Generalized small signal impedance for microwave BARITT diodes

A general treatment is outlined and equations are developed for the small signal impedance of microwave teach-through BARITT diodes. The results are expressed in terms of "injection phase delay," φiand "drift transit," θdangles. It is shown that substantial improvements in the negative resistance and hence efficiency of such oscillators can be expected as φiis allowed to increase, but not to exceed π/2.     

Small-signal admittance of BARITT diodes

Small-signal admittance and phasor diagrams for metal-semiconductor-metal microwave oscillator diodes (BARITT diodes) were calculated by taking previously neglected carrier diffusion and field dependence of carrier velocity into account. It was shown that the microwave performance greatly degrades with an increase of dc current density and of oscillation frequency.     

Small signal analysis and optimization of the BARITT diode

Carriers are injected into the delay path of the BARITT structure with zero drift velocity, hence, diffusion can not be neglected in the small signal analysis. The inclusion of a diffusion region adjacent to the injection plane produces a more physically reasonable approach to the small signal analysis. This analysis is accomplished through a regional approximation. The three regions are the diffusion region (where diffusion dominates the conduction process) a low field region (where drift dominates but the carrier velocity has not reached the saturation velocity) and a high field region (where the carriers drift with a saturated velocity). The inclusion of the diffusion region removes the zero-velocity singularity which results in the conventional analysis and accounts for an appreciable delay which has been previously neglected. The device characteristics are optimized for various device parameters. The optimized device length and most probable value of the negative resistance are given, and a qualitative discussion of the physical origin of the behavior of the device characteristics is given.     

Measurement of heat-flow resistance in BARITT diodes

A method for the measurement of the heat-flow and thermal resistance in baritt diodes is described. The influence of the negative thermal resistance on the microwave performance of baritt diodes is discussed.     

Small-signal noise analysis of p+?n?p+ BARITT diodes

The noise sources in BARITT diodes are described. The noise measure is calculated numerically and compared with experimental results. The optimum noise measure at 8 GHz was determined by varying the device width for given current density and doping density. The best noise measure of 9 dB was obtained for a doping of 2.5 × 1015/cm3 and a current density of 60 A/cm2.     

Design and development of high-power microwave silicon BARITT diodes

A method of design and fabrication for high-power high-frequency silicon BARITT diodes is described. Pt-Schottky BARITT structure developed in this study yielded the largest pf²product reported so far. Very good agreement between the theoretically calculated and expeximentally measured values of the reachthrough voltages and the optimum frequency of operation were observed. This proves the validity of the basic assumption used in the design calculations.     

Microwave characteristics of BARITT diodes based on silicon carbide

Microwave characteristics of barrier-injected (BARITT) diodes made of silicon carbide are investigated. It is shown that the negative resistance of p⁺-n-p⁺ structure made of different polytypes of SiC is an order of magnitude higher in absolute value in comparison with the Si p⁺-n-⁺ structure, all other factors being equal, even in the absence of trap levels (TLs). It is shown also that the dynamic negative resistance, in absolute value, the power output and efficiency increase with an increase of the concentration of traps. The effects of TLs in the band gap of the semiconductor on the impedance, power output, and efficiency of SiC BARITT diodes are examined,     

A large signal analysis of IMPATT diodes

This paper presents results on RF power output and efficiency of IMPATT oscillators obtained from a large-signal model of these devices. The results are obtained from a closed-form solution of the nonlinear equations describing a Read-type IMPATT diode. The closed-form solution is obtained by assuming a short transit time through the drift region compared to the RF period. The solution is used to obtain the large-signal diode impedance. The analysis shows that the power output of an IMPATT diode depends strongly on the series load resistance presented to the active part of the diode and that the change in diode reactance with increasing bias current also depends on the series resistance. Plots of power output as a function of frequency, bias current, and load resistance are presented. Frequency tuning of the oscillator through current variation is also discussed. Experimental results are presented and compared with the theoretical ones wherever possible. The results lead to an improved understanding of such oscillators and are extremely useful in optimizing their performance and determining their limitations.     

The small signal admittance of carbon implanted p-n diodes

In this paper we consider, in detail, how the introduction of radiation damage centres, produced by the implanation of carbon ions, affects the small signal admittance of silicon p-n diodes. Thermally stimulated capacitance measurements are used to obtain the charge states and activation energies of the damage centres. For carbon doses between 1 × 10¹¹ cm^?2 and 1 × 10¹² cm^?2 two trapping levels are observed with activation energies of E_t?E_v=0·31 eV and E_c?E_t=0·37 eV, and for doses between 5 × 10¹² cm^?2 and 5 × 10¹³ cm^?2 an extra level appears with an energy of E_c?E_t=0·25 eV. A study is made of the effects of these damage centres on the small signal capacitance and conductance of the diodes under forward bias. The results are interpreted in terms of a conductivity modulation effect, and it is proposed that this technique yields valuable information on the profile of the damage centres.     

Minority carrier effects upon the small signal and steady-state properties of Schottky diodes

Schottky diode theory is re-evaluated by applying the combined thermionic emission-diffusion theory to both the majority and minority carrier flows across the metal-semiconductor contact. Under both steady-state d.c. and small signal a.c. conditions, numerical solutions to the semiconductor transport equations subject to boundary conditions determined from the combined theory are used to investigate the effects of minority carriers upon the properties of uniformly doped Schottky diodes. High injection effects and contact limitations are shown to influence the minority carrier injection ratio and the total stored minority carrier charge. It is further shown that the small signal impedance of a large class of Schottky diodes becomes inductive under moderate forward bias.     

单量子阱激光器小信号调制时的啁啾噪声

量子阱激光器具有良好的小信号调制频率响应 ,能作为高速光通信光源采用直接调制方式进行信号传输。与普通半导体激光器一样 ,直接调制将引起啁啾 ,从而影响光纤通信系统的性能。文中对小信号调制下单量子阱激光器的啁啾特性进行了研究和分析。得出了啁啾幅度和啁啾相位与调制频率的关系。对考虑与不考虑啁啾两种情况下 ,光脉冲在常规光纤中传输时的色散特性进行了模拟分析 ,发现了啁啾对系统的高阶色散有较大影响     

AlGaInP发光二极管内量子效率测量分析

采用两种方法对650 nm AlGaInP LED内量子效率进行测量分析.一是考虑光子循环利用的影响,建立取光效率模型,使用光线追迹法模拟计算取光效率,进而反推出内量子效率.另一方法是变温L-I-V测量分析,在降温过程测量外量子效率随温度的变化,测量出一定温度范围内外量子效率出现最大值且稳定,并根据LED内部的复合机制,从而确定内量予效率值.最后分析两种测量方法,并给出了影响测量的因素.     

Effect of chromium thickness on AuCr?nSi Schottky and AuCr?n?p+ Si BARITT diodes

The effect of chromium thickness on the barrier height of AuCr?nSi Schottky diodes and the current/voltage characteristics of AuCr?n?p+Si BARITT diodes is reported. The barrier height varies from 0.81 to 0.59 eV as the chromium thickness increases from zero (no chromium) to more than 200?     

Large and small signal distortion analysis using modified Volterra series

A new approach to the Volterra analysis of analog circuits is presented. Volterra analysis is widely used for the calculation of harmonic and intermodulation distortion products. However, the analysis is limited to circuits experiencing small signal excitations and becomes inaccurate when the input signal amplitude increases, especially when MOS transistors are involved. In this paper, we analyze the cause of this drawback, which is no other than the Taylor series’ convergence properties. Moreover, we propose a solution, by calculating the nonlinearity coefficients using a different type of polynomial expansion, the Chebyshev series. This replacement improves significantly the capabilities of Volterra analysis. We also present results comparing Chebyshev series with other types of polynomial expansions. Finally, we apply the proposed method to analyze the intermodulation distortion (IMD) of a CMOS RF power amplifier, both in the small and the large signal regimes.     

AM and FM Noise of BARITT Oscillators

AM, FM, and baseband noise of a BARITT diode oscillator in the range 100 Hz-50 kHz off the carrier has been measured under various operating conditions. A simple calculation has been made, relating the baseband noise to the oscillator AM and FM noise via measured amplitude and frequency modulation sensitivities and the results have been compared with the noise measured. It is shown that, depending on the bias current applied, both AM and FM noise performance can be degraded by up-conversion. Complete removal of up-converted noise requires a high-impedance low-noise bias supply since both the diode noise and bias supply noise at baseband frequencies may be significant when up-converted. Even with all modulation suppressed, the AM and FM noise has a flicker component almost completely correlated with the diode flicker noise at baseband frequencies. The RF power dependence of the AM and FM noise has also been investigated. It is shown that the BARITT oscillator noise compares very favorably with that of IMPATT's and TEO's. Values of -142 dB/100 Hz (AM noise) and 3.5 Hz/(100 Hz)/sup 1/2/ for Q/sub ext/ = 200 (FM noise) have been measured at 30 kHz off the carrier.     

The internal electric field distribution in bilayer organic light emitting diodes

The internal electric field distribution in a bilayer 4,4^′-bis[N-(1-napthyl)-N-phenylamino]-biphenyl/tris-(8-hydroxyquinoline) aluminium organic light emitting diode has been investigated experimentally using electroabsorption spectroscopy. The experimental results have been compared to those obtained from a drift–diffusion device simulation, further validating the model and highlighting the potential worth of such modelling. With the aid of the simulation, the electric field distribution can be explained in terms of charge carrier accumulation at the interface between the two organic layers, due to the HOMO and LUMO band offsets, and charge injection into the device, demonstrating the influence of contact materials on device behaviour.     

An automated algorithm for small signal analysis of DC-DC powerconverters

Based on a generalized state-space sampled data modeling, an iterative and efficient algorithm for deriving the small signal transfer functions of any DC-DC power converter is proposed. This algorithm is suitable to be implemented in a software program as an analytical tool for automated control analysis of general DC-DC power converters. Such a tool would reduce considerably the time needed by research engineers in modeling existing and new topologies and control methods. The algorithm proposed is applicable to different kinds of linear and nonlinear control methods. It has been verified on different power converters and control methods     

Analysis of semiconductor diodes with multifrequency input signal

In this paper a closed form expression for the intermodulation output power from a semiconductor diode driven by an arbitrary number of "small-level" input signals is obtained. The effect of the intrinsic resistance of the diode material is taken into consideration through the use of the modified exponential function for the diode characteristic. It has been found that the relative harmonic distortion depends on the bias voltage, which agrees with the experimental observations. This dependence would not have been obtained had the intrinsic resistance been neglected. Also, the calculated intermodulation output power shows good agreement, for small input signal, with the published experimental results.     

The temperature dependence of internal parameters of disc laser diodes InAs/InAsSbP

For disc lasers based on the InAs/InAsSbP heterostructure with a generation wavelength of 3.03–3.06 μm, the internal quantum yield of luminescence and rates of radiative and nonradiative recombination in a temperature range of 85–120 K are determined. It is established that as the temperature increases, the relative contribution of the rate of nonradiative recombination to the density of the threshold current increases from 89.9 to 92.8%. It is shown that the most probable mechanisms of nonradiative transitions in the InAs/InAsSbP disc heterolasers can be the CHCC and CHSH Auger processes with involvement of phonons. Coefficients of total losses for two experimentally observed generation bands are determined, and the maximum level of the internal optical losses is estimated. The figure of merit of the resonator of the InAs/InAsSbP disc heterolaser is ～10⁴.     

Correct self-consistent small signal analysis of peniotron mode in rotating electron-beam devices

In this paper, we make clear that already reported self-consistent small signal analyses of gyrotron and peniotron modes in rotating electron devices is applicable only for a gyrotron mode, and not for a peniotron mode. Here, we propose the new correct self-consistent small signal analysis of the peniotron mode and show some of our numerical results which indicate the distinct characteristics of the peniotron modes from those of the gyrotron ones