Design and manufacture of planar GaAs Gunn diode for millimeter wave application

GaAs-based planar Gunn diodes with AlGaAs hot electron injector have been successfully developed to be used as a local oscillator of 76 GHz in monolithic millimeter-wave integrated circuits.We designed two kinds of structure diode,one has a fixed distance between the anode and cathode,but has variational cathode area,the other has a fixed cathode area,but has different distances between two electrodes.The fabrication of Gunn diode is performed in accordance with the order of operations:cathode defining,mesa etching,anode defining,isolation,passivation,via hole and electroplating.A peak current density of 29.5 kA/cm 2 is obtained.And the characteristics of negative differential resistance and the asymmetry of the current-voltage curve due to the AlGaAs hot electron injector are discussed in detail.It is demonstrated that the smaller size of active area corresponds to the smaller current,and the shorter distance between anode and cathode also corresponds to the lower threshold voltage and higher peak current,and hot electron injector can effectively enhance the radio frequency conversion efficiency and output power.     

Investigation of chlorine-based etchants in wet and dry etching technology for an InP planar Gunn diode

Mesa etching technology is considerably important in the Gunn diode fabrication process. In this paper we fabricate InP Gunn diodes with two different kinds of chlorine-based etchants for the mesa etching for comparative study. We use two chlorine-based etchants, one is HCl-based solution (HCl/H 3 PO 4 ), and the other is Cl 2 -based gas mixture by utilizing inductively coupled plasma system (ICP). The results show that the wet etching (HCl-based) offers low cost and approximately vertical sidewall, whilst ICP system (Cl 2 -based) offers an excellent and uniform vertical sidewall, and the over-etching is tiny on the top and the bottom of mesa. And the fabricated mesas of Gunn diodes have average etching rates of ～ 0.6 μm/min and ～ 1.2 μm/min, respectively. The measured data show that the current of Gunn diode by wet etching is lower than that by ICP, and the former has a higher threshold voltage. It provides a low-cost and reliable method which is potentially applied to the fabrication of chip terahertz sources.     

Point defect determination by photoluminescence and capacitance-voltage characterization in a GaN terahertz Gunn diode

Photoluminescence （PL） measurement is used to study the point defect distribution in a GaN terahertz Gunn diode, which is able to the degrade high-field transport characteristic during further device operation. PL, secondary ion mass spectroscopy （SIMS）, transmission electron microscope （TEM）, and capacitance-voltage （C-V） measurements are used to discuss the origin of point defects responsible for the yellow luminescence in structures. The point defect densities of about 1011 cm-2 in structures are extracted by analysis of C-V characterization. After thermal annealing treatment, diminishments of point defect densities in structures are efficiently demonstrated by PL and C-V results.     

A GaAs planar Schottky varactor diode for left-handed nonlinear transmission line applications

The left-handed nonlinear transmission line(LH-NLTL) based on monolithic microwave integrated circuit(MMIC) technology possesses significant advantages such as wide frequency band,high operating frequency,high conversion efficiency,and applications in millimeter and submillimeter wave frequency multiplier.The planar Schottky varactor diode(PSVD) is a major limitation to the performance of the LH-NLTL frequency multiplier as a nonlinear component.The design and the fabrication of the diode for such an application are presented.An accurate large-signal model of the diode is proposed.A 16 GHz-39.6 GHz LH-NLTL frequency doubler using our large-signal model is reported for the first time.The measured maximum output powers of the 2nd harmonic are up to 8 dBm at 26.4 GHz,and above 0 dBm from 16 GHz to 39.6 GHz when the input power is 20 dBm.The application of the LH-NLTL frequency doubler furthermore validates the accuracy of the large-signal model of the PSVD.     

Generation of Submillimeter-Wave Radiation with GaAs Tunnett Diodes and InP Gunn Devices in a Second or Higher Harmonic Mode

Efficient second-harmonic power extraction was demonstrated recently with GaAs tunnel injection transit-time (TUNNETT) diodes up to 235 GHz and with InP Gunn devices up to 325 GHz. This paper discusses the latest theoretical and experimental results from second-harmonic power extraction at submillimeter-wave frequencies and explores the potential of using power extraction at higher harmonic frequencies to generate continuous-wave radiation with significant power levels at frequencies above 325 GHz. Initial experimental results include output power levels of more than 50 W at 356 GHz from a GaAs TUNNETT diode in a third-harmonic mode and at least 0.2–5 W in the frequency range 400–560 GHz from InP Gunn devices in a third or higher harmonic mode. The spectral output of these submillimeter-wave sources was analyzed with a simple Fourier-transform terahertz spectrometer and, up to 426 GHz, with a spectrum analyzer and appropriate harmonic mixers. Initial experimental results from a GaAs/AlAs superlattice electronic device at D-band (110–170 GHz) and J-band (170–325 GHz) frequencies are also included.     

场助InP／InGaAsP／InP半导体光电阴极异质结能带的计算

采用双曲型的渐变函数,同时考虑加偏压时引起的阴极表面空间电荷区的变化,对场助InP/TnGaAsP/InP半导体光电阴极异质结的能带结构进行了详细的分析和计算,得到了在不同材料参数时,异质结能带结构的分布曲线.计算结果指出了达到理想的异质结传输效率时,发射层的厚度和掺杂浓度、吸收层的掺杂浓度、异质结界面处渐变区宽度以及场助偏压应满足的条件.它有助于场助半导体光电阴极的结构设计和材料参数的选择.     

High-efficiency unidirectional wavefront manipulation for broadband airborne sound with a planar device

In the past decade, one-way manipulation of sound has attracted rapidly growing attention with application potentials in a plethora of scenarios ranging from ultrasound imaging to noise control. Here we propose a design of a planar device capable of unidirectionally harnessing the transmitted wavefront for broadband airborne sound. Our mechanism is to use the broken spatial symmetry to give rise to different critical angles for plane waves incident along opposite directions. Along the positive direction, the incoming sound is allowed to pass with high efficiency and be arbitrarily molded into the desired shape while any reversed wave undergoes a total reflection. We analytically derive the working bandwidth and incident angle range, and present a practical implementation of our strategy. The performance of our proposed device is demonstrated both theoretically and numerically via distinct examples of production of broadband anomalous refraction, acoustic focusing and non-diffractive beams for forward transmitted wave while virtually blocking the reversed waves. Bearing advantages of simple design, planar profile, broad bandwidth and high efficiency, our design opens the possibility for novel one-way acoustic device and may have important impact on diverse applications in need of special control of airborne sound.     

一种陶瓷径向绝缘强流二极管耐压结构设计

对外径230 mm的陶瓷绝缘板,依据强流真空二极管径向绝缘的设计思想,设计加工了“锥-柱”型阳极外壳,并在传输线内筒和阴极杆末端位置增加了均压罩和屏蔽环结构。利用静电场有限元程序计算了陶瓷-真空界面电场分布,通过对外壳细节结构以及均压罩、屏蔽环形状和位置的调整,使得真空界面上沿面场强和三结合点处场强均得到了有效控制。在单线长脉冲加速器上进行了实验研究,结果显示,二极管能够耐受400 kV、脉宽大于200 ns的脉冲电压,运行稳定,达到了理论设计要求。     

一种陶瓷径向绝缘强流二极管耐压结构设计

 对外径230 mm的陶瓷绝缘板,依据强流真空二极管径向绝缘的设计思想,设计加工了“锥-柱”型阳极外壳,并在传输线内筒和阴极杆末端位置增加了均压罩和屏蔽环结构。利用静电场有限元程序计算了陶瓷-真空界面电场分布,通过对外壳细节结构以及均压罩、屏蔽环形状和位置的调整,使得真空界面上沿面场强和三结合点处场强均得到了有效控制。在单线长脉冲加速器上进行了实验研究,结果显示,二极管能够耐受400 kV、脉宽大于200 ns的脉冲电压,运行稳定,达到了理论设计要求。     

强流电子束二极管绝缘子分析与设计

对应用在Tesla型强流加速器中的电子束二极管绝缘子进行了仿真,发现电场增强区域与实际发生击穿区域基本一致。从绝缘子沿面电场分布、电力线和绝缘子表面所成角度分布以及材料缺陷等方面分析了击穿发生的原因。认为材料中存在缺陷是导致绝缘子发生击穿的主要原因,局部场增强和非最优化结构设计促成了击穿的发生。对影响绝缘子沿面电场分布的同轴线关键位置进行了设计,得出了阳极倒角半径和阴极屏蔽环半径两个参量的最佳取值范围。     

强流电子束二极管绝缘子分析与设计

对应用在Tesla型强流加速器中的电子束二极管绝缘子进行了仿真,发现电场增强区域与实际发生击穿区域基本一致。从绝缘子沿面电场分布、电力线和绝缘子表面所成角度分布以及材料缺陷等方面分析了击穿发生的原因。认为材料中存在缺陷是导致绝缘子发生击穿的主要原因,局部场增强和非最优化结构设计促成了击穿的发生。对影响绝缘子沿面电场分布的同轴线关键位置进行了设计,得出了阳极倒角半径和阴极屏蔽环半径两个参量的最佳取值范围。     

InAlAs/GaSbAs/InP DHBT与InP/GaSbAs/InP DHBT性能比较分析

双异质结双极晶体管(DHBT)的性能与发射区-基区(E-B) 异质结和基区-集电区(B-C)异质结的能带突变类型关系密切, 本文基于热场发射-扩散模型, 对两类不同能带结构类型的新型DHBT的性能做了比较分析. 结论表明: 与作为当今研究热点的E-B和B-C异质结构均为全交错II型能带结构的InP/GaSbAs/InP DHBT的性能相比, E-B异质结采用传统I型、B-C异质结采用交错II型的一类新型能带结构的InAlAs/GaSbAs/InP DHBT虽然在开启电压上更高, 但具有更好的电流驱动能力、直流增益和高频性能.     

有限宽平板波导中的克尔空间孤子及全光器件的设计

利用数值模拟的方法研究了倾斜入射的傍轴光束在有限宽非线性平板波导内的传输规律.研究发现,当不同波长相同束宽的光束各以临界功率倾斜入射波导时,如果倾斜角、入射点都一样,它们将沿大致相同的周期性的Z字形路径传输;如果光束功率进一步增大,相邻反射点之间的间距随传输距离有逐渐变大的趋势,Z字形路径不再有严格的周期性;当功率相当大时,光束将沿波导z方向传输,不再在波导的两个边界之间来回反射.利用倾斜入射光束在波导内的传输路径随功率而变的特点,设计了一个功率开关和一个光时分解复用器. 关键词： 空间光孤子 有限宽非线性平板波导 全光器件     

Hybrid-anode structure designed for a high-performance quasi-vertical GaN Schottky barrier diode

A quasi-vertical GaN Schottky barrier diode with a hybrid anode structure is proposed to trade off the on-resistance and the breakdown voltage. By inserting a SiN dielectric between the anode metal with a relatively small length, it suppresses the electric field crowding effect without presenting an obvious effect on the forward characteristics. The enhanced breakdown voltage is ascribed to the charge-coupling effect between the insulation dielectric layer and GaN. On the other hand, the current density is decreased beneath the dielectric layer with the increasing length of the SiN, resulting in a high on-resistance. Furthermore, the introduction of the field plate on the side wall forms an metal-oxide-semiconductor (MOS) channel and decreases the series resistance, but also shows an obvious electric field crowding effect at the bottom of the mesa due to the quasi-vertical structure.     

GaAs与InP半导体光导开关特性实验研究

利用Ⅲ-Ⅴ族化合物半导体材料砷化镓(GaAs)和磷化铟(InP)及其掺杂材料制作的光导开关具有很好的时间响应及高功率输出特性.比较了这两种材料制作的不同电极间隙类型的光导开关的开关时间响应速度、导通光能与饱和触发激光能量、线性与非线性工作模式及触发稳定性等特性.结果表明,利用InP和GaAs两种材料制作的光导开关都具有达到皮秒级的超快时间响应,其对时间最佳响应与偏置电场有关.两种开关的多次触发时间抖动在几个皮秒范围,输出电压峰峰值抖动优于10%.GaAs开关的非线性工作电场阈值比InP开关低,更容易实现非线性输出.     

InAIAs／GaSbAs／InPDHBT与InP／GaSbAs／InPDHBT性能比较分析

双异质结双极晶体管（DHBT）的性能与发射区-基区（E．B）异质结和基区．集电区（B．C）异质结的能带突变类型关系密切,本文基于热场发射．扩散模型,对两类不同能带结构类型的新型DHBT的性能做了比较分析．结论表明：与作为当今研究热点的E．B和B．C异质结构均为全交错II型能带结构的InP／GaSbAs／InPDHBT的性能相比,E．B异质结采用传统I型、B．C异质结采用交错II型的一类新型能带结构的InAlAs／GaSbAs／InPDHBT虽然在开启电压上更高,但具有更好的电流驱动能力、直流增益和高频性能．     

Probability distribution of normalized structure factor magnitudes for a centrosymmetric crystal with planar molecules in the unit cell

The reasons and conditions for applicability of the Cauchy distribution law for crystal structure factor components are discussed. It is shown that the standardized structure factors of centrosymmetric crystals are quite prone to be Cauchy distributed for crystals having planar molecules in their unit cells.     

Emergence of a multidomain regime and spatiotemporal chaos in Gunn diodes under impact ionization conditions

Nonlinear spatiotemporal dynamics of carrier densities in Gunn diodes under impact ionization conditions is numerically investigated using a set of model partial differential equations. Numerical results show that a multidomain regime emerges as a result of the decrease in domain size caused by impact ionization, and that the spatiotemporal evolution of the domains becomes chaotic in the presence of strong impact ionization.     

耦合同轴磁绝缘传输线的低阻抗大面积轫致辐射二极管设计

为了设计与前端低阻抗同轴磁绝缘传输线耦合的大面积轫致辐射二极管,提出了一种利用锥形磁绝缘传输线（MITL）结合阴极开孔结构来对电子输运进行调节的二极管设计方案。该结构的主要特点是在不外加电子输运调控装置的前提下,利用大角度的入射电子产生轫致辐射,在靠近二极管出射窗附近形成大面积准均匀辐射区。采用二维粒子模拟与蒙特卡罗模拟（MCNP 4C）相结合的数值模拟方法对二极管进行了模拟和分析,对于如何构建更好反映角向均匀的MCNP源提出了新的想法。模拟结果表明,该设计方案可以实现在不外加电子输运调控装置的情况下,在二极管后端得到均匀大面积轫致辐射区。     

强流束二极管绝缘子结构设计与实验研究

 介绍了一种应用于强流束二极管的径向绝缘结构,并对其在纳秒脉冲条件下的沿面闪络放电现象进行了研究。使用计算机模拟静电场的方法,对锥形结构绝缘子表面的电场分布进行了研究,优化了几何结构参数。在脉宽为40 ns,重复频率100 Hz的脉冲功率源上对绝缘子进行了实验研究。在历时18个月及100 000次脉冲实验后,发现绝缘子表面具有明显的树枝状放电现象,树枝状放电的根部碳化严重,绝缘子深度方向被完全击穿碳化,出现孔洞。基于固-液交界面闪络特性,对树枝状放电的可能原因进行了探讨。