新型宽温区高热稳定性微波功率SiGe 异质结双极晶体管

宽温区大电流下的热不稳定性严重制约着功率SiGe 异质结双极晶体管 (HBT) 在射频和微波电路中的应用.为改善器件的热不稳定性, 本文利用SILVACO TCAD建立的多指功率SiGe HBT模型, 分析了器件纵向结构中基区Ge组分分布对微波功率SiGe HBT电学特性和热学特性的影响. 研究表明, 对于基区Ge组分为阶梯分布的HBT, 由于Ge组分缓变引入了少子加速电场, 使它与均匀基区Ge组分HBT相比, 具有更高的特征频率f_T, 且电流增益β和f_T随温度变化变弱, 这有利于防止器件在宽温区工作时电学特性的漂移.同时, 器件整体温度有所降低, 但器件各指温度分布均匀性较差.考虑多指HBT各发射极指散热能力存在差异, 在器件纵向结构设计为基区Ge组分阶梯分布的同时, 对其横向版图进行发射极指间距渐变结构设计, 用于改善器件各指温度分布的均匀性, 进而提高HBT的热稳定性.结果表明, 与基区Ge组分为均匀分布的等发射极指间距结构HBT相比, 新器件各指温度分布均匀性明显改善, f_T保持了较高的值, 且β和f_T 随温度变化不敏感, 热不稳定性得到显著改善, 显示了新器件在宽温区大电流下工作的优越性. 关键词： SiGe 异质结双极晶体管 Ge组分分布 发射极指间距渐变技术 热稳定性     

（FeCp2）0．65FNi（C3S7）2]的合成及表征

合成了一种新型的导电配位型化合物（FeCp2）0．65FNi（C3S7）2].通过元素分析（EA），电感耦合等离子体原子发射光谱（ICP—AES），核磁共振（^1HNMR），紫外光谱（UV）对该化合物进行了表征。     

Building 2D classification models and 3D CoMSIA models on small-molecule inhibitors of both wild-type and T790M/L858R double-mutant EGFR

Molecular Diversity - Epidermal growth factor receptor (EGFR) has received widespread attention because it is an important target for anticancer drug design. Mutations in the EGFR, especially the...     

A wide dynamic range laser rangefinder with cm-level resolution based on AGC amplifier structure

A pulsed time-of-flight (TOF) laser rangefinder with a pulsed laser diode and an avalanche photo diode (APD) receiver is constructed and tested. Trigged by an avalanche transistor, the laser diode can emit a periodic pulse with rise time of ～2 ns. A new structure with auto gain control (AGC) circuits both in the pre-amplifier and the post-amplifier is presented. Through this technology, not only the dynamic range of the receiver is extended, but also the walk error of timing discriminators is reduced. Large measurement range from 5 m to 500 m is achieved without any cooperative target. The single-shot precision is 3 cm for the weakest signal. Compared with previous laser rangefinders, the complexity of this system is greatly simplified.     

Dissociative and molecular oxygen chemisorption channels on reduced rutile TiO2(110): An STM and TPD study

High-resolution scanning tunneling microscopy (STM) and temperature-programmed desorption (TPD) were used to study the interaction of O₂ with reduced TiO₂(110)–(1 × 1) crystals. STM is the technique of choice to unravel the relation between vacancy and non-vacancy assisted O₂ dissociation channels as a function of temperature. It is revealed that the vacancy-assisted, first O₂ dissociation channel is preferred at low temperature (~ 120 K), whereas the non-vacancy assisted, second O₂ dissociation channel operates at temperatures higher than 150 K–180 K. Based on the STM results on the two dissociative O₂ interaction channels and the TPD data, a new comprehensive model of the O₂ chemisorption on reduced TiO₂(110) is proposed. The model explains the relations between the two dissociative and the molecular O₂ interaction channels. The experimental data are interpreted by considering the available charge in the near-surface region of reduced TiO₂(110) crystals, the kinetics of the two O₂ dissociation channels as well as the kinetics of the diffusion and reaction of Ti interstitials.     

狭缝的演变与彩虹全息术的发展

彩虹全息术的发生与发展是与狭缝的引入与演变相关的。本文试图用一个简明的表格形式把迄今为止存在着的各种彩虹全息图及其变化状态做一个形象化的小结。     

Improved DOSY NMR data processing by data enhancement and combination of multivariate curve resolution with non-linear least square fitting

The quality of DOSY NMR data can be improved by careful pre-processing techniques. Baseline drift, peak shift, and phase shift commonly exist in real-world DOSY NMR data. These phenomena seriously hinder the data analysis and should be removed as much as possible. In this paper, a series of preprocessing operations are proposed so that the subsequent multivariate curve resolution can yield optimal results. First, the baseline is corrected according to a method by Golotvin and Williams. Next, frequency and phase shift are removed by a new combination of reference deconvolution (FIDDLE), and a method presented by Witjes et al. that can correct several spectra simultaneously. The corrected data are analysed by the combination of multivariate curve resolution with non-linear least square regression (MCR-NLR). The MCR-NLR method turns out to be more robust and leads to better resolution of the pure components than classic MCR.     

Controlled functionalization of gold nanoparticles through a solid phase synthesis approach

A novel solid phase synthetic strategy was developed in this work for controlled functionalization of gold nanoparticles.