HBT的制作工艺

<正> 1 前言异质结双极晶体管(HBT)早已是人们所期望的超高速、超高频器件。最近已经试制出电流增益截止频率F_T和最高振荡频率F_M分别超过100GHz的AlGaAs-GaAs系HBT。由于能够把HBT的基极电阻、基区渡越时间及发射极-基极结电容做得很小,所以从本质上讲;HBT具有充当高速器件的有利的一面,但为了更有效地利用好     

HBT大信号模型及PIN/HBT集成光接收前端设计

对GP大信号模型及其参数提取方法进行了研究,并对发射极尺寸为2μm×19μm的InP/InGaAs HBT进行了建模.模型的仿真结果表明,所建模型能较为精确地表征实际HBT器件的直流和高频小信号特性.基于建立的HBT大信号模型设计并制备出InP基PIN+HBT单片集成光接收前端,经在片测试,集成前端的3dB带宽可达3GHz.     

SiGe HBT低频噪声PSPICE模拟分析

对SiGe HBT低频噪声的各噪声源进行了较全面的分析,据此建立了SPICE噪声等效电路模型,进一步用PSPICE软件对SiGe HBT的低频噪声特性进行了仿真模拟.研究了频率、基极电阻、工作电流和温度等因素对低频噪声的影响.模拟结果表明,相较于Si BJT和GaAs HBT,SiGe HBT具有更好的低频噪声特性;在低频范围内,可通过减小基极电阻、减小工作电流密度或减小发射极面积、降低器件的工作温度等措施来有效改善SiGe HBT的低频噪声特性.所得结果对SiGe HBT的设计和应用有重要意义.     

基于InP/InGaAs HBT技术的单片集成长波长光接收OEIC

采用InP/InGaAs HBT与PIN光探测器单片集成方案,对光接收光电集成电路(OEIC)的外延材料结构和生长、电路设计、制作工艺和性能测试进行了研究.基于自对准InP/InGaAs HBT工艺,实现了1.55μm波长单片集成光接收OEIC.发射极尺寸2μm×8μm的InP/InGaAs HBT直流增益为40,截止频率和最高振荡频率分别为45和54GHz;集成InGaAs PIN光探测器在-5V下响应度为0.45A/W@1.55/μm,暗电流小于10nA,-3dB带宽达到10.6GHz;研制的HBT/PIN单片集成光接收OEIC在2.5和3.0Gb/s速率非归零223-1伪随机码传输工作时可以观察到张开的眼图,灵敏度≤-15.2dBm@BER=10-9.     

基于InP/InGaAs HBT技术的单片集成长波长光接收OEIC

采用InP/InGaAs HBT与PIN光探测器单片集成方案,对光接收光电集成电路(OEIC)的外延材料结构和生长、电路设计、制作工艺和性能测试进行了研究.基于自对准InP/InGaAs HBT工艺,实现了1.55μm波长单片集成光接收OEIC.发射极尺寸2μm×8μm的InP/InGaAs HBT直流增益为40,截止频率和最高振荡频率分别为45和54GHz;集成InGaAs PIN光探测器在-5V下响应度为0.45A/W@1.55/μm,暗电流小于10nA,-3dB带宽达到10.6GHz;研制的HBT/PIN单片集成光接收OEIC在2.5和3.0Gb/s速率非归零223-1伪随机码传输工作时可以观察到张开的眼图,灵敏度≤-15.2dBm@BER=10-9.     

InP基PIN HBT光电集成器件的设计与研制

对用于光电集成电路(OEIC)的InP基异质结双极性晶体管(HBT)及PIN探测器进行了设计与研制,讨论了堆叠层结构和共享层结构2种常见的集成方式,通过实验比较,确定了共享层结构器件性能更好,并对此结构进行了改进。所研制的HBT截止频率达到30 GHz,直流增益达到100;PIN的3 dB带宽达到了15 GHz。详细介绍了器件结构及工艺流程。     

光通讯系统中的背景噪声

在设计光通讯系统时,要考虑的光谱噪声基本有两种:热噪声(亦称琼生噪声)和量子噪声(亦称散粒效应噪声)。热噪声来自探测系统内的负荷电阻和放大器(主要在前端);量子噪声来自探测系统内、外两个部分。在内部产生的量子噪声是由暗电流引起的。由外源产生的量子噪声与入射于     

版图尺寸对SiGe/Si HBT高频噪声特性的影响

从实验上研究了版图尺寸对Si/SiGe HBT高频噪声特性的影响。结果表明,在现有工艺条件下,减少外基区电阻(即减少发射极与基区间距),对降低高频噪声很显著。增加基极条数、增加条长也可减少基极电阻,降低高频噪声。发射极条宽从2μm减少为1μm,对噪声的改善很有限。对1μm或2μm条宽,40μm条长的5个基极条或9个基极条的SiGe HBT,在片测试表明,频率从0.4 GHz增加到1.2 GHz,噪声系数在2.5~4.6 dB之间变化。     

InP基长波长单片集成光接收前端的设计和制备

叙述了利用InP基长波长pin光探测器和异质结双极晶体管(HBT)单片集成实现光接收前端的设计和制备方法.pin光探测器和HBT采用共享层结构,这样的结构不仅性能优于堆叠层结构,而且制备工艺兼容.制备的HBT截止频率达到30GHz,pin光探测器的3dB带宽达到了15GHz,集成光接收前端的3dB带宽达到3GHz,跨阻放大倍数达到800.     

新型恒压控制型负阻HBT的研制进展

研究了HBT产生负阻的可能机制,通过对材料结构和器件结构的特殊设计,采用常规台面HBT工艺,先后研制出3类高电流峰谷比的恒压控制型负阻HBT.超薄基区HBT的负阻特性是由超薄基区串联电阻压降调制效应造成的,在GaAs基InGaP/GaAs和AlGaAs/GaAs体系DHBT中均得到了验证.双基区和电阻栅型负阻HBT均为复合型负阻器件.双基区负阻HBT通过刻断基区,电阻栅负阻HBT通过在集电区制作基极金属形成集电区反型层,构成纵向npn与横向pnp的复合结构,由反馈结构(pnp)的集电极电流来控制主结构(npn)的基极电流从而产生负阻特性.3类负阻HBT与常规HBT在结构和工艺上兼容,兼具HBT的高速高频特性和负阻器件的双稳、自锁、节省器件的优点.     

Analysis of the transistor-related noise in integrated p-i-n-HBToptical receiver front-ends

The equivalent-input-noise-current spectral density for a monolithically integrated optical receiver front-end using InP/InGaAs heterojunction bipolar transistors and a p-i-n photodiode is computed from a small-signal model. Particular attention is paid to the contributions to the noise from the HBT in the first stage of the amplifier. It is shown that with transistors designed for 1-10-Gb/s receivers the base current shot noise dominates in the frequency range from 10 MHz to 1 GHz, and both the base resistance thermal noise and the collector current shot noise are important at higher frequencies. Device features which determine the extent of these noise sources are identified, and ways to improve the noise performance are discussed     

Scaling and technological limitations of 1/f noise and oscillator phase noise in SiGe HBTs

This paper examines the impact of SiGe HBT scaling on 1/f noise and phase noise of oscillators and frequency synthesizers. The increase of transistor speed with scaling is shown to significantly increase the sensitivity of oscillation frequency to 1/f noise and, thus, degrade close-in phase noise, but decrease the sensitivity of oscillation frequency to base current shot noise and base resistance thermal noises. The results show that corner offset frequency defined by the intersect of the 1/f³ and 1/f² phase noise has little to do with the traditional 1/f corner frequency. The relative importance of individual noise sources in determining phase noise is examined as a function of technology scaling, device sizing, and oscillation frequency. The collector current shot noise and base resistance noise are shown to set the fundamental limits of phase noise reduction. A methodology to identify the maximum tolerable 1/f K factor is established and demonstrated for the HBTs used     

An X-Band AlGaN/GaN MMIC Receiver Front-End

This letter presents an integrated AlGaN/GaN X-band receiver front-end. This is to the authors knowledge the first published results of an integrated AlGaN/GaN MMIC receiver front-end. The receiver uses an integrated SPDT switch to reduce size, weight and cost compared to circulator based transceiver front-ends. The integrated front-end has more than 13 dB of gain and a noise figure of 3.5 dB at 11 GHz.      

A Broadband Low-Cost Direct-Conversion Receiver Front-End in 90 nm CMOS

Transistors in aggressively scaled CMOS technologies have f_T greater than 150 GHz, which exceeds requirements for most existing commercial applications below 10 GHz. Excess transistor performance can be traded-off for cost by designing out inductors. This paper presents a prototype which exploits the speed of transistors to design highly integrated broadband receiver front-ends. The inductor-less prototype operates from 2 to 5.8 GHz and dissipates 85 mW at 5 GHz while occupying 0.2 mm² active area. It provides 44 dB of gain, 3.4 dB double side band noise figure, 21 dBm in-band IIP3 in the highest gain mode and 15 dB input matching.     

Ultralow dark current GaAlAs/GaAs MSM photodetector

An interdigitated GaAlAs/GaAs metal-semiconductor-metal photodetector designed to be fully integrable with HIGFET-based digital integrated circuits and which exhibit a dark current as low as 100 pA at 10 V bias voltage is presented. Static and dynamic responsivities are reported, as well as noise properties. Photocurrents (for bias voltage higher than 4 V) comparable to those measured with a pin photodiode, and a shot noise cutoff frequency in excess of 13 GHz were recorded.<>     

Investigation of compact models for RF noise in SiGe HBTs by hydrodynamic device simulation

A comprehensive investigation of the SPICE and unified compact noise models is performed by comparison with the more fundamental hierarchical hydrodynamic device model. It is shown that the rather simple SPICE and unified compact noise models yield good results for frequencies up to 10 GHz for state-of-the-art SiGe HBTs with a low base resistance. The base noise resistance, a key parameter of the compact noise models turns out to be independent of frequency and bias. It can be well estimated based on the sheet resistance of the intrinsic and extrinsic base or with the modified circle-fit method. The unified model, which in comparison to the SPICE model considers in addition the finite transit time of shot noise, is found to be somewhat more accurate than the SPICE model, especially at higher frequencies and collector currents. But this is achieved at the expense of a transit time parameter which cannot be determined without accurate and detailed noise measurements or physics-based numerical simulations.     

An accurate analysis of noise in rectangular bipolar transistors including current crowding

An accurate analysis of noise in rectangular bipolar transistors is developed from a distributed model using a collective approach and the transport noise theory. In this model, emitter current crowding effect are taken into account and noise behaviour at intermediate and low values of source impedance is precisely described. The structure of teh equivalent lumped circuit is established, and the analytical relationships characterizing its elements in an extended range of current and frequency are given. It is shown that; (a) the active base region must be represented by a nonlinear impedance with a generalized thermal noise source; (b) for low source impedances the equivalent input voltage shot noise generator is higher than predicted by low injection theories. Furthermore it is found that emitter crowding induces a uniform and important decrease in (a) base impedance (b) thermal noise and (c) the correlation between shot noise generators of the equivalent lumped circuit. Finally it appears that classical low injection theories are valid when crowding occurs in transistors biased with high source impedances.     

Cryogenic Millimeter-Wave Receiver Using Molecular Beam Epitaxy Diodes

A millimeter-wave cryogenic receiver has been built for the 60-90-GHz frequency band using GaAs mixer diodes prepared by molecuIar beam epitaxy (MBE). The diodes are mounted in a reduced-height image rejecting waveguide mixer which is followed by a cooled parametric amplifier at 4.5-5.0 GHz. At a temperature of 18 K the receiver has a total single-sideband (SSB) system temperature of 312 K at a frequency of 81 GHz. This is the lowest system temperature ever reported for a resistive mixer receiver. The low-noise operation of the mixer is seen to be a result of 1) the short-circuiting of the noise entering the image port and 2) an MBE mixer diode with a noise temperature which is consistent with the theoretical shot noise from the junction and the thermal noise from the series resistance.     

Noise in high-gain transistors and its application to the measurement of certain transistor parameters

Noise performance of a high-gain transistor is presented. It is shown that both burst noise and flicker noise in high-gain transistors are not as important as those in low-gain units. At very small biases, less than 10 µA for the given transistor, the limiting noise of the transistor is dominated by the shot noise. In the higher bias region the thermal noise of the base resistance is the dominant noise of the transistor. It is also demonstrated that from noise measurement the base resistance rb'b, the transconductance gm, and the small signal common emitter-current gain β can be accurately determined.     

A noise model for the distributed transistor

A transistor model having a distributed base region and distributed sources of noise is analyzed. An equivalent lumped-noise model is derived. The model includes all the conventional sources of shot noise and thermal noise in the base region. It is found that the transistor shot noise is uneffected by the distributed nature of the base. Mean-square thermal noise is found to be proportional to the real part of a complex base impedance. An excess noise source due to the distributed base is found but is shown to be negligible compared to thermal noise generated in the base. The distributed-noise model reduces to the conventional lumped-noise model at low frequencies.