共查询到20条相似文献,搜索用时 31 毫秒
1.
Niu G. Cressler J.D. Zhang S. Gogineni U. Ahlgren D.C. 《Electron Devices, IEEE Transactions on》1999,46(5):1007-1015
This paper presents measurements of the avalanche multiplication factor (M-1) in SiGe HBTs using a new technique capable of separating the avalanche multiplication and Early effect contributions to the increase of collector current with collector-base bias, as well as allowing safe measurements at practical current densities. The impact of collector doping, current density, Ge profile, and operation temperature are reported for the first time using measured and simulated results from a production quality UHV/CVD SiGe HBT technology. Limitations of the technique in the presence of significant self-heating are discussed. By turning on the secondary hole impact ionization, we revealed the difference in impact ionization between strained SiGe and Si in the presence of the “dead space” effect. Despite its smaller bandgap, the compressively strained SiGe layer shows an apparent decrease in the secondary hole impact ionization rate compared to Si 相似文献
2.
Joseph A.J. Cressler J.D. Richey D.M. Niu G. 《Electron Devices, IEEE Transactions on》1999,46(7):1347-1354
A comprehensive investigation of the impact of Ge profile shape as well as the scaling of collector and base doping profiles on high-injection heterojunction barrier effects in SiGe HBTs has been conducted over the -73-85°C temperature range. The onset of Kirk effect at high current densities is shown to expose the Si/SiGe heterojunction in the collector-base space charge region, thereby inducing a conduction band barrier which negatively impacts the collector and base currents as well as the dynamic response, leading to a premature roll-off in both β and fT. In light of this, careful profile optimization is critical for emerging SiGe HBT circuit applications, since they typically operate at high current densities to realize maximum performance. We first explore the experimental consequences and electrical signature of these barrier effects over the 200-358 K temperature range for a variety of Ge profiles from an advanced UHV/CVD SiGe HBT technology. We then use extensive simulations which were calibrated to measured results to explore the sensitivity of these barrier effects to both the Ge profile shape and collector profile design, and hence investigate the optimum profile design points as a function of vertical scaling 相似文献
3.
A new analytical model for the base current of Si/SiGe/Si heterojunction bipolar transistors(HBTs) has been developed. This model includes the hole injection current from the base to the emitter, and the recombination components in the space charge region(SCR) and the neutral base. Distinctly different from other models, this model includes the following effects on each base current component by using the boundary condition of the excess minority carrier concentration at SCR boundaries: the first is the effect of the parasitic potential barrier which is formed at the Si/SiGe collector-base heterojunction due to the dopant outdlffusion from the SiGe base to the adjacent Si collector, and the second is the Ge composition grading effect. The effectiveness of this model is confirmed by comparing the calculated result with the measured plot of the base current vs. the collector-base bias voltage for the ungraded HBT. The decreasing base current with the increasing the collector-base reverse bias voltage is successfully explained by this model without assuming the short-lifetime region close to the SiGe/Si collector-base junction, where a complete absence of dislocations is confirmed by transmission electron microscopy (TEM)[1]. The recombination component in the neutral base region is shown to dominate other components even for HBTs with a thin base, due to the increased carrier storage in the vicinity of the parasitic potential barrier at collector-base heterojunction. 相似文献
4.
Jun Pan Guofu Niu Jin Tang Yun Shi Joseph A.J. Harame D.L. 《Electron Device Letters, IEEE》2003,24(12):736-738
A new substrate current-based technique for measuring the avalanche multiplication factor (M - 1) in high-speed SiGe heterojunction bipolar transistors (HBTs) is proposed. The technique enables M - 1 measurement at high operating current densities required for high-speed operation, where conventional techniques fail because of self-heating. Using the proposed technique, M - 1 was measured up to 10 mA//spl mu/m/sup 2/ on SiGe HBTs featuring 120 GHz peak f/sub T/ which occurs at J/sub C/ about 7 mA//spl mu/m/sup 2/. Implications for circuit applications are also discussed. 相似文献
5.
Jin Tang Guofu Niu Joseph A.J. Harame D.L. 《Electron Devices, IEEE Transactions on》2004,51(9):1475-1482
This work investigates the impact of collector-base (CB) junction traps on low-frequency noise in high breakdown voltage (HBV) SiGe HBTs. By comparing the base current and 1/f noise at the same internal emitter-base (EB) voltage of the standard breakdown voltage (SBV) and HBV devices, we show that the CB junction traps not only increase base current, but also contribute base current 1/f noise when high injection occurs. The individual 1/f noise contributions from the emitter-base junction traps and from the collector-base junction traps are separated. The dependence of the 1/f noise component on the corresponding base current component is determined, and shown to be different for the EB and CB junction traps. The dependence of the total 1/f noise on the total base current, however, remains the same before and after high injection occurs in the HBV device, which is approximately the same as that for the SBV device. The I/sub B/ contribution from the CB junction recombination current needs to be modeled for accurate I-V and 1/f noise modeling. 相似文献
6.
7.
A simple experimental technique is presented that enables the accurate extraction of the collector-base resistance rμ that models the impact of neutral base recombination on the ac output resistance of bipolar transistors. Measurements of ratios of rμ to the output resistance ro arising from the Early effect for SiGe HBTs allows for the quantitative determination of the impact of neutral base recombination on analog circuits that are designed to have a high output resistance. It is found that SiGe HBT structures indicative of those currently being used commercially in advanced analog processes exhibit neutral base recombination that is significant enough to severely degrade the output resistance of analog circuits, even when the output transistors experience ac base voltage drive conditions. Finally, it is shown how extraction of the ratio of r μ to ro can be a useful tool to determine the impact of parasitic potential barriers formed by boron out-diffusion at the collector-base junction on device and analog circuit performance 相似文献
8.
Zanoni E. Malik R. Pavan P. Nagle J. Paccagnella A. Canali C. 《Electron Device Letters, IEEE》1992,13(5):253-255
Impact ionization phenomena in the collector region of AlGaAs/GaAs heterojunction bipolar transistors give rise to base current reduction and reversal. These phenomena can be characterized by extracting the M -1 coefficient, which can be evaluated by measuring base current changes. Measurements of M -1 are affected at low current densities by the presence of the collector-base junction reverse current I CBO. At high current densities, three effects contribute to lower the measured M -1 value: voltage drops due to collector (R C) and base (R B) parasitic resistances, device self-heating, and lowering of the base-collector junction electric field due to mobile carriers. By appropriately choosing the emitter current value, parasitic phenomena are avoided and the behavior of M -1 as a function of the collector-base voltage V CB in AlGaAs/GaAs HBTs is accurately characterized 相似文献
9.
SiGe和SiGeC HBT速度过冲模型 总被引:1,自引:0,他引:1
建立了超薄基区SiGe和SiGeC HBT的速度过冲模型。通过求解能量平衡方程,得到电子温度分布,B-C结附近的电子温度远高于晶格温度。Ge的分布对SiGeC BHT速度分布影响很大,对于线性分布,Ge梯度越大,速度过冲越明显;Ge梯度一样时,线性分布比梯形分布的速度大。梯形分布的Si Ge HBT基区也发生速度过冲。SiGeC HBT速度过冲现象与SiGeC HBT相似。 相似文献
10.
DAI Guang-hao WANG Sheng-rong LI Wen-jie 《半导体光子学与技术》2006,12(3):150-152,193
Based on the advantages of SOI technology, the frequency performance of SiGe HBT with SOI structure has been simulated. Compared with bulk SiGe HBT, the results show that the buried oxide layer (BOX) can reduce collector-base capacitance CCB with the maximum value 89.3%, substrate-base capacitance CSB with 94. 6%, and the maximum oscillation frequency is improved by 2.7. The SOl structure improves the frequency performance of SiGe HBT, which is adaptable to high-speed and high power applications. 相似文献
11.
A velocity overshoot model of ultra-thin-base SiGe and SiGeC HBT is obtained. By deriving the Boltzmann electron temperature equation, 3000?K maxima near the collector-base junction of temperatures are found. Velocities distribution solutions considering velocity overshoot are achieved. Conclusions are that different germanium content percentage decides the maxima of overshoot velocities and base overshoot is observed. SiGeC HBT possesses approximately the same velocities as in SiGe HBT. 相似文献
12.
Burghartz J.N. Comfort J.H. Patton G.L. Meyerson B.S. Sun J.Y.-C. Stork J.M.C. Mader S.R. Stanis C.L. Scilla G.J. Ginsberg B.J. 《Electron Device Letters, IEEE》1990,11(7):288-290
In the device a SiGe epitaxial base is integrated in a structure which uses in situ doped epitaxial lateral overgrowth for the formation of the emitter window and the extrinsic base contact. Nearly ideal I -V characteristics have been achieved for a base width of 60 nm with an intrinsic base resistance of 4.6 kΩ/□ and for emitter widths down to 0.4 μm. A DC collector current enhancement factor of 3.1 was obtained relative to a Si homojunction transistor with a 1.25 times higher intrinsic base resistance. The breakdown voltage BV CBO is identical for both Si and SiGe devices, even though the collector-base depletion region is partly overlapped with the reduced-bandgap SiGe strained layer. The lower BV CEO, measured for the SiGe-base transistor, is due to the higher current gain. Based on these results the fabrication of high-speed bipolar circuits that take advantage of SiGe-base bandgap engineering seems possible using selective epitaxy emitter window (SEEW) technology 相似文献
13.
This work quantifies neutral base recombination in UHV/CVD SiGe heterojunction bipolar transistors (HBTs) using calibrated two-dimensional (2-D) simulation. The simulated collector-base conductance through neutral base recombination (NBR) modulation is far below the experimentally observed values, and hence does not explain the measured output resistance degradation under forced-IB operation. In spite of the output resistance degradation, these UHV/CVD SiGe HBTs have approximately the same base current as the silicon control, and hence higher current gain. Based on the observation of the majority carrier concentration limited recombination in the CB junction depletion layer, as opposed to the minority carrier concentration limited recombination in the neutral base, local presence of traps in the CB junction depletion layer is suggested. This explains the measured CB conductance modulation and the related output resistance degradation without compromising the current gain. Numerical simulations using traps locally introduced into the CB junctions successfully reproduced the measured collector-base conductance from simulation without appreciable degradation in current gain 相似文献
14.
15.
RF linearity characteristics of SiGe HBTs 总被引:1,自引:0,他引:1
Guofu Niu Qingqing Liang Cressler J.D. Webster C.S. Harame D.L. 《Microwave Theory and Techniques》2001,49(9):1558-1565
Two-tone intermodulation in ultrahigh vacuum/chemical vapor deposition SiGe heterojunction bipolar transistors (HBTs) were analyzed using a Volterra-series-based approach that completely distinguishes individual nonlinearities. Avalanche multiplication and collector-base (CB) capacitance were shown to be the dominant nonlinearities in a single-stage common emitter amplifier. At a given Ic an optimum Vce exists for a maximum third-order intercept point (IIP3). The IIP3 is limited by the avalanche multiplication nonlinearity at low Ic, and limited by the CCB nonlinearity at high Ic. The decrease of the avalanche multiplication rate at high Ic is beneficial to linearity in SiGe HBTs. The IIP3 is sensitive to the biasing condition because of strong dependence of the avalanche multiplication current and CB capacitance on Ic and Vce. The load dependence of linearity was attributed to the feedback through the CB capacitance and the avalanche multiplication in the CB junction. Implications on the optimization of the transistor biasing condition and transistor structure for improved linearity are also discussed 相似文献
16.
Current status and future trends of SiGe BiCMOS technology 总被引:8,自引:0,他引:8
Harame D.L. Ahlgren D.C. Coolbaugh D.D. Dunn J.S. Freeman G.G. Gillis J.D. Groves R.A. Hendersen G.N. Johnson R.A. Joseph A.J. Subbanna S. Victor A.M. Watson K.M. Webster C.S. Zampardi P.J. 《Electron Devices, IEEE Transactions on》2001,48(11):2575-2594
The silicon germanium (SiGe) heterojunction bipolar transistor (HBT) marketplace covers a wide range of products and product requirements, particularly when combined with CMOS in a BiCMOS technology. A new base integration approach is presented which decouples the structural and thermal features of the HBT from the CMOS. The trend is to use this approach for future SiGe technologies for easier migration to advanced CMOS technology generations. Lateral and vertical scaling are used to achieve smaller and faster SiGe HBT devices with greatly increased current densities. Improving both the fT and fMAX will be a significant challenge as the collector and base dopant concentrations are increased. The increasing current densities of the SiGe HBT will put more emphasis on interconnects as a key factor in limiting transistor layout. Capacitors and inductors are two very important passives that must improve with each generation. The trend toward increasing capacitance in polysilicon-insulator-silicon (MOSCAP), polysilicon-insulator-polysilicon (Poly-Poly), and metal-insulator-metal (MIM) capacitors is discussed. The trend in VLSI interconnections toward thinner interlevel dielectrics and metallization layers is counter to the requirements of high Q inductors, potentially requiring a custom last metallization layer 相似文献
17.
Qingqing Liang Cressler J.D. Guofu Niu Malladi R.M. Newton K. Harame D.L. 《Electron Devices, IEEE Transactions on》2002,49(10):1807-1813
A physics-based cutoff frequency model considering high-injection heterojunction barrier effects in SiGe HBTs is derived. Compared with other compact modeling approaches, the present model accurately captures the cutoff frequency behavior at very high current densities for SiGe HBTs with deep Si-SiGe heterojunctions. The model also offers better insight into the charge density distribution under Kirk and barrier effect in SiGe HBTs. 相似文献
18.
Cressler J.D. Comfort J.H. Crabbe E.F. Patton G.L. Stork J.M.C. Sun J.Y.-C. Meyerson B.S. 《Electron Devices, IEEE Transactions on》1993,40(3):525-541
The DC design considerations associated with optimizing epitaxial Si- and SiGe-base bipolar transistors for the 77-K environment are examined in detail. Transistors and circuits were fabricated using four different vertical profiles, three with a graded-bandgap SiGe base, and one with a Si base for comparison. All four epitaxial-base profiles yield transistors with DC properties suitable for high-speed logic applications in the 77-K environment. The differences between the low-temperature DC characteristics of Si and SiGe transistors are highlighted both theoretically and experimentally. A performance tradeoff associated with the use of an intrinsic spacer layer to reduce parasitic leakage at low temperatures and the consequent base resistance degradation due to enhanced carrier freeze-out is identified. Evidence that a collector-base heterojunction barrier effect severely degrades the current drive and transconductance of SiGe-base transistors operating at low temperatures is provided 相似文献
19.
A novel intrinsic collector-base capacitance (CCB) feedback network was incorporated into the series-connected voltage balancing (SCVB) circuit configuration to implement 10 Gbit/s SiGe modulator drivers. The driver fabricated in 0.35 mum SiGe BiCMOS process could output 9 VPP differential output swing with rise/fall time (20 to 80%) less than 27 ps. Compared with drivers using only SCVB, the power consumption could be greatly reduced from 2 to 1 W 相似文献
20.
Deep submicron transferred-substrate heterojunction bipolar transistors exhibit peaking and singularities in the unilateral power gain (U) at high frequencies. Unbounded U has been observed in some devices over a 20-110 GHz bandwidth. Associated with the effect are a strong decrease in collector-base capacitance with increased bias current, and negative conductance in the common-emitter output conductance G/sub 22/ and positive conductance in the reverse conductance G/sub 12/. Unbounded U is observed in devices operating at current densities as low as 0.56 mA//spl mu/m/sup 2/. A potential explanation of the observed characteristics is dynamic electron velocity modulation in the collector-base junction. A theoretical model for the dynamics of capacitance cancellation by electron velocity modulation is developed, and its correlation with experimental data examined. 相似文献