半绝缘SiC单晶电阻率均匀性研究

采用非接触电阻率面分布(COREMA)方法对本实验室生长得到的2英寸(50 mm)4H和6H晶型半绝缘SiC单晶片进行电阻率测试,结果发现数据的离散性大,低者低于测试系统下限105Ω.cm,高者高于其上限1012Ω.cm,甚至在同一晶片内会出现小于105Ω.cm,105~1012Ω.cm和大于1012Ω.cm的不同区域,而有的晶片则电阻率的均匀性较好。将SiC电阻率测试结果与二次离子质谱(SIMS)对晶体内主要杂质V,B和N含量测试结果相结合,初步探讨得到引起掺钒SiC单晶电阻率的高低及均匀性的变化由补偿方式决定,在深受主补偿浅施主模式下,V的浓度控制在2×1016~3×1017cm-3,N的浓度控制在1×1016cm-3左右,深受主钒充分补偿浅施主氮,制备得到的SiC单晶具有半绝缘性,且电阻率均匀性好。     

Invariant pseudometrics on Palais proper G-spaces

Let G be a locally compact Hausdorff group. It is proved that: 1. on each Palais proper G-space X there exists a compatible family of G-invariant pseudometrics; 2.the existence of a compatible G-invariant metric on a metrizable proper G-space X is equivalent to the paracompactness of the orbit space X/G; 3. if in addition G is either almost connected or separable, and X is locally separable, then there exists a compatible G-invariant metric on X. This revised version was published online in June 2006 with corrections to the Cover Date.     

Determination of swing curve “shifts” as a function of illumination conditions: Impact on the CD uniformity

The use of a wide range of optical illumination settings may generate significant shifts in the photoresist (PR) swing curves. For technologies where critical dimension controls of few nanometers are required, the impact of these shifts on the critical dimension uniformity must be taken into account. In this paper, we have reproduced and quantified the shift of different swing curves (dose-to-clear and critical dimension) with a 248 nm positive PR. The impact of such shift on critical dimension uniformity has been determined on Deep UV Scanner.     

微波炉功率,均匀性及安全性的测定

本文用国际电工委员会(IEC)建议的方法对市场上几种常见类型家用微波炉的输出功率、均匀性及安全性进行了更仔细的测定.由我们的工作得出结论:测量微波炉功率时,用2000g水作为负载较为合适,且负载面积应占腔体底面积的16%以上,此时测出的功率更准确和接近标称功率,而测定微波炉漏能时则应使用较小负载.转盘转动时负载的受热均匀性较转盘静止时提高约1倍.     

用偏振和有规位相分布抑制线聚焦系统的小尺度不均匀性

研究了一种用以抑制光楔列线聚焦系统在靶面产生的干涉尖端的方法。由这种尖峰引起的小尺度不均匀性对Ｘ射线激光的产生是不利的。利用特殊分布的偏振态和位相，可把尖峰引向更密度伯程度，而且其对比度下降，这将有利于它通过靶物质自身的横向热传导而平滑化。对于四单元的列阵系统，甚至可将尖峰完全消除。     

基于非球面镜的激光能量均匀化设计

针对激光光束的能量均匀化研究，先后出现了多种方法，基于“不等步长采样”原理设计了包含非球面镜的光学系统。首先从理论上分析了其可行性，然后对实际激光光束进行了能量均匀化的设计。模拟分析结果表明，出射光束发散度小于0．02°，照度均匀度达92．9％，证明了此方法的可行性。     

The depth invariant for group actions on countable phase spaces

The construction of the depth of a countable symbolic system, which was studied earlier by the author for actions of the group , is generalized to the case of an arbitrary finitely generated Abelian group action. A new property, which is called the uniformity of the depth, is studied. The depth, which takes values in the set of at most countable ordinals, is a topological invariant of countable symbolic systems. In the paper we describe the set of possible values of the depth invariant and the method of constructing dynamical systems with an arbitrary admissible depth. Translated fromMatematicheskie Zametki, Vol. 65, No. 6, pp. 893–907, June, 1999.     

A comparative study of the synthetic paths from 1-butyne to 2E,4Z-heptadien-1-ol

2E,4Z-Heptadien-1-ol (1), the key intermediate in the synthesis of the grapevine moth sex pheromone, was obtained from 1-butyne by a number of alternative procedures, including various variants of the stereocontrolled building of the conjugatedE,Z-diene system (Cadiot—Chodkiewicz cross-coupling, alkyne—vinyl halide cross-coupling catalyzed by palladium complexes, anionotropic allylic rearrangement, partialcis- andtrans-reduction of the triple bond). None of them could provide for configurational uniformity of1. The most acceptable path to obtain1 in multigram amounts appears to be that which proceeds via the conjugated diynol and enynol intermediates with subsequent catalyticcis-hydrogenation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 769–772, April, 1993.     

Effect of power modulation on radical concentration and uniformity in a single-wafer plasma reactor

The effect of power modulation oil radical concentration and uniformity in a single-wafer plasma reactor was investigated with a radical transport and reaction model. Plasma etching of silicon using tetrafluoromethane under relatively high pressure (l torr) high frequency (13.56 MHz) conditions was taken as an example system. Gas velocity, temperature, and radical concentration profiles were obtained numerically by a finite element method. When compared to a contin uous wave plasma, power modulation can alter the relative concentration of radicals and in turn the each rate and uniformity as well as selectivity and anisotropy Uniformity is improved by power modulation except at high flow rates which, however, result in poor utilization of the feedstock gas.     

像增强器的荧光屏亮度均匀性测试的校正法研究

像增强器荧光屏亮度均匀性参数是判断其性能好坏的一个重要技术指标。设计了一种测试系统来测试它的亮度均匀性参数。该系统利用标定过的具有均匀亮度的荧光屏(裸屏),以标准像增强器的图像作为标准来校正面源电子枪。由于校正后的面源电子枪仍然存在误差,所以具有均匀亮度的荧光屏(裸屏)的图像不可能是完全均匀的,呈现边缘暗中间亮。分析其图像的亮度曲线,建立校正函数,改变校正函数中的调节系数,直到计算机上显示出图像均匀为止,这时可得出系数确定的校正函数。首先利用校正后的电子枪轰击待测荧光屏,采集其图像,以确定的校正函数对其进行修正,然后观察由计算机显示出的图像是否均匀,从而判断待测荧光屏的均匀性。