Impedance and switching of GaAs p-i-n diodes

The impedance of GaAs p-i-n diodes under forward bias is modeled using the two-dimensional simulation program PISCES. A parallel equivalent circuit gives almost constant resistance and capacitance over a wide range of frequencies. The intrinsic turn-off switching time of the diode, neglecting contact resistance, is determined by the sweep out time of the carriers, not by the carrier lifetime, unless this is very short. The diode current is recombination dominated at low forward bias. At higher applied voltages, this current becomes diffusion dominated if not masked by high injection conditions     

Lateral effects in high-speed photodiodes

The effect of the sheet resistance of the diffused region of a p-n junction photodiode on the diode response is discussed. A differential equation is obtained for diffused region potential in terms of its sheet resistance and the manner in which the diode is illuminated. For zero external bias and low light levels or for large back-bias, the differential equation is linear. The linear equation has been solved for steady illumination and for sinusoidally varying illumination, both falling uniformly on the diode. Current voltage equations and equivalent circuits are obtained for these cases. In the ac case, the equivalent series resistance due to the diffused region sheet resistance and equivalent junction capacitance are found to be frequency dependent. The frequency dependence is interpreted as a decrease in effective diode area at high frequencies. The frequency at which this effect begins to be important is the reciprocal of the product of the diffused region sheet resistance, the junction capacitance per unit area, and the square of the diode width. The effect is slightly dependent on diode and contact geometry; both linear and circular geometries are discussed.     

The silicon PIN diode as a microwave radar protector at megawatt levels

A silicon PIN diode developed for use as a microwave protector promises to have considerably greater reliability than gas T-R tubes. The switching action of the device results from the lowering of I layer resistance by conductivity modulation, caused either by sufficiently high microwave power levels or by applied dc bias. A theoretical analysis is presented here which yields equations for I layer resistance as a function of excitation (dc bias or microwave power). Predictions are made about the relative effectiveness of direct current or microwave power in modulating the I layer; for example, 100 ma dc bias should produce about the same injected carrier concentration as 100 kw of microwave power at 1 Gc. An experimental X-band protector consisting of an appropriately tuned PIN diode connected across a waveguide presented to low level signals an insertion loss 1 db or less when zero biased, and an insertion loss of up to 34 db at 100 ma forward bias. Measurements of temperature rise in the wafer as a function of applied X-band power indicated that the diode could protect against microwave pulses with energies of up to 38 Mw-µsec before burnout, in good agreement with theoretical predictions.     

P-I-N Diodes for Low-Frequency High-Power Switching Applications

The development of high-power low-frequency diodes, conditions for their operation, and results measured in actual circuits are described. Harmonic distortion at 500 kHz and 2 MHz has been found to decrease with increasing diode lifetime and forward-bias current. Large reverse bias voltages are necessary at low frequencies to keep the RF voltage swing from penetrating the forward conduction region. The improvement of p-i-n diode lifetimes with thicker I-layers or with planar construction has been studied and the performance of these diodes in a routing switch is reported.     

GaAs PIN二极管的新等效电路模型

基于物理原理的分析,提出了GaAs PIN二极管的一种新等效电路模型.GaAs PIN二极管被分成P n-结、基区和n-n 结三部分分别建模,总的模型由三个子模型组成,从而极大地提高了模型的准确性.相应的模型参数提取过程不要求苛刻的实验或测试条件,简便易操作.研制了15组GaAs PIN二极管来验证模型,测试结果表明模型准确地反映了GaAs PIN二极管的正向和反向特性.     

A Reconfigurable High-Gain Partially Reflecting Surface Antenna

A high-gain partially reflective surface (PRS) antenna with a reconfigurable operating frequency is presented. The operating frequency is electronically tuned by incorporating an array of phase agile reflection cells on a thin substrate above the ground plane of the resonator antenna, where the reflection phase of each cell is controlled by the bias voltage applied to a pair of varactor diodes. The new configuration enables continuous tuning of the antenna from 5.2 GHz to 5.95 GHz using commercially available varactor diodes, thus covering frequencies typically used for WLAN applications. Both the PRS and phase agile cell are analyzed, and theoretical and measured results for gain, tuning range, and radiation patterns of the reconfigurable antenna are described. The effect of the varactor diode series resistance on the performance of the antenna is also reported.      

Modelling of semiconductor diodes made of high defect concentration,irradiated, high resistivity and semi-insulating material: The capacitance–voltage characteristics

Full modelling is reported of the capacitance of a long PIN semiconductor diode with a high concentration of generation–recombination (g–r) centres and different concentrations of deep traps. There are considerable differences from the textbook results given for normal lifetime diodes which have low concentrations of g–r centres. For a low density of g–r centres, the capacitance is the usual value. That is it decreases as V^−1/2 with increasing reverse bias while it increases rapidly with increasing forward bias. For high density of g–r centres and in reverse bias a departure from this voltage dependence is observed, while in forward bias a negative capacitance appears. This agrees with experiment. From these results we present a physical understanding of the processes involved. There are specific applications of these results to radiation damaged devices, lifetime killed diodes and devices made from high resistance and semi-insulating materials, especially in the interpretation of the C–V curves to evaluate the fixed space charge density.     

Reactance influence on PIN diode attenuators

The reactive component of a PIN diode is known to be a function of current due to conductivity modulation in the I-region. This reactive component can negatively influence predicted attenuation levels in PIN diode attenuators if not properly accounted for. A figure of merit based on the PIN diode parameters, DC forward current, and operation frequency, is proposed that determines the operating conditions where this reactive component can be safely ignored. Simulations and measurement data on PIN diodes of various I-region widths verify the proposed figure of merit.     

RF model of flexible microwave single-crystalline silicon nanomembrane PIN diodes on plastic substrate

This paper reports the realization and RF modeling of flexible microwave P-type-Intrinsic-N-type (PIN) diodes using transferrable single-crystalline Si nanomembranes (SiNMs) that are monolithically integrated on low-cost, flexible plastic substrates. With high-energy, high-dose ion implantation and high-temperature annealing before nanomembrane release and transfer process, the parasitic parameters (i.e. resistance, inductance, etc.) are effectively reduced, and the flexible PIN diodes achieve good high-frequency response. With consideration of the flexible device fabrication, structure and layout configuration, a RF model of the microwave single-crystalline Si nanomembrane PIN diodes on plastic substrate is presented. The RF/microwave equivalent circuit model achieves good agreement with the experimental results of the single-crystalline SiNM PIN diodes with different diode areas, and reveals the most influential factors to flexible diode characteristics. The study provides guidelines for properly designing and using single-crystalline SiNMs for flexible RF/microwave diodes and demonstrates the great possibility of flexible monolithic microwave integrated systems.     

一种改进结构的GaAs微波PIN二极管

设计并制作了高性能GaAs微波PIN二极管.分析了GaAsPIN二极管的结构对其性能的影响,并根据分析结果改进了GaAsPIN二极管的结构.制作了常见结构和改进结构的GaAsPIN二极管,比较了不同结构的GaAsPIN二极管的测试数据,从而验证了理论分析的结果.改进后的GaAsPIN二极管制作工艺更为简单,具有良好的高频特性,截止频率达到1520.5GHz.这种改进结构的GaAs微波PIN二极管在微波电路中具有良好的应用前景.     

GaAs PIN二极管的新等效电路模型

基于物理原理的分析,提出了GaAs PIN二极管的一种新等效电路模型.GaAs PIN二极管被分成P+n-结、基区和n-n+结三部分分别建模,总的模型由三个子模型组成,从而极大地提高了模型的准确性.相应的模型参数提取过程不要求苛刻的实验或测试条件,简便易操作.研制了15组GaAs PIN二极管来验证模型,测试结果表明模型准确地反映了GaAs PIN二极管的正向和反向特性.     

Large-Signal Equivalent Circuits of Avalanche Transit-Time Devices

A large-signal analysis for IMPATT diodes is derived, which allows carrier multiplication by impact ionization to occur at every point in the diode. Therefore, the operating characteristics of IMPATT diodes with a wide range of realistic doping profiles can be investigated. For a given operating frequency, RF voltage, dc bias current, and doping profile, the admittance, power output, efficiency, bias voltage of a diode can be obtained. An equivalent circuit the diode package, microwave circuit mount and diode, is obtained experimentally. Using this circuit, the admittance of the diode is measured by a reflection-type circuit and an oscillator circuit as a function of the RF voltage, dc bias current, and frequency.     

A comparison of silicon and gallium arsenide large signal IMPATT diode behaviour between 10 and 100 GHz

A large-signal computer simulation of an IMPATT diode has been used to investigate the differences between gallium arsenide and silicon IMPATT diodes. The variations of efficiency with frequency, current density, series resistance, amount of punch-through and reverse saturation currents are all investigated.With no ‘parasitic’ effects the silicon diode efficiency remains almost constant between 10 and 100 GHz, whereas the efficiency of gallium arsenide diodes is higher than that of silicon diodes at 10 GHz but decreases to the silicon diode efficiency at 100 GHz. A lower residual avalanche particle current in gallium arsenide diodes results in a higher susceptibility to reverse saturation currents. In silicon diodes the higher material resistivity affects the efficiency more than in gallium arsenide diodes, the removal of series resistance by having a punched-through diode does not necessarily increase the efficiency. The difference between experimental results quoted in the literature and the theoretical calculations are considered in terms of these effects. By considering the differences in ionization coefficients and velocities between the materials the lower efficiency of silicon diodes compared to gallium arsenide diodes is explained, also the lower breakdown voltage of gallium arsenide diodes compared to silicon diodes of the same frequency, and the ‘forward-bias’ effect found at high frequencies in gallium arsenide diodes.     

功率PIN二极管PSpice子电路模型

提出一种改进的PIN二极管子电路模型。该模型能够反映PIN二极管的瞬态开关特性,将基区电导调制效应考虑在内。通过PSpice软件瞬态仿真PIN二极管的正向直流、反向恢复特性。利用该子电路对新型SiC材料PIN二极管建模仿真,仿真结果表明运用新材料对二极管开关性能有显著提高。     

Measurement of semiconductor junction parameters using lock-in amplifiers

A phase-sensitive detection scheme is described that allows the equivalent circuit of semiconductor diodes to be determined over a wide range of operating conditions. Under reverse bias, a direct plot may be obtained of the bias dependence of the exhaustion region width through impedance measurements. In the forward sense, the diode admittance may be measured even when large currents are flowing through the diode. The capability of the method, both to yield valuable information regarding physical conditions at the junction of the device and to give insight into the charge-transport mechanisms at the interface, is illustrated through a series of measurements on selenium rectifiers.     

基于PIN二极管加载的机载相控阵天线RCS缩减

现代飞机未来要实现射频隐身性能的最大化,就要求机载雷达的开机时间越来越短,这就为机载雷达不开机期间,相控阵天线的低RCS 隐身设计提供了可能。在天线非工作时段,加载PIN 二极管有效地减小了微带天线的RCS。PIN 二极管在正向偏置和反向偏置状态下可分别等效为电阻和电容。针对不同入射状态的平面波,依据天线感应电场分布确定PIN二极管的偏置状态,并对正向偏置状态的PIN二极管的等效电阻值进行优化,实现天线RCS的缩减。仿真计算结果表明,在天线非工作时段,优化PIN二极管的工作状态,可以实现当前情况(入射方向、频率)下天线RCS 的缩减,且RCS缩减最大可超过25 dBsm;同时又可保证天线在工作时段的辐射性能不受影响。     

基于GaAs PIN二极管的宽带大功率单片单刀双掷开关

GaAs PIN二极管具有开态电阻小、截止频率高以及功率容量大的特点,采用GaAs PIN二极管制作的开关插入损耗较小、隔离度较高、并且功率的线性较好。基于河北半导体研究所GaAs PIN工艺制造了一款单刀双掷开关芯片。该开关采用单级并联结构。通过微波在片测试,在小信号条件下,6～18 GHz范围内插入损耗小于1.45 dB、隔离度大于28 dB,输入输出反射损耗小于7.5 dB。把开关装入夹具中进行功率特性测试,在连续波输入功率37 dBm,12 GHz条件下测试输出功率仅压缩0.5 dB,具有非常好的功率特性。在4英寸(100 mm)晶圆上开关的成品率较高,具有非常好的工程应用前景。     

Reverse biased PIN diode equivalent circuit parameters at microwave frequencies

This paper attempts to fulfill the need for a quantitative analysis of the microwave equivalent steady state circuit parameters of the reverse biased PIN diode as a function of the process variables of the unit. The process variables considered include the effects of small impurity concentrations in the I region and variations in diffusion depth, surface dopant concentration, and I region width at the microwave frequency of 1 Gc/s. Using the Q of the diode as a result of a given design, it is shown that a high Q depends on having a small width, high resistivity I region, along with a shallow diffusion depth. The equivalent circuit parameters are independent of surface dopant concentration to a first approximation.     

Backward Diodes for Low-level Millimeter-Wave Detection

Backward diodes (low peak current tunnel diodes) suitable for small-signal detection applications in the millimeter-wave region have been fabricated from n-type germanium. The diodes have the dimensions and geometry of point-contact diodes. For millimeter-wave signal levels below about - 20 dbm, the current sensitivity of these units is an order of magnitude greater than that of selected existing diodes for this frequency range. When employed as millimeter-wave frequency converters, the minimum conversion loss is comparable to that of conventional diodes, but the beating oscillator power requirements may be somewhat reduced. The diode noise factor at megacycle IF frequencies is comparable to that of conventional units, and in the low audio IF range it is expected to be markedly decreased. The fabrication of these diodes is described and their initial performance at selected frequencies from 11 Gc to 300 Gc is discussed.     

Si magnetic sensor composed of two combined pin diodes

A novel highly sensitive Si magnetic sensor composed of two PIN diodes with a common n+-region is proposed, and the fundamental characteristics are shown. This magnetic sensor is operated in the double-injection states of both two PIN diodes, and may be regarded as an active magnetoresistance device which detects the resistance change of the main PIN diode due to application of the magnetic field.