Generalized threshold chase algorithms

 Three generalized threshold Chase algorithms called GTC Ⅰ,GTC Ⅱ and STC are proposed in this paper.They are the combination of the generalized minimum distance(GMD)decoding algorithm with the Chase algorithm.Although the decoding error probabilities of these algorithms are very close to that of the Chase algorithm,the decoding speeds are faster,especially at higher signal-to-noise ratio(SNR),hence they are of greater practical value.The results of computer simulations are given,showing the advantages of these algorithms.     

The fabrication of vibration energy harvester arrays based on AIN piezoelectric film

Abstract： The fabrication and measurement results of the vibration energy harvester arrays based on the piezoelectric aluminum nitride （AlN） film are presented. The structure design and fabrication process of the device are introduced. The key material, the AIN film with crystal orientation （002）, was deposited by pulsed-DC magnetron sputtering and characterized by X-ray diffraction （XRD）. The resonant frequency, power out, and the open circuit voltage of the device are detected. The optimized load of 80 kΩ and a remarkable maximum power out of 30.4 μW are obtained when the acceleration of 0.9g （g is standard gravity acceleration） is applied. Key words： A1N; crystal orientation; harvester arrays; vibration energy     

Design and Implementation of a Novel HomePlug-Based Solution for Low Cost and High Performance Smart Home Networking

As the smart home is the end-point power consumer, it is the major part to be controlled in a smart micro grid. There are so many challenges for implementing a smart home system in which the most important ones are the cost and simplicity of the implementation method. It is clear that the major share of the total cost is referred to the internal controlling system network; although there are too many methods proposed but still there is not any satisfying method at the consumers’ point of view. In this paper, a novel solution for this demand is proposed, which not only minimizes the implementation cost, but also provides a high level of reliability and simplicity of operation; feasibility, extendibility, and flexibility are other leading properties of the design.     

Stacking fault energy in some single crystals

The stacking fault energy of single crystals has been reported using the peak shift method. Presently studied all single crystals are grown by using a direct vapor transport (DVT) technique in the laboratory. The structural characterizations of these crystals are made by XRD. Considerable variations are shown in deformation (α) and growth (β) probabilities in single crystals due to off-stoichiometry, which possesses the stacking fault in the single crystal.     

Structural and opto-electrical properties of pyrolized ZnO-CdO crystalline thin films

A series of ZnO-CdO thin films of different molar ratios of Zn and Cd have been deposited on glass substrate at substrate temperature ~ 360 ℃ by the spray pyrolysis technique at an ambient atmosphere. X-ray diffraction (XRD) studies confirmed the polycrystalline nature of the film and modulated crystal structures of wurtzite (ZnO) and cubic (CdO) are formed. The evaluated lattice parameters, and crystallite size are consistent with literature. Dislocation density and strain increased in the film as the grain sizes of ZnO and CdO are decreased. The band gap energy varies from 3.20 to 2.21 eV depending on the Zn/Cd ratios in the film. An incident photon intensity dependent I-V study confirmed that the films are highly photosensitive. Current increased with the increase of the intensity of the light beam. The optical conductivity and the optical constants, such as extinction coefficient, refractive index and complex dielectric constants are evaluated from transmittance and reflectance spectra of the films and these parameters are found to be sensitive to photon energy and displayed intermediate optical properties between ZnO and CdO, making it preferable for applications as the buffer and window layers in solar cells.     

Few-mode vertical-cavity surface-emitting lasers for space-division multiplexing

In order to choose the proper radius of oxide aperture for few-mode vertical-cavity surface-emitting lasers (VCSELs), the influences of oxide aperture size on the multi-transverse-mode behaviors are investigated in detail. By establishing the effective refractive index model to simulate VCSELs with different radii of oxide apertures, the wavelength and corresponding order of different modes are obtained. VCSELs with three kinds of oxide apertures are manufactured. Then the multi-transverse-mode spectra and near-field are measured. It is found that when the radius is between 1.5 and 4.5 μm, few-mode VCSELs can be implemented. The 2.5 μm VCSEL manufactured in this paper only emits LP01 mode and LP21 mode. Since the space distance between the two modes is 2 μm, it is expected to realize direct-modulation few-mode VCSELs by channel etching or ion implantation between the two modes.     

Full Band Monte Carlo Simulation of Electron Transport in Ge with Anisotropic Scattering Process

The electron transport properties in Ge are calculated by full band Monte Carlo technique with anisotropic scattering consideration.The calculation procedures are as follows:the full band structure is calculated by nonlocal empirical pseudopotential approach;the relative value of density of state (DOS) is computed by counting the number of states located in a certain region of the energy;the phonon dispersion curve is obtained from an adiabatic bondcharge model;the electron-phonon scattering rates are approximated by the nonparabolic model derived from Fermi’s golden rule at low energy region and scaled by DOS at higher energy region;the energy and momentum conservations are employed for choosing the final state after scattering.The validity of this Monte Carlo simulator and the physical models that are used is fully confirmed by comparing the program output to experimental results listed in references.As this Monte Carlo model can accurately reproduce the velocity and energy characteristics of electrons in Ge and the DOS scaled scattering rate can significantly reduce the computational cost for scattering rates,this approach is suitable for device simulation.     

量子线结构的高压平衡方程(英文)

<正> Balance equations for steady-state nonlinear electronic transport in the presence of an electric field are established both for a single quasi 1D-heterostructure and for a multiquantum-wire superlattice. The carrier-impurity scatterings, including the background impurities inside the wires and the remote impurities outside the wires, and the carrier-phonon scatterings in the long wavelength limit have been taken into account. The general equations for determining the resistivities are obtained. To discuss the Ohmic mobility formulas,we concentrate on the scatterings at low temperature. The density-density correlation functions in the random phase approximation (RPA) for the wire structures are also studied in some detail.     

Progress in MOVPE of HgCdTe for advanced infrared detectors

This paper reviews the significant progress made over the past five years in the development of metalorganic vapor phase epitaxy (MOVPE) for the in situ growth of HgCdTe p-n junction devices for infrared detector arrays. The two basic approaches for MOVPE growth of HgCdTe, the interdiffused multilayer process (IMP), and direct alloy growth (DAG) are compared. The paper then focuses on the progress achieved with the IMP approach on lattice-matched CdZnTe substrates. The benefits of the precursors ethyl iodide (EI) and tris-dimethylaminoarsenic (DMAAs) for controlled iodine donor doping and arsenic acceptor doping at dopant concentrations relevant for HgCdTe junction devices are summarized along with the electrical and lifetime properties of n-type and p-type HgCdTe films grown with these precursors. The relative merits of the two CdZnTe substrate orientations we have used, the (211)B and the (100) with 4°–8° misorientation are compared, and the reasons why the (211)B is preferred are discussed. The growth and repeatability results, based on secondary ion mass spectrometry analysis, are reported for a series of double-heterojunction p-n-N-P dual-band HgCdTe films for simultaneous detection in the 3–5 μm and 8–10 μm wavelength bands. Finally, the device characteristics of MOVPE-IMP in situ grown p-on-n heterojunction detectors operating in the 8–12 μm band are reviewed and compared with state-of-the-art liquid phase epitaxial grown devices.     

Performance limitation of short wavelength infrared InGaAs and HgCdTe photodiodes

The carrier lifetimes in In_xGa_1−xAs (InGaAs) and Hg_1−xCd_xTe (HgCdTe) ternary alloys for radiative and Auger recombination are calculated for temperature 300K in the short wavelength range 1.5<λ<3.7 μm. Due to photon recycling, an order of magnitude enhancements in the radiative lifetimes over those obtained from the standard van Roosbroeck and Shockley expression, has been assumed. The possible Auger recombination mechanisms (CHCC, CHLH, and CHSH processes) in direct-gap semiconductors are investigated. In both n-type ternary alloys, the carrier lifetimes are similar, and competition between radiative and CHCC processes take place. In p-type materials, the carrier lifetimes are also comparable, however the most effective channels of Auger mechanism are: CHSH process in InGaAs, and CHLH process in HgCdTe. Next, the performance of heterostructure p-on-n photovoltaic devices are considered. Theoretically predicted R_oA values are compared with experimental data reported by other authors. In_0.53Ga_0.47As photodiodes have shown the device performance within a factor often of theoretical limit. However, the performance of InGaAs photodiodes decreases rapidly at intermediate wavelengths due to mismatch-induced defects. HgCdTe photodiodes maintain high performance close to the ultimate limit over a wider range of wavelengths. In this context technology of HgCdTe is considerably advanced since the same lattice parameter of this alloy is the same over wide composition range.