面向太赫兹应用的InP基肖特基二极管

Based on characteristics such as low barrier and high electron mobility of lattice matched In_0.53Ga_0.47 As layer,InP-based Schottky barrier diodes（SBDs） exhibit the superiorities in achieving a lower turn-on voltage and series resistance in comparison with GaAs ones.Planar InP-based SBDs have been developed in this paper.Measurements show that a low forward turn-on voltage of less than 0.2 V and a cutoff frequency of up to 3.4 THz have been achieved.The key factors of the diode such as series resistance and the zero-biased junction capacitance are measured to be 3.32Ωand 9.1 fF,respectively.They are highly consistent with the calculated values.The performances of the InP-based SBDs in this work,such as low noise and low loss,are promising for applications in the terahertz mixer,multiplier and detector circuits.     

Design and fabrication of 0.5 micron GaAs Schottky barrier diodes for low-noise terahertz receiver applications

Recent technological advances have made possible the development of heterodyne receivers with high sensitivity and high spectral resolution for frequencies in the range 1,000–3,000 GHz (1–3 THz). These receivers rely on GaAs Schottky barrier mixer diodes to translate the high-frequency signal to a lower frequency where amplification and signal processing are possible. At these frequencies, the diode quality is a major limitation to the performance of the receiver. The design, fabrication and DC evaluation of a diode for this frequency range is presented. A figure-of-merit cut-off frequency of over 10 THz is achieved with a record low zero biased capacitance of 0.5 fF. Results from RF tests are also given.     

GaAs Schottky diodes for THz mixing applications

The operation of GaAs Schottky barrier diodes, the critical mixer element used in heterodyne receivers for a variety of scientific applications in the terahertz frequency range, is reviewed. The constraints that the receiver system places on the diodes are considered, and the fundamental guidelines for device optimization are presented. The status of ongoing research, both experimental and theoretical, is examined. Emphasis is placed on investigations of the various effects that can limit diode performance at these high frequencies. Investigations of planar diode technology are summarized, and the potential replacement of whisker-contacted devices with planar structures is considered     

Computer study on GaAs Schottky barrier IMPATT diodes

Oscillation characteristics of GaAs Schottky barrier IMPATT diodes are studied by computer simulation. For a Schottky barrier-n-n⁺ structure, the Read condition and the just-punch-through condition are found to be optimum with respect to the efficiency and power at 30 GHz. In order to improve the efficiency, a superabrupt doping profile is proposed and a high efficiency of 32 per cent is predicted. Calculation of the frequency dependence of the efficiency shows that GaAs IMPATT diodes still have the potentiality of high efficiency oscillator at 100 GHz and they are a promising microwave source in mm-wave region.     

Schottky diodes and other devices on thin silicon membranes

The fabrication of ultra-thin silicon membranes of micron or submicron sizes with thicker supporting frames makes possible improvements in several kinds of electronic devices. We show that the series resistances of some devices can be reduced significantly, thus effecting increases in the cutoff frequencies. The resistance swing of Schottky diodes can also be raised. Initial experimentation relating to some of these applications is presented.     

4H-silicon carbide Schottky barrier diodes for microwave applications

In this paper, physical models for vertical 4H-silicon carbide (4H-SiC) Schottky diodes are used to develop a design method, where a maximum cutoff frequency for a given punch-through is achieved. The models presented are also used to extract microwave simulator computer-aided design (CAD) models for the devices. A device process was developed and Schottky diodes were fabricated in-house. Characterization of the devices was performed and compared to the theoretical models with good agreement. A demonstrator singly balanced diode mixer was simulated using the developed models. The mixer was fabricated using the in-house developed diodes, and measurements on the mixer show good agreement with the CAD simulations. A conversion loss of 5.2 dB was achieved at 850 MHz, and an excellent IIP/sub 3/ of 31 dBm at 850-MHz RF was measured, at 30-dBm P/sub LO/. These results verify the enhanced properties of the SiC Schottky diode compared to other nonwide bandgap diodes.     

Reliability and micro-structural properties of GaAs Schottky diodes for submillimeter-wave applications

Whisker contacted GaAs Schottky barrier diodes are the standard devices for mixing and multiplier applications in the THz frequency range. This is mainly due to their minimum parasitics and mature technology. But with the decreasing size of the anode contact, which is required for operation at high frequencies (up to approx. 3 THz), the reliability and the micro-structural understanding of the Schottky barrier becomes increasingly important. This contribution presents new results concerning the reliability of Schottky diodes and the physical properties of small-area Schottky junctions, especially at low current densities. For these purposes a number of different Schottky diodes have been fabricated with different epilayer doping concentrations and anode diameters. Measured I/V characteristics show that the diode current deviates considerably from the ideal thermionic current behavior with decreasing diode diameter. This deviation shows an exponential dependence on the diode voltage and is a function of the doping concentration of the active layer. For a given doping concentration in the epi-layer and decreasing anode diameter, this phenomenon shifts the minimum of the ideality factor towards higher current densities. An explanation is given in terms of a difference of the cyrstallinity of the polycrystalline platinum films on the GaAs for decreasing SiO₂ aperture size in connection with a reduced Pt mobility in the electrolyte. The reliability of Schottky barrier diodes under thermal and electrical stress has been investigated on different THz Schottky diode structures. The results show that the barrier height and the ideality factor of the fabricated structures are not affected by thermal stress. Electrical stress induced by large forward currents up to a current density of 10 kA/mm² even leads to a slight increase of the barrier height and a reduction of the series resistance.     

Numerical analysis of GaAs epitaxial-layer Schottky diodes

A computer simulation of GaAs epitaxial-layer Schottky-barrier diodes has been carried out. The present work extends previous drift-diffusion equation (DDE) Schottky-barrier diode simulations to very thin epilayers of GaAs as well as to higher forward bias voltages. Diodes having epitaxial layers of 0.12 and 1.0 µm were modeled with an emphasis on comparison with experiment. To achieve better agreement with experimental data an interfacial layer was included in the model, resulting in a voltage-dependent barrier height. The bias voltage at which the I-V characteristic becomes strongly nonideal is predicted to depend more on the potential drop across the interfacial layer than on the series resistances present in the devices studied. The separate contributions of the dynamic resistance of the junction and of the series resistances of the epitaxial and bulk regions to the total resistance were examined for forward biases up to 1.1 V.     

Investigation of GaAs Schottky barrier diodes in the THz range

The properties of GaAs Schottky barrier diodes as video detectors and mixing elements were investigated in the frequency range from 0.8–2.5 THz. For the most sensitive diode, the video responsivity and system noise temperature were measured as a function of incident laser power. The highest video responsivity was 2,000 V/W at 214μm and 60 V/W at 118μm. For five diodes differing in doping, capacitance, series resistance and anode diameter, the system noise temperature was measured at 214μm and 118μm. The best single sideband (SSB) values are 12,300 K and 24,200 K at 214μm and 118μm, respectively. The system noise temperature versus frequency is given over the range from 0.5–3 THz for two specific diodes demonstrating that the sharpness of the I–V characteristics is only of secondary importance for mixer perfomance at such high frequencies.     

GaAs planar doped barrier diodes for millimetre-wave detector applications

Epitaxially grown GaAs planar doped barrier diodes have been designed and fabricated into coplanar structures specifically for millimetre-wave zero-bias detector applications. Results at 35 GHz and 94 GHz show that the tangential sensitivity, voltage sensitivity and dynamic range of these devices can significantly exceed those of any comparable Schottky diode detector. This is the first report of such a result.<>     

太赫兹肖特基二极管技术研究进展

太赫兹肖特基二极管是太赫兹应用领域中非常重要的一种器件,它可以实现高频信号的混频和倍频,研制发展太赫兹肖特基二极管对于太赫兹技术有重要意义。本文首先介绍了太赫兹肖特基二极管的种类及性能表征,接着介绍国内外主要研究机构在太赫兹肖特基二极管方面的研制成果和进展,最后总结出研制太赫兹肖特基二极管的关键技术和发展方向。     

Microwave characterization of the properties and performance of GaAs Schottky barrier mixer diodes

Microwave measurements have been made of the equivalent circuit parameters and performance characteristics of unpackaged GaAs Schottky barrier mixer diodes. The dependence of mixer performance on series inductance, junction capacitance, and series resistance is delineated. Performance of mixer diodes in packaged and unpackaged form is compared.     

High reliability sputtered Schottky diodes on GaAs

We describe developments to improve reliability and power handling for high frequency applications in whisker-contacted Schottky barrier diode mixers, detectors and multipliers fabricated using sputtered refractory metals and silicides. The lift-off process has been used to fabricate diodes on GaAs with ideality factors of 1.18 and 1.06 for W/GaAs and TiSi_x/GaAs contacts respectively.     

Design considerations for planar Schottky barrier diodes

The cut-off frequency of the simplest planar Schottky diode on a uniformly doped n-layer of GaAs is derived. The theoretical results are given as functions of doping concentration and layer thickness with the specific contact resistance as parameter. An improved planar diode structure is presented with several short Schottky contact fingers connected in parallel. Experimental values ranging from 100 to 300 GHz agree with the calculated values when parasitic capacitances are taken into account.     

A revised boundary condition for the numerical analysis of Schottky barrier diodes

A new boundary condition for the computer simulation of Schottky barrier diodes is proposed. In this model the electron transport analysis can be extended to higher bias voltages by utilizing a current-dependent surface recombination velocity which is based on a drifted Maxwellian distribution of carrier velocities. Calculations based on this revised boundary condition predict a depletion of electrons at the Schottky boundary compared with an accumulation predicted in previously published calculations.     

GaN基肖特基二极管的场板工程

The practical design of GaN-based Schottky barrier diodes（SBDs） incorporating a field plate（FP） structure necessitates an understanding of their working mechanism and optimization criteria.In this work,the influences of the parameters of FPs upon breakdown of the diode are investigated in detail and the design rules of FP structures for GaN-based SBDs are presented for a wide scale of material and device parameters.By comparing three representative dielectric materials（SiO₂,Si₃N₄ and Al₂O₃） selected for fabricating FPs,it is found that the product of dielectric permittivity and critical field strength of a dielectric material could be used as an index to predict its potential performance for FP applications.     

Electrical characteristics of GaAs MIS Schottky diodes

The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of GaAs metal-insulator-semiconductor (MIS) Schottky barrier diodes are investigated over a wide temperature range and compared with MS diodes. The effects of the insulating layer on barrier height and carrier transport are delineated by an activation energy analysis. Excess currents observed at low forward and reverse bias have also been analyzed and their cause identified. A capacitance anomaly consistently noticed in MIS Schottky barriers is resolved by stipulating a non-uniform interfacial layer, and a self-consistent model of the GaAs MIS Schottky barrier is developed by analyzing I-V and C-V data of both MIS and MS diodes.     

用于太赫兹成像的CMOS肖特基二极管三维结构

提出了一种简单、科学、有效的高截止频率肖特基势垒二极管设计方法。通过SMIC 180 nm工艺制备的肖特基二极管的截止频率为800 GHz,分析测试结果和仿真数据优化后的肖特基势垒二极管截止频率可以达到1 THz左右。完成了包括天线、匹配电路和肖特基势垒二极管的集成探测器,在220 GHz下其测试响应率可达130 V/W,等效噪声功率估计为400 pw/。完成了陶瓷瓶内不可见液面的成像实验并取得了良好的效果。     

基于肖特基二极管的太赫兹二倍频器设计

固态倍频器是太赫兹源应用中的关键器件,如何利用非线性器件提高太赫兹倍频器件的效率是设计太赫兹固态电路的关键。本文介绍了利用肖特基二极管非线性特性设计固态太赫兹二倍频器的2种方法,即采用直接阻抗匹配和传输模式匹配设计了2种不同拓扑结构的170 GHz二倍频器,针对设计的结构模型,分别进行三维有限元电磁仿真和非线性谐波平衡仿真。仿真结果表明,在17 dBm输入功率的驱动下,倍频器在160 GHz~180 GHz输出频率范围内,倍频效率在15%左右,输出功率大于7 mW。最后对2种方法设计的倍频器结构进行了简单对比和分析,为今后太赫兹倍频研究和设计提供仿真方法。