Large-signal characterization of DDR silicon IMPATTs operating in millimeter-wave and terahertz regime

The authors have carried out the large-signal characterization ofsilicon-based double-drift region （DDR） impact avalanche transit time （IMPATT） devices designed to operate up to 0.5 THz using a large-signal simulation method developed by the authors based on non-sinusoidal voltage excitation. The effect of band-to-band tunneling as well as parasitic series resistance on the large-signal properties of DDR Si IMPATTs have also been studied at different mm-wave and THz frequencies. Large-signal simulation results show that DDR Si IMPATT is capable of delivering peak RF power of 633.69 mW with 7.95% conversion efficiency at 94 GHz for 50% voltage modulation, whereas peak RF power output and efficiency fall to 81.08 mW and 2.01% respectively at 0.5 THz for same voltage modulation. The simulation results are compared with the experimental results and are found to be in close agreement.

Large signal and noise properties of heterojunction Al_xGa_(1-x)As/GaAs DDR IMPATTs

Simulation studies are carried out on the large signal and noise properties of heterojunction（HT）Al_xGa_（1-x）As/GaAs double drift region（DDR） IMPATT devices at V-band（60 GHz）.The dependence of Al mole fraction on the aforementioned properties of the device has been investigated.A full simulation software package has been indigenously developed for this purpose.The large signal simulation is based on a non-sinusoidal voltage excitation model.Three mole fractions of Al and two complementary HT DDR structures for each mole fraction i.e.,six DDR structures are considered in this study.The purpose is to discover the most suitable structure and corresponding mole fraction at which high power,high efficiency and low noise are obtained from the device.The noise spectral density and noise measure of all six HT DDR structures are obtained from a noise model and simulation method.Similar studies are carried out on homojunction（HM） DDR GaAs IMPATTs at 60 GHz to compare their RF properties with those of HT DDR devices.The results show that the HT DDR device based on N-Al_xGa_（1-x）As/p-GaAs with 30%mole fraction of Al is the best one so far as large signal power output,DC to RF conversion efficiency and noise level are concerned.

GaN极性和Al组份对AlcGa1−cN/GaN双异质结IMPATTD性能的影响

GaN基碰撞雪崩渡越时间二极管(IMPATTD)是前景光明的太赫兹波源,具有输出功率高、转换效率高、体积小、集成方便等优点.构建了GaN/AlcGa1-cN/GaN和AlcGa1-cN/GaN/AlcGa1-cN双异质结构(DHS)n+/n/i/p/p+型IMPATTD,通过求解半导体器件基本方程(包括泊松方程、电流密度方程和载流子连续性方程),仿真了工作于大气低损耗窗口频率0.22 THz处的IMPATTD,计算了所设计器件的直流参数(如电场分布、归一化电流密度、击穿电压等)、大信号参数(如端电压、雪崩电流密度、端电流密度、导纳-频率关系、输出功率、转换效率等)和噪声特性参数(如噪声场分布、噪声谱密度和噪声测度等),分析了GaN极性和Al组份对AlcGa1-cN/GaN DHS IMPATTD性能的影响.本文提出了一种优化AlcGa1-cN/GaN DHS IMPATT二极管结构和性能的方法.

Prospects of a β-SiC based IMPATT oscillator for application in THz communication and growth of aβ-SiC p-n junction on a Ge modified Si〈100〉substrate to realize THz IMPATTs

The prospects ofa p＋nn＋ cubic silicon carbide （3C-SiC/fl-SiC） based IMPATT diode as a potential solidstate terahertz source is studied for the first time through a modified generalized simulation scheme. The simulation predicts that the device is capable of generating an RF power output of 63.0 W at 0.33 THz with an efficiency of 13%. The effects of parasitic series resistance on the device performance and exploitable RF power level are further simulated. The studies clearly establish the potential of 3C-SiC as a base semiconductor material for a high-power THz IMPATT device. Based on the simulation results, an attempt has been made to fabricate β-SiC based IMPATT devices in the THz region. Single crystalline, epitaxial 3C-SiC films are deposited on silicon （Si） （100） substrates by rapid thermal chemical vapour deposition （RTPCVD） at a temperature as low as 800 ℃ using a single precursor methylsilane, which contains Si and C atoms in the same molecule. No initial surface carbonization step is required in this method. A p-n junction with an n-type doping concentration of 4 × 10^24 m-3 （which is similar to the simulated design data） has been grown successfully and the characterization of the grown 3C-SiC film is reported in this paper. It is found that the inclusion of Ge improves the crystal quality and reduces the surface roughness.

超薄层常压外延工艺研究

为了满足一种3mm雪崩渡越二极管的技术要求,改进了常压外延工艺,在PE-2061S硅外延设备上,实现了100mm硅片超薄外延层的生长。外延层厚度为0.45～0.55μm,外延层与衬底之间的过渡区宽度大于0.2μm。过渡区宽度以及外延层厚度和掺杂浓度的精确控制,提高了器件的微波性能。

太赫兹二极管的研究进展及应用

太赫兹器件是太赫兹技术的核心。介绍了肖特基势垒二极管、耿氏二极管、碰撞雪崩渡越时间(IMPATT)二极管以及隧道渡越时间(TUNNETT)二极管四种典型太赫兹二极管的基本理论、器件结构和关键技术,分析了影响器件性能的主要因素,给出了优化改进器件性能的措施。阐述并比较了各种太赫兹二极管的特点以及同一种结构不同材料的太赫兹二极管特性,通过对比得出各自的优缺点及适用范围。分类总结了四种不同类型太赫兹二极管的研究进展和它们相应的应用。基于器件结构和先进的半导体材料特性,指出了不同类型太赫兹二极管的未来发展方向,描述了不同类型太赫兹二极管的应用和前景。

反向泄漏电流对GaN基雪崩渡越时间二极管性能的影响

研究了不同反向泄漏电流密度下的GaN基雪崩渡越时间(IMPATT)二极管大信号输出特性。仿真结果表明,IMPATT二极管的交流性能会随着反向泄漏电流密度的增大而显著降低。对IMPATT二极管工作时的内部特性的研究表明,引起IMPATT二极管性能衰减的主要原因是较大的反向泄漏电流并没有降低交流相位延迟,反而使交流周期中内部电场的振幅显著衰减,使交流电压和交流电流显著衰减,降低了雪崩渡越时间二极管大信号输出特性。

Potentials of GaP as millimeter wave IMPATT diode with reference to Si,GaAs and GaN

This paper presents the simulation results of DC,small-signal and noise properties of GaP based Double Drift Region( DDR) Impact Avalanche Transit Time( IMPATT) diodes. In simulation study we have considered the flat DDR structures of IMPATT diode based on GaP,GaAs,Si and GaN( wurtzite,wz) material. The diodes are designed to operate at the millimeter window frequencies of 94 GHz and 220 GHz. The simulation results of these diodes reveal GaP is a promising material for IMPATT applications based on DDR structure with high break down voltage( V_B) as compared to Si and GaAs IMPATTs. It is also encouraging to worth note GaP base IMPATT diode shows a better output power density of 4. 9 × 10~9 W/m^2 as compared to Si and GaAs based IMPATT diode. But IMPATT diode based on GaN( wz) displays large values of break down voltage,efficiency and power density as compared to Si,GaAs and GaP IMPATTs.

IMPATT功率放大器的宽带非线性特性

本文提出了双调谐回路是实现宽带微波和毫米波IMPATT功率放大的有效方法,在对放大器的小信号和大信号特性分别进行了详细的理论分析后,获得了电路参数与放大器宽带特性之间的规律,理论结果与实验相符.

SiC/GaN IMPATT二极管的交流性能研究

利用p型宽带隙材料SiC替代p型GaN,制作了一种p-SiC/n-GaN异质结双漂移(DDR)IMPATT二极管。对器件的交流大信号输出特性进行数值模拟仿真。结果表明,相比传统GaN单漂移(SDR)IMAPTT二极管,p-SiC/n-GaN新结构DDR器件的击穿电压、最佳负电导、交流功率密度和直流-交流转换效率都获得了显著提高,器件具有更宽的振荡频带。该器件新结构在交流功率密度方面具有显著的应用潜力,交流功率密度达到1.97 MW/cm;。该二极管是基于宽带隙半导体材料设计,这为GaN、SiC材料IMPATT器件的设计与制造提供参考价值。

GaN基同型异质结IMPATT二极管噪声特性研究

针对p型GaN IMPATT制造工艺仍未成熟,提出了一种InGaN/GaN n-n型异质结构来取代常规p-n结构,使GaN IMPATT二极管工作在IMPATT模式下。研究了这种n-n型InGaN/GaN碰撞电离雪崩渡越时间(IMPATT)二极管的噪声特性,与同等条件下的传统GaN基p-n结IMPATT二极管作比较。结果表明,在不同偏置电流密度和不同InGaN层厚度下,该器件的噪声特性均好于传统p-n结构。结合器件交流输出特性可以得知,InGaN/GaN同型异质结IMPATT器件不仅在功率效率上优于GaN p-n结构,其噪声性能表现亦优于传统GaN p-n结构,特别是在高频段的噪声特性优势更加明显。该研究可以为GaN基IMPATT器件的设计提供更多的思路和参考。

In_(0.4)Ga_(0.6)N/GaN异质结IMPATT二极管性能仿真研究

提出了一种In_(0.4)Ga_(0.6)N/GaN同型异质结构IMPATT二极管。传统GaN基IMPATT器件中存在P型GaN制造工艺不成熟的问题,本研究方案可成为GaN基IMPATT器件的替代设计方案。详细研究了In_(0.4)Ga_(0.6)N/GaN异质结和PN结两种不同结构IMPATT二极管的直流、交流输出特性。结果表明,In_(0.4)Ga_(0.6)N/GaN IMPATT二极管在不使用P型GaN的情况下,可达到优于传统PN结IMPATT二极管的性能。

In0.17Al0.83N/GaN IMPATT二极管的温度特性

为研究碰撞电离雪崩渡越时间(IMPATT)二极管的温度特性,采用Sentaurus软件设计了晶格匹配的In0.17Al0.83N/GaN异质结IMPATT二极管二维结构,利用漂移-扩散模型研究了温度对二极管直流及高频特性的影响,并与GaN同质结IMPATT二极管的温度特性进行了比较。结果表明,温度升高时IMPATT二极管的击穿电压增大,使异质结和同质结IMPATT二极管的射频输出功率密度分别由300 K时的1.62 MW/cm2和1.24 MW/cm2增大至500 K时的1.79 MW/cm2和1.42 MW/cm2。温度升高时二极管雪崩区宽度增大,导致异质结和同质结IMPATT二极管的直流-射频转换效率分别由300 K时的15.4%和12.1%降低至500 K时的14.2%和10.7%。相比之下,In0.17Al0.83N/GaN异质结IMPATT二极管更适合高温工作,取得的研究数据可用于指导毫米波大功率InAlN/GaN异质结IMPATT二极管的设计。

基于IMPATT管固态器件的太赫兹源

太赫兹频谱有很多优越特性,在生物医疗、安全检查及军事领域中具有重要的应用前景。太赫兹源是太赫兹波领域研究中的关键技术,制约着太赫兹技术的发展。从介绍太赫兹源的研究与发展动态出发,阐述了雪崩渡越时间二极管(IMPATT)器件的工作机理、等效分析模型及注锁牵引稳频振荡理论,给出了几种基于IMPATT管获取电子学固态太赫兹源的方法。

不同载流子输运模型对GaN IMPATT二极管直流特性的影响研究

本文利用氮化镓半导体,设计了传统的高-低结构的碰撞电离雪崩渡越时间(IMPATT)二极管,并利用漂移-扩散输运模型和流体动力学输运模型,在Sentaurus模拟器中对器件的直流特性进行了模拟研究。通过对比研究,发现漂移-扩散模型过高估计了器件内部载流子的碰撞电离率,而流体动力学模型更能精确的揭示器件内部载流子的电离过程。

Silicon Epitaxial Wafer for X Band Double Read-type DDR IMPATT Diodes by Atmosphere / Low Pressure Growth Technique

The silicon epitaxial wafter for X band double Read-type DDR IMPATT diodes has been fabricatedby normal-low pressure growth technique. The hyperabrupt impurity profile and very thin p-layer, n-layerwere achieved.

Influence of self-heating on the millimeter-wave and terahertz performance of MBE grown silicon IMPATT diodes

The influence of self-heating on the millimeter-wave(mm-wave)and terahertz(THz)performance of double-drift region(DDR)impact avalanche transit time(IMPATT)sources based on silicon(Si)has been investigated in this paper.The dependences of static and large-signal parameters on junction temperature are estimated using a non-sinusoidal voltage excited(NSVE)large-signal simulation technique developed by the authors,which is based on the quantum-corrected drift-diffusion(QCDD)model.Linear variations of static parameters and non-linear variations of large-signal parameters with temperature have been observed.Analytical expressions representing the temperature dependences of static and large-signal parameters of the diodes are developed using linear and 2nd degree polynomial curve fitting techniques,which will be highly useful for optimizing the thermal design of the oscillators.Finally,the simulated results are found to be in close agreement with the experimentally measured data.

GaN/SiC基异质结亚毫米波IMPATT二极管特性研究

碰撞电离雪崩渡越时间二极管是高频通信领域最具潜力的功率电子学器件,硅和砷化镓材料广泛用于该器件的制造中,但材料较小的禁带宽度限制了二极管的功率输出能力及直流-射频转换效率。为了克服这一问题,利用宽禁带半导体(如SiC、GaN)制造碰撞电离雪崩渡越时间二极管成为当前研究的热点。本文设计了一个新颖的n-GaN/n-4H-SiC异质结碰撞电离雪崩渡越时间二极管结构,利用漂移-扩散模型,在Sentaurus模拟软件中对该二极管的直流特性和大信号微波特性进行了详细的数值模拟研究。作为对比,本文也对具有同样结构的GaN基和4H-SiC基同质结IMPATT二极管的相关特性进行了研究。结果表明,该异质结碰撞电离雪崩渡越时间二极管的最佳工作频率为280 GHz,最大射频输出功率密度为1.69 MW/cm2,直流-射频转换效率为17.8%。研究发现,GaN/SiC异质结是制造IMPATT二极管的优选材料体系。

能量弛豫时间对氮化镓IMPATT二极管直流特性的影响

电子的能量弛豫时间受半导体材料中各种散射机制的影响,高场下能量弛豫时间不仅是电场强度的函数,也是载流子温度的函数,该参数严重影响碰撞电离雪崩渡越时间二极管的电学特性。本文利用流体动力学模型研究了不同的能量弛豫时间对氮化镓基碰撞电离雪崩渡越时间二极管直流特性的影响。研究结果表明,基于电子温度(能量)的能量弛豫时间模型能更加全面的反映器件的电学特性,进一步表明氮化镓基IMPATT二极管是工作于亚毫米波段最具潜力的器件。

氮化镓基IMPATT二极管电学特性模拟研究

基于宽禁带半导体氮化镓材料,设计了传统的高-低结构的碰撞电离雪崩渡越时间(IMPATT)二极管,并对其直流特性和高频特性进行了模拟研究。模拟结果显示该IMPATT二极管工作频率达到300GHz,输出功率为1.94W,直流-射频转换效率达到17.2%,结果表明氮化镓材料在太赫兹器件制造领域应用潜力巨大。