Observations of Neutral Impurity Emission during Operation of Intense Pulsed Ion and Electron Diodes

The number of neutral particles (N) emitted during the pulsed operation of two magnetically insulated ion diodes and a typical electron diode were measured with an ionization technique. Among the factors that were found to affect the total number of emitted neutrals were the elapsed time between consecutive firings and the power of the voltage pulse. A typical value of N for the electron diode operating at approximately 300 kV and 80 kA was 1019, while values of N for the ion diodes operating in the 90-320 kV range were 3-30 times greater.     

激光电源脉冲功率切换电路仿真分析

激光电源脉冲功率切换电路稳定工作是电源可靠性的保证。电路参数选取直接影响晶闸管、二极管的工况,而晶闸管的良好工况是保证切换激光电源长期可靠运行的基本条件。基于PSCAD软件建立切换电路的仿真模型,重点仿真分析了阻容电路参数配置、限流电阻、并联晶闸管触发同步性对晶闸管和二极管的影响。仿真结果表明,电流上升率过大是晶闸管门极损坏的原因,关断支路中的反向过压是二极管损坏的原因。并针对实际电路,提出晶闸管二极管保护的优化配置方案。     

Experimental Investigation of the Spectrum Characteristics of Laser Diodes Under Low Frequency Modulation

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Effect of prolonged operation and temperature on the spectra of silicon carbide lightemitting diodes operating in an electric breakdown regime

The effect of prolonged operation and temperature on the spectral distribution of the quantum yield of silicon carbide light-emitting diodes operating in an electric breakdown regime is investigated. The spectrum of the light-emitting diodes is found to change in a regular manner during prolonged operation. It is found that self-absorption and the temperature shift of the bands have a large effect on the spectral distribution of the temperature coefficient of emission. The conditions for obtaining the most stable light-emitting diodes possible, which can be used as standard visible-range emitters, are determined. Zh. Tekh. Fiz. 69, 69–76 (October 1999)     

Quasi-three-level Nd:YAG laser under diode pumping directly into the emitting level

We present theoretical and experimental investigations on ground-state direct pumping at 869 nm into the emitting level ⁴F_3/2 of end-pumped quasi-three-level Nd:YAG lasers operating at 946 nm. We have demonstrated, what we believe is for the first time, a Nd:YAG laser at 946 nm directly pumped by diodes and obtained 1.6 W of output power.     

Coherent summation of power of nanosecond relativistic microwave oscillators

The possibility of developing a two-channel nanosecond relativistic microwave oscillator with a phase stability in each channel sufficient for coherent summation of their electromagnetic fields is demonstrated experimentally. In experiments, vacuum diodes of two independent superradiant backward wave oscillators operating in 10-GHz frequency range were connected to a common voltage source with a subnanosecond pulse rise time, which ensured the fixation of the initial phase of electromagnetic oscillations. The measured values of the phase difference jitter of the channel electromagnetic oscillations amount to several percent of the oscillation period.     

Lifetime extrapolation of 650 nm InGaAlP laser diodes with or without adequate burn-in time

The 650 nm InGaAlP laser diodes are the most popular photonic device in consumer electronics. Some of these lasers do not receive adequate burn-in time before sending downstream to practical applications. Lasers without adequate burn-in time may exhibit decreasing operating current and ageing tests may not generate results that can be used to predict laser lifetime and reliability. This paper presents a unified approach that allows us to predict lifetime of lasers with either increasing or decreasing operating current in short-duration ageing tests. Methods for data processing are illustrated by case examples regarding lifetime extrapolation of the data from a 1000 h ageing test of commercially available 650 nm, InGaAlP, 10 mW lasers.     

Device fabrication by ion implantation

Ion implantation of boron and phosphorus into silicon yields material that has electrical characteristics that are similar to silicon doped by conventional techniques. These results, and the ability to control and reproduce both the number of dopant atoms and their depth distribution, have been used to considerable advantage to fabricate both discrete devices and integrated circuits by ion implantation. We have made resistors, junction diodes, hyperabrupt diodes, IMPATTS, and field effect transistors. The narrow spread in the operating characteristics and the excellent performance of these devices, illustrate the advantages gained by using ion implantation as a step in the fabrication of devices.     

涡流二极管泵输送系统性能研究

涡流二极管泵输送设备是一种新型的用于高危物料输送的无运动部件的免维修输送系统.为获得适应于该系统的设计准则并可用于准确预测输送系统的外特性,本文建立了一套理论数学模型,并通过实验方法检验理论的准确性.对比结果表明,数学模型能较准确表达系统的动态性能及时均性能,且可以反映操作参数对系统性能的影响规律.     

大功率低功耗快速软恢复SiGeC功率开关二极管

为满足电力电子电路对功率开关二极管高频化的发展要求，提出了一种大功率低功耗快速软恢复p⁺(SiGeC)-n^--n⁺异质结二极管.与常规的Si p-i-n二极管相比，在正向电流密度不超过1000 A/cm²情况下，p⁺(SiGeC)-n^--n⁺二极管的正向压降减少了约1/5，有效降低了器件的通态功耗；反向恢复时间缩短了一半多，反向峰值电流降低了约25%，软 关键词： 快速软恢复 大功率低功耗 SiGeC/Si异质结功率二极管     

Characteristics of Gain-Guided Laser Diodes with Cylindrical-Mirror Cavity

We have developed highly reliable etched-mirror laser diodes using a dry etching method. The lasers without facet-coating have been operating stably over 2500 h under automatic-power control (APC) at a power of 3 mW/facet at 50°C. The gain-guided laser diodes with a cylindrical-mirror cavity (CMC) have coaxial mirrors and a fan-shaped stripe structure. By decreasing the curvature radius of the inner facet or increasing the stripe width of the inner facet, the beam waist parallel to the junction plane can be moved outside of the laser diode, while the beam waist perpendicular to the junction plane stops at the mirror facet. A particular CMC laser has a low astigmatism of 4.1 μm and a low relative intensity of noise (RIN) less than –134 dB/Hz at 4 mW under 0–1% optical feedback without high frequency current superposition.     

A global optimization design for quasi-optics power combiner of 3mm wave solid-state sources

This paper describes a global optimization design for quasi-optics power combiner of solid-state millimeter-wave sources. The operating frequency is about 100 GHz and the oscillating sources are GaAs Gunn diodes. The source-array plane is a matrix consisting of NxN (N=3,5, ..., 2k+1, where k is positive integer) diodes. The radio frequency power of the combiner is from threefold to sevenfold larger than the sum total of the single diodes power. The global optimums of the array and the location in the cuvity of the suorce-array plane will be given by a global optimizition method.     

Generation of High-Voltage Pulses by Sharp-Recovery SiC Drift Diodes (<Emphasis Type="Italic">n</Emphasis>-Base versus <Emphasis Type="Italic">p</Emphasis>-Base Diodes)

The time characteristics of pulse generators based on sharp-recovery 4H : SiC drift diodes have been calculated. It has been found that the speed of n-base 4H-SiC diodes is superior to that of p-base diodes with the amplitude and initial pedestal in the output voltage (<5% of the amplitude) versus the time curve being the same.     

Numerical simulation of blue InGaN light-emitting diodes with polarization-matched AlGaInN electron-blocking layer and barrier layer

The effect of polarization-matched AlGaInN electron-blocking layer and barrier layer on the optical performance of blue InGaN light-emitting diodes is numerically investigated. The polarization-matched AlGaInN electron-blocking layer and barrier layer are employed in an attempt to reduce the polarization effect inside the active region of the light-emitting diodes. The simulation results show that the polarization-matched AlGaInN electron-blocking layer is beneficial for confining the electrons inside the quantum well region. With the use of both polarization-matched AlGaInN electron-blocking layer and barrier layer, the optical performance of blue InGaN light-emitting diodes is greatly improved due to the increased overlap of electron and hole wavefunctions. The method proposed in this paper can also be applied to the light-emitting diodes operating in other spectral range.     

Diagnostic and characterization of the VCSEL diodes based on GaSb

Vertical-Cavity Surface-Emitting Laser (VCSEL) diodes are among the youngest members of the semiconductor laser diode family. The main aim of our work focuses on the measurement of the basic properties (the spectral range of the laser emission, temperature and current tunability) of experimental VCSEL diode lasers based on GaSb operating in the infrared region around 4250 cm^?1. A high-resolution FTIR Bruker IFS 120 HR spectrometer with a maximum resolution of 0.0035 cm^?1 was used in the emission setup for the laser diagnostic research. The absorption spectra of atmospheric pollutants like methane, carbon monoxide and ammonia have been measured using these VCSELs for the first time.     

Numerical simulation of single layer polymer light-emitting diodes

A numerical model for the electrical properties for polymeric light-emitting diodes (PLEDs) is presented which accounts for drift- and diffusion transport, recombination and re-emission processes. The current–voltage characteristics of single layer polymer light-emitting diodes are found to be dominated by the space-charge limited bulk hole-conductivity. The device efficiency is found to increase with bias as electron current is strongly reduced by injection barrier. The operating voltage increases with increased thickness of polymer layer. The understanding of these characteristics will facilitate the further optimization of the performance of polymer LEDs.     

Research on reverse recovery characteristics of SiGeC p-i-n diodes

This paper analyses the reverse recovery characteristics and mechanism of SiGeC p-i-n diodes. Based on the integrated systems engineering (ISE) data, the critical physical models of SiGeC diodes are proposed. Based on heterojunction band gap engineering, the softness factor increases over six times, reverse recovery time is over 30% short and there is a 20% decrease in peak reverse recovery current for SiGeC diodes with 20% of germanium and 0.5% of carbon, compared to Si diodes. Those advantages of SiGeC p-i-n diodes are more obvious at high temperature. Compared to lifetime control, SiGeC technique is more suitable for improving diode properties and the tradeoff between reverse recovery time and forward voltage drop can be easily achieved in SiGeC diodes. Furthermore, the high thermal-stability of SiGeC diodes reduces the costs of further process steps and offers more freedoms to device design.     

Temperature-dependent characteristics of 4H-SiC junction barrier Schottky diodes

The current-voltage characteristics of 4H-SiC junction barrier Schottky(JBS) diodes terminated by an offset field plate have been measured in the temperature range of 25-300 C.An experimental barrier height value of about 0.5 eV is obtained for the Ti/4H-SiC JBS diodes at room temperature.A decrease in the experimental barrier height and an increase in the ideality factor with decreasing temperature are shown.Reverse recovery testing also shows the temperature dependence of the peak recovery current density and the reverse recovery time.Finally,a discussion of reducing the reverse recovery time is presented.     

Temperature-dependent characteristics of 4Hben SiC junction barrier Schottky diodes

The current-voltage characteristics of 4H-SiC junction barrier Schottky (JBS) diodes terminated by an offset field plate have been measured in the temperature range of 25-300 ℃. An experimental barrier height value of about 0.5 eV is obtained for the Ti/4H-SiC JBS diodes at room temperature. A decrease in the experimental barrier height and an increase in the ideality factor with decreasing temperature are shown. Reverse recovery testing also shows the temperature dependence of the peak recovery current density and the reverse recovery time. Finally, a discussion of reducing the reverse recovery time is presented.     

Frequency response of W-band pulsed impatts operating over extended ambient temperature

Frequency response of W-band Publsed IMPATT diodes operating over varying ambient temperature has been discussed in details. A method has been suggested to compensate the chirp fluctuation with the ambient temperature. Also discussed quantiatively the control of chirp bandwidth by bias current ramping.