN films act as highly efficient surface-passivating antireflection coatings. Application of these films to cost-effective silicon solar cell designs presently under development at ISFH turned out to be most successful, as demonstrated by diffused p-n junction cells with efficiencies above 19%, by bifacial p-n junction cells with front and rear efficiencies above 18%, by mask-free evaporated p-n junction cells with efficiencies above 18% and by MIS inversion-layer cells with a new record efficiency of above 17%. All cells are found to be stable during a UV test corresponding to more than 4 years of glass-encapsulated outdoor operation. © 1997 John Wiley & Sons, Ltd.     

太阳电池用多晶硅锭红外检测中阴影的表征分析

研究了多晶硅铸锭过程中,硅锭内部红外探伤测试中显示黑斑位置晶体缺陷的杂质组成,并根据杂质成分推导了此种缺陷的形成机理和条件.采用光致发光(PL)技术、扫描电子显微镜(SEM)和X射线能谱仪(EDS)对杂质进行了表征与分析.结果显示,形成阴影的夹杂在晶界中存在的形态主要为针状或薄片状,其组成成分主要为C,N和Si元素.而Si3N4的出现可能有两个原因:一是Si3N4涂层脱落而沉积在晶界中;二是溶解在液相中的N局部过饱和.此外,结晶过程中,SiC也随之成核并生长,在晶界上形成夹杂物,同时伴随着微缺陷的增加.据此提出了去除多晶硅锭内部阴影的几点措施.     

液晶显示器件模拟程序的编制与测试

文章根据液晶连续弹性体理论、差分迭代法和Berreman的4×4矩阵法,介绍了计算液晶指向矢分布和透过率的数值方法。本次程序的实现采用的是Visual C＋＋,由于在透过率计算中涉及到了exp0函数的幂为复数4×4矩阵,若用C语言则因工作量极大而实现困难。在Matlab中存在函数expm0专门计算幂为矩阵的expO函数,在界面中绘图功能需用到plot函数。综上考虑．做出了Visual C＋＋与Madab接口来实现所需函数脱离于Madab的调用。文章以TN型液晶显示器为例,验证了本软件的正确性．还介绍了本实验室提出的扭曲HAN模式。由于其视角特性尚不明确。利用所编软件．对其液晶盒进行了不同视角下的透过率计算。通过上述计算得到参数的最优设置（△n=0．08（nc=1．556,no=1．476）,d=6μm,po=20μm）,从而获得最大视角,在对比度大于5的基础上．约为-85°到75°。     

硅太阳电池扩散方阻均匀性研究

在规模化生产制作单晶硅太阳能电池过程中,控制扩散质量是提升电池质量和效率的关键。在分析了设备及工艺方面存在的影响扩散均匀性因素的基础上,提出了优化扩散均匀性的实验方法,包括：在硅片表面上制作二氧化硅薄膜来减缓磷扩散的速度;在扩散时控制小氮与氧气的流量比例;减少扩散过程中温度波动对扩散结果的影响;在炉口区域设置较高的温度进行温度补偿;调整炉内压强使输入输出达到动态平衡等。试验证明这些方法可以改善电池电性能,并对工业化生产具有一定的参考价值。     

硅基太阳电池的表面纳米织构及制备

综述了用于硅基太阳电池高效陷光的四种表面纳米织构,即金属纳米颗粒、纳米线、纳米锥和纳米孔。相对于其他三种表面纳米织构,纳米孔具有更好的结构特性和陷光能力。详细介绍了各种表面纳米织构的制备方法,如金属薄膜退火、金属诱导化学腐蚀、干法刻蚀、深紫外光刻和纳米球光刻等。通过表面纳米织构提高效率是太阳电池领域的重点研究内容。表面纳米织构以其优异的光电特性,将在未来高效光伏器件中得到重要应用。     

太阳能电池中晶体硅绒面的制作研究

重点是研究不同腐蚀条件对晶体硅片表面织构形貌的影响。通过分析腐蚀条件对表面微结构均匀性的影响,用金相显微镜观察绒面的表面织构形貌,对结果进行分析讨论,确定合理的工艺条件,为实际生产过程中制作良好绒面提供一种最佳工艺条件的参数范围。