Effect of tunneling current on the noise characteristics of a 4H-SiC Read Avalanche diode

Noise characteristics of a Read Avalanche diode are analyzed by incorporating the tunneling mechanism of the electron into the avalanche mechanism.Analytical expressions are presented for the mean square noise voltage and noise measure in MITATT(mixed tunneling and avalanche transit time) mode operation.A wide band gap semiconductor(4H-SiC) based MITATT diode is considered to study the effect of tunneling on the noise characteristics and negative conductance.While exhibiting enough potential for 4H-SiC to be used as a terahertz source of power in the MITATT mode,our results record a noise measure of 35.18 dB at a frequency of 1.5 THz.     

GaN 基材料生长及其在光电器件领域的应用

GaN具有禁带宽，热导率高，电子饱和漂移速度大和介电常数小等特点，在高度亮发光二极管，短波长激光二极管，高性能紫外探测器和高温，高频，大功率半导体器件等领域有着广泛的应用前景。本文介绍了GaN基半导体材料的制备方法，异质结构以及在光电子和微电子器件领域的应用，并讨论了今后的发展趋势。     

Opening the terahertz window with integrated diode circuits

The terahertz region of the electromagnetic spectrum, spanning from 100 GHz through 10 THz, is of increasing importance for a wide range of scientific, military and commercial applications. This interest is spurred by the unique properties of this spectral band and the very recent development of convenient terahertz sources and detectors. However, the terahertz band is also extremely challenging, in large part because it spans the transition from traditional electronics to photonics. This paper reviews the importance of this frequency band and summarizes the efforts of scientists and engineers to span the "terahertz technology gap." The emphasis is on solid-state circuits that use nonlinear diodes to translate the functionality of microwave technology to much higher frequencies.     

多倍频程GaN 分布式功率放大器的设计与实现

分布式放大器结构是一种能够实现极宽带宽的放大电路结构.不过由于晶体管自身功率密度的限制,分布式放大器大多用于小信号放大器的设计中.第3代宽禁带半导体GaN具有击穿场强高、输出功率密度大的优点,随着GaN晶体管的发展成熟,将其应用于分布式放大器结构中能够实现宽带功率放大器.本文采用4个GaNHEMT(高电子迁移率晶体管)分立器件进行分布式功率放大器设计,并以混合集成电路工艺加工,实现了0.3 ～2.5GHz的多倍频程宽带功率放大器.最终得到的测量结果显示,功率放大器在0.3 ～ 2.5GHz的频带内,饱和输出功率大于39dBm,线性增益大于8dB,最大PAE大于15％.     

基于氮化镓器件的Boost PFC设计与损耗分析

基于硅(Si)器件的PFC Boost已被广泛研究。由于Si器件特性已经被使用接近极限,基于其的变换器特性也很难再提高。氮化镓(GaN)器件的逐渐普及为变换器性能提高到一个新的等级提供了可能。本文系统介绍一款基于GaN器件的Boost PFC的设计,从主电路设计、效率分析到控制原理。最终选用NCP1654 作为电路控制器并采用GaN HEMT及SiC二极管实现了一款300W 200kHz的PFC,最高理论效率达到98.1%。通过仿真和实验验证了系统设计,展现了宽禁带器件在提升系统效率方面的潜力。     

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...     

0.22 THz Waveguide Bandpass Filter with High Stop-Band Suppression

A terahertz (THz) waveguide band-pass filter using an iris inductive window coupled structure was designed and fabricated. The filter was designed at 0.22 THz with a pass band of 20 GHz. The measured results show that the center frequency is 0.218 THz with a pass band of 0.205 THz to 0.231 THz, the minimum insertion loss is 1.26 dB at 0.224 THz, and the return loss is less than 13.1 dB. The stop-band suppression is 65.6 dB at 0.193 THz and 51.8 dB at 0.243 THz, respectively, which means a good performance of high stop-band suppression. A good agreement exists between the measured S-parameters and the simulated ones, especially in the upper band. The proposed THz waveguide filter has potential applications in THz communications.     

具有平坦增益的X波段GaN单片功率放大器

A flat gain two-stage MMIC power amplifier with a 2.8 GHz bandwidth is successfully developed for X band frequency application based on a fully integrated micro-strip Al Ga N/Ga N HEMT technology on a semiinsulating Si C substrate. Designed with a binary-cluster matching structure integrated with RC networks and LRC networks, the developed power MMIC gets a very flat small signal gain of 15 d B with a gain ripple of 0.35 d B over 9.1–11.9 GHz at the drain bias of 20 V. These RC networks are very easy to improve the stability of used Ga N HEMTs with tolerance to the MMIC technology. Inside the frequency range of 9–11.2 GHz where the measurement system calibrated, the amplifier delivers a pulsed output power of 39 d Bm and an associated power added efficiency of about 20% at 28 V without saturation, as the available RF power is limited.     

Ⅲ族氮化物基发光二极管制造工艺

Ⅲ族氮化物是近年来半导体发光器件研究领域中的热点。由于InN,GaN,AlN及由其组成的连续变化固溶体合金所构成的半导体微结构材料,具有宽禁带宽电子漂移饱和速度高、介电常数小及导热性能好等特点,使其在制作短波长、高亮度的发光器件方面具有极其光明的前景。本文系统介绍了以氮化镓为代表的Ⅲ族氮化物基发光二极管的制造工艺。从工作原理、材料生长、掺杂和欧姆接触等各方面,介绍了各种氮化物二极管的不同器件结构和制造工艺。在介绍国际上最新制造技术的同时,对其发展前景做出了展望。     

340 GHz GaN大功率固态倍频链

随着太赫兹技术的应用和发展,对大功率太赫兹固态源的需求愈加迫切。文中基于GaN肖特基二极管(SBD)工艺设计并制造了具有高功率输出的170 GHz和340 GHz太赫兹倍频器,实现了340 GHz大功率太赫兹固态倍频链。采用多管芯GaN SBD提高器件功率承载能力,综合开展电路优化设计提升倍频性能,通过仿真研究和实验测试,验证了倍频器设计的有效性和先进性。170 GHz倍频器的实测峰值输出功率达到580 mW,倍频效率为14.5%。340 GHz倍频器的实测峰值输出功率为66 mW,倍频效率为12.5%。该太赫兹固态倍频链性能优良,在太赫兹系统中具有重要的应用价值。     

太赫兹波段FSS带通滤波器的分析与设计

用HFSS仿真软件设计并分析了太赫兹频段的频率选择表面带通滤波器。其中缝隙滤波器的中心工作频率为0.346THz,透过率达到99.37%,3 dB带宽可以达到75 GHz。3层方环级联带通滤波器的通带比缝隙滤波器通带更为平坦,3 dB带宽达到了100 GHz,矩形系数也有大幅度提高。两种滤波器在不同极化波和相同极化波不同入射角度入射时都有很好的频率稳定性,并且中心工作频率在太赫兹大气窗口,可适用于太赫兹通信。     

基于光学参量效应的太赫兹辐射源及其研究进展

太赫兹频段是电磁波谱中极具科学价值但尚待完全开发的电磁辐射区域,其中,太赫兹辐射源是影响太赫兹频段能否被广泛应用的关键器件,也是太赫兹技术研究领域的前沿问题.基于光参量效应产生太赫兹波的方法具有非线性转换效率高、波长在一定范围内连续可调、易小型化、能够在室温下稳定运转等优点,近年来得到了广泛的关注.文章介绍了光参量效应...     

氮化镓在光电子和微电子器件中的应用

综述了优良的宽禁带半导体材料GaN在光电子和微电子器件中的应用。     

S 波段GaN HEMT 宽带逆F 类高效率功率放大器设计

提出一种宽频带GaN HEMT 逆F 类功率放大器设计方法,并完成S 波段高效率功率放大器的研制。首先对改进的GaN HEMT Angelov 大信号缩放模型进行分析,确定功放管栅宽模型参数;然后通过输出电容补偿、负载牵引技术获得最佳输入、输出阻抗,设计谐波控制网络实现对谐波阻抗的峰化;最后基于宽频带、高效率原则完成电路仿真版图优化。为验证该方法,基于国产GaN HEMT(栅宽1. 25mm)设计了一款中心频率2. 9GHz,带宽大于40% 的高效率逆F 类功放,测试结果表明频带内输出功率均大于3W、漏极效率达到60%。     

A V-Band Monolithic AlGaN/GaN VCO

A V-band push-push GaN monolithic microwave integrated circuit voltage controlled oscillator (VCO) has been realized based on a 0.2 mum T-gate AlGaN/GaN high electron mobility transistor technology with an fT ~ 65 GHz. The GaN VCO delivered an output power of +11 dBm at 53 GHz with an estimated phase noise of -97 dBc/Hz at 1 MHz offset based on on-wafer measurement. To the best of our knowledge, this is the highest frequency VCO ever reported for GaN technology with a high output power at V-band, without using any buffer amplifier. This work demonstrates the potential of applying GaN technology to millimeter wave band, high power, and low phase noise frequency sources applications.     

GaN HEMT器件封装技术研究进展

GaN高电子迁移率晶体管(HEMT)器件由于其宽禁带材料的独特性能,相比硅功率器件具有击穿场强高、导通电阻低、转换速度快等优势,在智能家电、交直流转换器、光伏逆变器以及电动汽车等领域有着广泛的应用前景.但GaN HEMT器件的高功率密度和高频工作特性,给器件封装带来了极大挑战,要使其出色性能得以充分发挥,其封装结构、材...     

A 1.7-1.9 THz local oscillator source

We report on the design and performance of a /spl times/2/spl times/3/spl times/3 frequency multiplier chain to the 1.7-1.9 THz band. GaAs-based planar Schottky diodes are utilized in each stage. A W-band power amplifier, driven by a commercially available synthesizer, was used to pump the chain with 100 mW of input power. The peak measured output power at room temperature is 3 /spl mu/W at 1740 GHz. When cooled to 120 K, the chain provides more than 1.5 /spl mu/W from 1730 to 1875 GHz and produced a peak of 15 /spl mu/W at 1746 GHz.     

Room-Temperature Oscillation of Resonant Tunneling Diodes close to 2 THz and Their Functions for Various Applications

Compact and coherent source is a key component for various applications of the terahertz (THz) wave. We report on our recent results of THz oscillators using resonant tunneling diodes (RTDs). To achieve high-frequency oscillation, the electron delay time of RTD was reduced with a narrow quantum well and an optimized collector spacer thickness. Conduction loss at the air bridge connecting RTD and slot antenna, which works as a resonator and a radiator, was also reduced. By these structures, a fundamental oscillation up to 1.92 THz was obtained at room temperature. Theoretical calculation shows that an oscillation over 2 THz is further expected by improved structures of RTD and antenna. Using the offset slot antenna and two-element array configuration, high output power of 0.61 mW was obtained at 620 GHz. A direct intensity modulation of RTD oscillators up to 30 GHz, which is useful for high-speed wireless data transmission, was demonstrated. By the integration of a varactor diode, wide frequency sweep of 580–700 GHz in a single device and 580–900 GHz in a four-element array were also demonstrated. This result expands possible applications of RTD oscillators.     

GaN基和GaAs基半导体激光器的电学特性研究

介绍了一种能够全面表征半导体二极管器件的电学特性的方法,此方法结合半导体二极管的正向交流特性和直流特性,称之为正向交流小信号法。利用该方法深入地研究和对比分析了GaN基和GaAs基半导体激光器的电学特性,包括表观电容、串联电阻和理想因子。实验结果表明,对于GaN基和GaAs基半导体激光器,其开始发光的过程同步于其电容由正转变为负的过程。进一步实验结果表明,GaN基半导体激光器比GaAs基半导体激光器具有更大的串联电阻和更大的理想因子。这是由于GaN基激光器的器件工艺不够完善以及外延生长的GaN材料具有很大的位错密度。该研究为提高和改善GaN基激光器的性能提供了必要的依据以及理论指导。     

Characteristics of a far-infrared molecular laser optically pumped by a high-power CO2 laser

A molecular far-infrared (FIR) laser optically pumped by a high-power CO₂ laser, which is a powerful source for testing detectors and mixers and for FIR spectroscopy, is constructed and the performance is examined through experiments. At frequencies between 580GHz and 4.25THz, FIR output power is more than 20～30m W by pumping power of 35～81W. Amplitude stability of ±3% is obtained at 100m W output at 2.52THz for over 30 minutes when the FIR tube is cooled at 5°C by a chiller. As an application to testing mixers, FIR laser lines up to 4.25 THz are detected by Schottky barrier diodes (SBD). Further, using a SBD, performance of absolute frequency stability at 693GHz of HCOOH oscillation is measured by harmonic mixing with a 115.5GHz millimeter wave from a phase-locked Gunn oscillator. The resultant center-frequency stability is 100kHz per 10 minutes.