Thin film transmission matrix approach to fourier transform infrared analysis of HgCdTe multilayer heterostructures

The ability to achieve high-yield focal plane arrays from Hg_1−xCd_xTe molecular beam epitaxy material depends strongly on postgrowth wafer analysis. Nondestructive analysis that can determine layer thicknesses as well as alloy compositions is critical in providing run-to-run consistency. In this paper, we incorporate the use of a thin film transmission matrix model to analyze Fourier transform infrared (FTIR) transmission spectra. Our model uses a genetic algorithm along with a multidimensional, nonlinear minimization Nelder-Mead algorithm to determine the composition and thickness of each layer in the measured epitaxial structure. Once a solution has been found, the software is able to predict detector performance such as quantum efficiency and spectral response. We have verified our model by comparing detector spectral data to our predicted spectral data derived from the room-temperature FTIR transmission data. Furthermore, the model can be used to generate design curves for detectors with varying absorber thicknesses and/or different operating temperatures. The consequence of this are reduced cycle times and reduced design variations.     

基于PIC16C72的空调遥控操作的实现

介绍了一种基于单片机的民用经济型遥控挂壁式空调遥控操作的实现,给出了遥控接收电路及遥控数据中逻辑电平0和1的表示方法,定制了有效的数据传输协议,最后给出了遥控接收,处理程序流程图.     

Formation of 10-30 nm SiO2/Si structure with a uniform thickness at ∼120 °C by nitric acid oxidation method

Silicon dioxide (SiO₂) layers with a thickness more than 10 nm can be formed at ∼120 °C by direct Si oxidation with nitric acid (HNO₃). Si is initially immersed in 40 wt.% HNO₃ at the boiling temperature of 108 °C, which forms a ∼1 nm SiO₂ layer, and the immersion is continued after reaching the azeotropic point (i.e., 68 wt.% HNO₃ at 121 °C), resulting in an increase in the SiO₂ thickness. The nitric acid oxidation rates are the same for (1 1 1) and (1 0 0) orientations, and n-type and p-type Si wafers. The oxidation rate is constant at least up to 15 nm SiO₂ thickness (i.e., 1.5 nm/h for single crystalline Si and 3.4 nm/h for polycrystalline Si (poly-Si)), indicating that the interfacial reaction is the rate-determining step. SiO₂ layers with a uniform thickness are formed even on a rough surface of poly-Si thin film.     

微波斜径传播对流层大气湍流结构常数模型

在微波遥感和卫星通信领域内，对流层湍流大气引起的信号闪烁现象的研究是至关重要的一个问题。引起接收信号闪烁的大气折射率起伏一般由大气结构常数(Cn^2来度量。根据ITU—R光波波段的Cn^2模型及ITU—R幅度闪烁标准偏差σχ的经验模型讨论了在微波波段影响Cn^2的主要因素；建立了微波波段的Cn^2模型。其优点是考虑了大气温度和湿度随高度的变化。根据湍流的幅度闪烁理论，在频率分别为12GHz，20GHz和30GHz时，用该Cn^2模型计算了σχ，并与ITU—R和Ortgies模型的预测结果进行了比较，结果表明一致性较好，说明该Cn^2模型是实用的。     

Change in the optical properties of paper when exposed to the magnetic component of a high-frequency electromagnetic field

We have used laser Stokes polarimetry to study changes in the structure of paper for offset printing when exposed to a high-frequency electromagnetic field. We have shown that the effect of a high-frequency electromagnetic field on paper appears as a decrease in the structural ordering of the material and a change in the shape of the indicatrix of the reflected radiation power from an He-Ne laser at the wavelength 632.8 nm, a decrease in the bidirectional reflection and transmission coefficients of the paper. We have established that when the force lines of the magnetic component of the high-frequency electromagnetic field are oriented perpendicular to the plane of the sheet of paper, we observe a more substantial decrease in the anisotropy in the surface layer and within the interior (the volume) of the paper than when the lines of force are oriented parallel to the plane of the paper. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 421–426, July–August, 2007.     

高对比度滤光片的研制

本文介绍自行研制的高对比度滤光片。它具有较低的表面光反射率、选择性透过率和电磁屏蔽特性。     

SRS效应在双向波分复用系统中的单向等效

对在双向传输波分复用情况下系统中的受激喇曼散射（SRS）效应进行了研究。对在不含放大器以及包含级联EDFA等情况下受激喇曼散射对双向系统的影响进行了理论及模拟分析，通过对照单向系统的对应性能，发现双向系统中的SRS效应的端特性可以通过一个对应的单向系统进行等效，从而使我们可以以较少的工作量对双向系统进行细致、准确、简洁的分析。     

Exact solution of sound reflection on infinite laminated plate and transmission through it

An exact solution is proposed in this paper based on the elasticity theory for sound reflection from an infinite laminated plate and transmission through it, and some phenomena of sound propagation in an isotropic media are also discussed. Some examples given here could be used to test approximate models of laminated plates.     

Land mobile satellite communication channel model for simultaneous transmission from A land mobile terminal via two separate satellites

There are certain data services that could use transmit-only land-mobile satellite communication terminals. Such terminals would not be able to receive acknowledged messages and transmit them onward. Thus it is of interest to study alternative means of improving the system reliability. In this paper we propose the use of transmission to two satellites separated in azimuth and elevation in order to improve the reliability of throughput. We have investigated the improvements by building upon the model proposed by Lutz for land mobile satellite communications via one satellite, and extended this using measurements of the shadowing coefficient in different areas (suburban, countryside and city) to two separated satellites. The measured data is used to produce an empirical model of the equivalent shadowing coefficient variations with the separation angle variation between two satellites. The results show good agreement with the shadowing coefficients produced by the Lutz model for a single satellite. The degree of improvement produced by using two separated satellites in the different environments, in terms of bit rate and probability of the received power is given.     

InSb/GaAs半导体界面结构研究

本文通过对ＩｎＳｂ／ＧａＡｓ半导体界面实验高分辨原子像的计算机定量分析得到了界面位错区附近的晶格点畸变位移分布，基于该实验结果中文提出了ＩｎＳｂ／ＧａＡｓ半导体界面的结构互平衡界面结构模型，该界面模型合理地解释了界面位错的起因及ＩｎＳｂ薄膜在ＧａＡｓ基体上升延生长过程中的物理现象，计算机模拟的界面电子衍射谱和高分辨原子像与实验结果的一致性符合验证的所建立的界面模型的正确性。