饱和吸附H原子的Si（100）表面的光学二次谐波研究

测量了Ｓｉ（１００）（２×１）－Ｈ表面和Ｓｉ（１００）（３×１）－Ｈ表面的反射二次谐波强度随温度的变化关系，并与清洁的Ｓｉ（１００）（２×１）表面进行了比较。Ｓｉ（１００）（２×１）表面和Ｓｉ（１００）（３×１）－Ｈ表面的二次谐波强度随温度的上升而单调地减小，Ｓｉ（１００）（２×１）－Ｈ表面二次谐波强度随温度的变化不是单调的，约在４７０Ｋ时信号最大。可以根据二次谐波信号的强度及其随温度的变化关系来确定样品温度和表面结构。     

2，5─哌嗪二酮与α，β─不饱和醛反应研究

综合运用了多种波谱学方法及化学手段确证并归属了２，５－哌嗪二酮与α，β－不饱和醛在超声波分散金属钾及双季铵盐作用下反应产物的立体化学与核磁共振信号，为研究这个反应提供了有用的信息．     

用偶幂级数处理Abel变换问题

本文提出了用偶幂级数代替对称分布函数,使其线积分成为递推可积,从而简化了Abel逆变换。引进权函数使本方法简单地过渡到非对称问题。对一组假想相移信号进行变换,获得了可靠的密度分布结果,并对影响变换精度的各种因素作了讨论。     

一个简洁的最小二乘法拟合程序

一个简洁的最小二乘法拟合程序陈乃强（河北师范学院物理系石家庄０５００９１）用最小二乘法对含有随机误差的离散数据进行曲线拟合，能将变量ｘ与ｙ间变化关系的ｍ对测量值，总结成ｘ、ｙ间最可几的函数表达式ｙ＝ｆ（ｘ）．但由于此方法所需计算量甚大，故只有在微机已...     

金属表面在反射方向产生光学二次谐波的研究(Ⅰ)

用Rudnick和Stern引入的唯象参数“a”和“b”来描述表面电流,本文推导了金属表面在反射方向产生的光学二次谐波的表达式.由此证明了:从谐波信号随入射光偏振态的变化可以直接得到关于参数“a”的信息.和过去的实验相比,这种方法能更加精确、可靠地测定“a”的数值.     

平面上方二维介质目标对高斯波束的电磁散射研究

基于矩量法、互易性定理及镜像理论,提出了一种新的混合方法用于研究水平分界面上方二维介质目标对垂直入射高斯波束的差值散射场.应用镜像理论,介质水平分界面可被原始目标相对于该分界面的镜像目标所替代,从而给出散射问题的等效模型.在等效模型中,应用矩量法求解了原始目标及镜像目标对高斯波束的散射场,同时结合互易性定理得到了原目标与其镜像目标之间的耦合散射场.数值计算结果与相关文献方法及MoM所得结果进行了比较,验证了该混合方法的有效性. 关键词： 互易性定理 电磁散射 高斯波束 二维目标     

A two-dimensional analytical model for channel potential and threshold voltage of short channel dual material gate lightly doped drain MOSFET

An analytical model for the channel potential and the threshold voltage of the short channel dual-material-gate lightly doped drain （DMG-LDD） metal-oxide-semiconductor field-effect transistor （MOSFET） is presented using the parabolic approximation method. The proposed model takes into account the effects of the LDD region length, the LDD region doping, the lengths of the gate materials and their respective work functions, along with all the major geometrical parameters of the MOSFET. The impact of the LDD region length, the LDD region doping, and the channel length on the channel potential is studied in detail. Furthermore, the threshold voltage of the device is calculated using the minimum middle channel potential, and the result obtained is compared with the DMG MOSFET threshold voltage to show the improvement in the threshold voltage roll-off. It is shown that the DMG-LDD MOSFET structure alleviates the problem of short channel effects （SCEs） and the drain induced barrier lowering （DIBL） more efficiently. The proposed model is verified by comparing the theoretical results with the simulated data obtained by using the commercially available ATLASTM 2D device simulator.     

Influence of the channel electric field distribution on the polarization Coulomb field scattering in In0.18Al0.82N/AIN/GaN heterostructure field-effect transistors

By making use of the quasi-two-dimensional （quasi-2D） model, the current-voltage （l-V） characteristics of In0AsA10.82N/A1N/GaN heterostructure field-effect transistors （HFETs） with different gate lengths are simulated based on the measured capacitance-voltage （C-V） characteristics and I-V characteristics. By analyzing the variation of the electron mobility for the two-dimensional electron gas （2DEG） with electric field, it is found that the different polarization charge distributions generated by the different channel electric field distributions can result in different polarization Coulomb field scatterings. The difference between the electron mobilities primarily caused by the polarization Coulomb field scatterings can reach up to 1522.9 cm2/V.s for the prepared In0.38AI0.82N/A1N/GaN HFETs. In addition, when the 2DEG sheet density is modulated by the drain-source bias, the electron mobility presents a peak with the variation of the 2DEG sheet density, the gate length is smaller, and the 2DEG sheet density corresponding to the peak point is higher.     

一种新型高透射率高品质因子光子晶体耦合腔波导结构

提出了一种在二维三角晶格光子晶体线缺陷波导中放置椭圆空气孔的耦合腔波导结构。基于平面波展开法,利用MPB对线缺陷波导的能带结构进行了计算并给出能带图。基于时域有限差分法（FDTD）,利用MEEP对椭圆空气孔在波导中的排列方式、数量、尺寸进行优化设计,并对频率位于微腔共振频率处的光波在耦合腔波导结构中的品质因子和传输特性进行研究与比较,给出了电场分布图。仿真结果表明,当椭圆空气孔的长轴方向纵向排列时,相应的微腔共振频率在光子禁带内可获得90%以上的透射率,对应的品质因子Q可达10⁴量级;选择合适的参数,获得的Q可高达10⁷量级,对应共振频率的透射率仍在60%以上。