箭叶淫羊藿叶醇提物对自由基的清除作用

采用连苯三酚法产生氧自由基 (O～2 · ) ,采用水杨酸法产生羟自由基 (·OH) ,用分光光度法检测箭叶淫羊藿叶醇提物对O～2 ·和·OH的作用 .结果表明 ,箭叶淫羊藿叶醇提物有清除自由基的作用 .其对氧自由基的清除作用随浓度的增大而增强 ;对羟自由基的清除作用则受浓度的限制 ,浓度低于 0 .3mg·mL-1时 ,对羟自由基有显著的清除作用 ;超过这个浓度时 ,醇提物对羟自由基清除能力显著下降 ,浓度增加到 0 .5mg·mL-1时 ,醇提物对羟自由基不但没有清除作用 ,反而有促进作用     

Al2O3 绝缘栅SiC MIS 结构基本特性的研究

采用原子层淀积(ALD)方法在4H-SiC(0001)8°N-/N+外延层上制备了超薄(~4 nm)Al₂O₃ 绝缘栅高介电常数SiC MIS 电容. 通过对Al₂O₃ 介质膜以及Al₂O₃/SiC 界面微结构和电学特性 分析表明, 实验所得Al₂O₃ 介质膜具有较好的体特性和界面特性, Al₂O₃ 薄膜的击穿电场为25 MV/cm, 并且在可以接受的界面态密度(2×10¹³ cm^-2)下具有较小的栅泄漏电流(8 MV/cm 电场 下漏电流密度为1×10^-3 A/cm^-2). 电流-电压测试分析表明, 在FN 隧穿条件下, SiC/Al₂O₃ 之间的 势垒高度为1.4 eV, 已达到制作SiC MISFET 器件的要求. 同时, 在整个栅压区域也受 Frenkel-Poole 和Schottky 机制的共同影响.     

Negative differential resistance in single-walled SiC nanotubes

A two-probe system was established for a finite （7, 0） silicon carbide （SIC） nanotube coupled to Au （111） surfaces via Au-C bonds. Using the non-equilibrium Green function （NEGF） combined with density functional theory （DFT）, the above system was studied for its electronic transport properties. Negative differential resistance （NDR） was observed when the bias voltage was greater than 1.4 V. Because the transport properties of the system were sensitive to the applied bias voltage, NDR might be caused by the fluctuation of the transmission coefficient with the bias voltage.     

Analysis of temperature-dependent characteristics of a 4H-SiC metal-semiconductor-metal ultraviolet photodetector

We investigate the temperature dependence of current-voltage and spectral response characteristics of a 4H-SiC metal-semicon-ductor-metal (MSM) ultraviolet photodetector in the temperature range from room temperature to 800 K with two-dimensional (2D) numerical simulator ISE-DESSIS. It is found that the dark current and photocurrent increase with the increasing temperature. For the range of 500-800 K, the dark current increases by nearly a factor 3.5 every 150 K larger than that of photocurrent, leading to a negative effect on photodetector current ratio (PDCR). Nevertheless, the PDCR is still greater than 200 even at 800 K, which exhibits the excellent thermal stability. In addition, the responsivity has an unsymmetrical trend. As temperature rises, it is clear that a remarkable red-shift of 12 nm occurs and overall responsivity is enhanced for longer wavelength. While the short-wave-length response remains relatively independent of temperature. The mechanism of indirect and direct band absorption transition is responsible for temperature-dependent spectrum distribution. These findings provide a significant insight on the design of the MSM detector operated at elevated temperature.     

Effect of dummy vias on interconnect temperature variation

The number of the dummy via can significantly affect the interconnect average temperature.This paper explores the modeling of the interconnect average temperature in the presence of multiple dummy vias.The proposed model incorporates the multi-via effect into the effective thermal conductivity of the interlayer dielectric (ILD) to obtain accurate results.Using different ILDs,the multi-via effect is analyzed and discussed.Also,the extended applications of the multi-via effect are presented in this paper to obtain the minimum interconnect average temperature increase with a given via separation or number.This study suggests that the multi-via effect should be accounted for in integrated circuits design to optimize the performance and design accuracy of integrated circuits.