一种脉冲编码CMOS神经元电路的设计与实现

从生物神经元的电化学特性出发,基于积分发放(I&F)电路理论模型,提出了一种新型的结构紧凑的脉冲编码CMOS神经元电路,模仿神经元细胞体输出连续脉冲串.该模型的优点在于大大简化了模型结构,其运行结果很好地拟合了神经元的生理特性,且在工艺参数不可调节的情况下,可通过输入信号灵活控制电路结构,改变输入耦合权重,从而实现对输...     

High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre

A high efficiency and broad bandwidth grating coupler between a silicon-on-insulator (SOI) nanophotonic waveguide and fibre is designed and fabricated. Coupling efficiencies of 46\% and 25\% at a wavelength of 1.55~μ m are achieved by simulation and experiment, respectively. An optical 3~dB bandwidth of 45~nm from 1530~nm to 1575~nm is also obtained in experiment. Numerical calculation shows that a tolerance to fabrication error of 10~nm in etch depth is achievable. The measurement results indicate that the alignment error of ±2~μ m results in less than 1~dB additional coupling loss.     

Influence of dopant concentration on electrical quantum transport behaviors in junctionless nanowire transistors

We discuss the random dopant effects in long channel junctionless transistor associated with quantum confinement effects. The electrical measurement reveals the threshold voltage variability induced by the random dopant fluctuation.Quantum transport features in Hubbard systems are observed in heavily phosphorus-doped channel. We investigate the single electron transfer via donor-induced quantum dots in junctionless nanowire transistors with heavily phosphorusdoped channel, due to the formation of impurity Hubbard bands. While in the lightly doped devices, one-dimensional quantum transport is only observed at low temperature. In this sense, phonon-assisted resonant-tunneling is suppressed due to misaligned levels formed in a few isolated quantum dots at cryogenic temperature. We observe the Anderson-Mott transition from isolate electron state to impurity bands as the doping concentration is increased.     

Electronic transport properties of silicon junctionless nanowire transistors fabricated by femtosecond laser direct writing

Silicon junctionless nanowire transistor(JNT) is fabricated by femtosecond laser direct writing on a heavily n-doped SOI substrate.The performances of the transistor,i.e.,current drive,threshold voltage,subthreshold swing(SS),and electron mobility are evaluated.The device shows good gate control ability and low-temperature instability in a temperature range from 10 K to 300 K.The drain currents increasing by steps with the gate voltage are clearly observed from 10 K to50 K,which is attributed to the electron transport through one-dimensional(1D) subbands formed in the nanowire.Besides,the device exhibits a better low-field electron mobility of 290 cm~2·V~(-1)·s~(-1),implying that the silicon nanowires fabricated by femtosecond laser have good electrical properties.This approach provides a potential application for nanoscale device patterning.     

直接键合硅片界面键合能的理论分析

直接键合硅片界面的键合能依赖于界面成键的密度,是退火温度和时间的函数,界面反应激活能决定着成键的行为．硅片键合能随退火温度分两步增加,这种现象被归因于界面反应存在两种不同的激活能．将硅本征氧化层与硅热氧化层两种键合界面在退火过程中的行为进行了理论分析与比较．硅本征氧化层的键合能随温度的增加要比热氧化层界面的大．键合能的饱和时间与激活能密切相关．     

智能剥离工艺的热动力学模型(英文)

提出了注氢硅片表面借助键合氧化硅片进行剥离的热动力学模型 ,这种剥离现象是退火过程中氢离子注入区氢气泡横向增长的结果 .氢气泡的增长速率依赖于氢复合体分解和氢分子扩散所需的激活能 ,氢气泡的半径是退火时间、退火温度和注氢剂量的函数 .氢气泡的临界半径可根据 Griffith能量平衡条件来获得 .根据氢气泡增长的这一临界条件 ,获得了不同劈裂温度时所需的剥离时间     

一种有效的邻近效应修正方法

本文介绍了在电子束光刻中修正邻近效应的一种有效的剂量补偿方法。在其它曝光参数一定的条件下（包括加速电压,抗蚀剂厚度,曝光步长大小及衬底材料等）图形尺寸由剂量大小决定。本方法基于两种合理的假设来确定补偿剂量因子。一是假设在特定实验范围内,剂量的大小和圆直径的关系可以看作是线性的。二是假设补偿剂量因子仅受最近邻图形的影响。四层六角光子晶体作为本实验方法的测试图形。比较没有修正的结构,修正后的结构中孔大小的一致性得到了显著的提高     

高质量二维光子晶体结构刻蚀掩膜版的制作方法

结合制作光子晶体结构的具体要求,研究了电子束曝光得到的电子束胶上(GaAs衬底)随实验条件变化的图形.结果表明,胶的厚度、曝光剂量、显影/定影时间等参数对图形的质量有重要影响.通过合理优化这些参数,我们得到了高质量的掩膜图形.     

Design, fabrication and characterization of a high-performance microring resonator in silicon-on-insulator

A high-performance microring resonator in a silicon-on-insulator rib waveguide is realized by using the electron beam lithography followed by inductively coupled plasma etching. The design and the experimental realization of this device are presented in detail. In addition to improving relevant processes to minimize propagation loss, the coupling efficiency between the ring and the bus is carefully chosen to approach a critical coupling for high performance operating. We have measured a quality factor of 21,200 and an extinction ratio of 12.SdB at a resonant wavelength of 1549.32nm. Meanwhile, a low propagation loss of 0.89dB/mm in a curved waveguide with a bending radius of 40μm is demonstrated as well.     

直接键合硅片界面键合能的理论分析

直接键合硅片界面的键合能依赖于界面成键的密度 ,是退火温度和时间的函数 ,界面反应激活能决定着成键的行为 .硅片键合能随退火温度分两步增加 ,这种现象被归因于界面反应存在两种不同的激活能 .将硅本征氧化层与硅热氧化层两种键合界面在退火过程中的行为进行了理论分析与比较 .硅本征氧化层的键合能随温度的增加要比热氧化层界面的大 .键合能的饱和时间与激活能密切相关