Thermoelectric Properties of n-Mg2(SiGe)0.8Sn0.2 Solid Solution

Semiconductors - High values of the thermoelectric figure of merit (ZT = 1.5) in Mg2Si–Mg2Sn solid solutions are caused by a low thermal conductivity and a complex band structure, which is...     

Piecewise parabolic negative magnetoresistance of two-dimensional electron gas with triangular antidot lattice

Extraordinary piecewise parabolic behavior of the magnetoresistance has been experimentally detected in the two-dimensional electron gas with a dense triangular lattice of antidots, where commensurability magnetoresistance oscillations are suppressed. The magnetic field range of 0–0.6 T can be divided into three wide regions, in each of which the magnetoresistance is described by parabolic dependences with high accuracy (comparable to the experimental accuracy) and the transition regions between adjacent regions are much narrower than the regions themselves. In the region corresponding to the weakest magnetic fields, the parabolic behavior becomes almost linear. The observed behavior is reproducible as the electron gas density changes, which results in a change in the resistance by more than an order of magnitude. Possible physical mechanisms responsible for the observed behavior, including so-called “memory effects,” are discussed.     

GaAs–AlGaAs heterostructure thyristors with completely optical transfer of emitter current

Several variants of thyristors based on GaAs-AlGaAs heterostructures with optical transfer of the emitter current are considered. The possibility that thyristors with fully optical transfer of the emitter current can be, in principle, created is demonstrated by means of the results of a study of n-p-n and p-n-p optoelectronic transistors in which the emitter current is converted into light, this light, in turn, being converted into a collector current. Structures of optoelectronic switches of this kind are presented. A switch comprising three constituent transistors has been suggested and fabricated taking into account specific features of the technique for growth of undoped GaAs layers and fabrication of high-voltage p ⁰-n ⁰ junctions with back-ground impurities from these layers, which makes the turn-on delay cardinally shorter and raises the working frequency.     

AC-PDP发光物理过程及影响发光效率、亮度因素的探讨

分析了彩电ＡＣ－ＰＤＰ平面显示结构原理,着重讨论了其物理发光过程,并提出进一步提高ＡＣ－ＰＤＰ发光效率和亮度的途径。     

Delay-dependent fault detection for switched linear systems with time-varying delays—the average dwell time approach

In this paper, the fault detection problem is investigated for a class of discrete-time switched linear systems with time-varying delays. The main purpose is to design a fault detection filter such that, for all unknown inputs, control inputs and time delays, the estimation error between the residual and fault is minimized in an exponential way. The fault detection problem is converted into an exponential H_∞ filtering problem. By using a newly constructed Lyapunov functional and the average dwell time scheme, a novel delay-dependent sufficient condition for the solvability of this problem is established in terms of linear matrix inequalities (LMIs). A numerical example is given to demonstrate the effectiveness of the developed theoretical results.     

门诊草药管理的探讨

草药管理是中医院管理中的难题,解决好草药管理是中医院信息建设的前提。     

The impacts of SILC and hot carrier induced drain leakage current on the refresh time in DRAM

This paper reports the temperature dependence of SILC and hot carrier induced drain leakage current, and their impact on the refresh time in Giga-bit level DRAM with practical considerations. SILC has been found to increase as the monitoring and stress temperature increases. Due to the generation of interface states, hot carrier induced pn junction leakage current and band-to-band tunneling current have been found to increase as the monitoring temperature increases.From the simulation results of a refresh circuit for Giga-bit level DRAM, it has been found that the increase of SILC with stress time is a dominant factor in refresh failure below 373K, and the pn junction leakage current will be a dominant factor at the high elevated temperature. It has been also observed that the increase of hot carrier induced drain leakage current can be a cause for the refresh failure.     

我国热点电信业务的开展情况

从全球来看,电信业务市场明显体现出宽带与移动并重的两大特征：宽带特征是描述业务的支撑条件,移动特征则是描述用户的体验与感受.技术进步及竞争升级促使设备和服务的成本与价格不断下降,宽带接入及移动数据业务的普及使以前可能出现过但是并没有普及的服务逐步被用户接受,包括IPTV、VoIP、移动音乐下载业务等.下面对最近一年来我国电信市场上出现的主要热点和焦点业务逐一进行介绍.     

Analysis of dielectric-loaded waveguide

The calculation of eigenvalues including propagation constants and cutoff wavelengths of longitudinal section electric and magnetic modes of different orders (LSE_nm and LSM_nm modes) in homogeneous and inhomogeneous lossless dielectric-slab-loaded rectangular waveguides using a modified variation-iteration method is presented. The initial eigenvalues used in the iteration are selected on the basis of a physical consideration. As shown in numerical examples, this method is very efficient for finding all the eigenvalues of LSE_nm and LSM_nm modes by a given free-space propagation constant calculation and a given lower bound of the cutoff wavelength for the cutoff wavelength calculation. In addition, the importance of the adaptive update factor in preventing the possibility of missing existing eigenvalues is also discussed     

High-speed photodiodes for the mid-infrared spectral region 1.2–2.4 μm based on GaSb/GaInAsSb/GaAlAsSb heterostructures with a transmission band of 2–5 GHz

High-speed p-i-n photodiodes for the spectral range of 1.2–2.4 μm are fabricated for the first time based on a GaAs/GaInAsSb/GaAlAsSb heterostructure with separated sensitive-(50 μm in diameter) and contact mesas, which are connected by a bridge front contact. The use of an unconventional design for the contact mesa with a Si₃N₄ insulating sublayer 0.3 μm thick under the metal contact made it possible to lower both the intrinsic photodiode capacitance and the reverse dark currents. The photodiodes have a low intrinsic capacitance of 3–5 pF at zero bias and 0.8–1.5 pF at a reverse bias of 3.0 V. The photodiode operating speed, which is determined by the time of increasing the photoresponse pulse to a level of 0.1–0.9, is 50–100 ps. The transmission band of the photodiodes reaches 2–5 GHz. The photodiodes are characterized by low reverse dark currents I _d = 200–1500 nA with a reverse bias of U = ?(0.5–3.0) V, a high current monochromatic sensitivity of R _i = 1.10–1.15 A/W, and a detectability of D*(λ_max, 1000, 1) = 0.9 × 10¹¹ W^?1 cm Hz^1/2 at wavelengths of 2.0–2.2 μm.