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101.
集电结耗尽层的渡越时间是影响晶体管交流放大系数和频率特性的重要参数。本文分三种情况求解了SiGe HBT集电结耗尽层宽度。建立了不同集电极电流密度下的集电结耗尽层渡越时间模型,该模型考虑了基区扩展效应。利用MATLAB对该模型进行了模拟,定量地研究了集电结反偏电压、集电区掺杂磷或砷的浓度、集电区宽度对集电结耗尽层渡越时间的影响。模拟结果表明:随着集电结反偏电压、集电区掺杂浓度以及集电区宽度的增大,集电结耗尽层渡越时间增大;集电结耗尽层渡越时间对薄基区的SiGe HBT频率特性影响显著,不能忽略。 相似文献
102.
D. Bougeard P. H. Tan M. Sabathil P. Vogl G. Abstreiter K. Brunner 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):312
We report the first resonant electronic Raman spectroscopy study of discrete electronic transitions within small p-doped self-assembled Si/Ge quantum dots (QDs). A heavy hole (hh) to light hole (lh) Raman transition with a dispersionless energy of 105 meV and a resonance energy of the hh states to virtually localised electrons at the direct band gap of 2.5 eV are observed. The hh–lh transition energy shifts to lower values with increasing annealing temperature due to significant intermixing of Si and Ge in the QDs. Structural parameters of the small Si/Ge dots have been determined and introduced into 6-band k·p valence band structure calculations. Both the value of the electronic Raman transition of localised holes as well as the resonance energy at the E0 gap are in excellent agreement with the calculations. 相似文献
103.
L. Diehl S. Mentese E. Müller D. Grützmacher H. Sigg T. Fromherz J. Faist U. Gennser Y. Campidelli O. Kermarrec D. Bensahel 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):315
This study follows up our previous investigation of the valence band (VB) intersubband emission from quantum cascade structures grown lattice matched on Si substrates. Here, Si/Si1−xGex (x=80%) heterostructures are investigated which are deposited by MBE on a virtual substrate of relaxed SiGe containing 50% of Ge. TEM analysis reveal flat and abrupt interfaces for structures grown at temperatures Tgrowth≈300°C. Intersubband absorption and photoluminescence emission manifest well-defined interfaces and good material quality. The observed intersubband line positions are found to be in good agreement with k·p model calculations for the VB. This is in contrast to the observed type II no phonons recombination which is found at consistently lower energy than expected. Finally, electrically excited intersubband emission from a strain compensated cascade structure containing three periods is presented. 相似文献
104.
研究了Si1-xGex合金半导体中无声子参与光嗅迁的产机制,对由杂质无规分布引起的无声子参与光跃迁给出了一个物理模型。用此模型计算了光跃迁偶极矩,给出了跃迁偶极矩的上限。提出了未掺杂Si1-xGex合金半导体中无声子参与光跃迁的一种跃迁机制,认为是Ge原子周围波函数畸变的集体行为。 相似文献
105.
研究了自组织生长SiGe岛(量子点)中Si组分对形状演化的影响.采用UHV/CVD方法生长了 不同Si组分的SiGe岛,用AFM对其形状和尺寸分布进行了分析,实验结果表明SiGe岛从金字 塔形向圆顶形转变的临界体积随Si组分的增大而增大.通过对量子点能量的应变能项进行修正,解释了量子点中Si组分对形状演化的影响.在特定的工艺条件下得到了单模尺寸分布的 金字塔和圆顶形量子点.结果表明,通过调节SiGe岛中的Si组分,可以实现对SiGe岛形状和 尺寸的控制.
关键词:
自组织生长SiGe岛
Si组分
临界体积 相似文献
106.
Sphere-shaped SiGe micro/nanostructures with tunable Ge composition and size formed by laser irradiation 下载免费PDF全文
《中国物理 B》2021,30(9):96104-096104
SiGe spheres with different diameters are successfully fabricated on a virtual SiGe template using a laser irradiation method. The results from scanning electron microscopy and micro-Raman spectroscopy reveal that the diameter and Ge composition of the SiGe spheres can be well controlled by adjusting the laser energy density. In addition, the transmission electron microscopy results show that Ge composition inside the Si Ge spheres is almost uniform in a well-defined, nearly spherical outline. As a convenient method to prepare sphere-shaped SiGe micro/nanostructures with tunable Ge composition and size, this technique is expected to be useful for Si Ge-based material growth and micro/optoelectronic device fabrication. 相似文献
107.
支撑光网络发展的硅基光电子技术研究 总被引:3,自引:0,他引:3
作为大规模集成电路和化合物半导体光电子器件的制造技术共同构成的一门高新技术 ,硅基光电子技术越来越受到重视 .文章着重介绍中国科学院半导体研究所外延生长SiGe/Si量子结构和Si基器件研究的结果 :采用自行设计的UHV/CVD系统 ,成功地生长出Ⅱ型SiGe/Si量子阱和量子点 ,直到 2 5 0K仍能观察到自组织生长Ge/Si(0 0 1 )量子点的发光峰 ;研制成功SiGe/Si谐振腔增强型光电二极管 (RCEPD)、Y分支MZI光调制器和多模干涉 -马赫 -曾德干涉型光开关等Si基光电子器件 ;1 .3μm处RCEPD的量子效率达到 4 .2 % ,- 5V偏压下暗电流密度 1 2 pA/ μm2 ;2× 2热光型光开关的响应时间小于 2 0 μs,两输出端关态串扰为 - 2 2dB ,通态串扰为 - 1 2dB . 相似文献
108.
109.
M. Sc. Benedikt Köstler Dr. Michael Bolte Dr. Hans-Wolfram Lerner Prof. Dr. Matthias Wagner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(58):14401-14404
SixGey alloys are emerging materials for modern semiconductor technology. Well-defined model systems of the bulk structures aid in understanding their intrinsic characteristics. Three such model clusters have now been realized in the form of the SixGey heteroadamantanes [0] , [1] , and [2] through selective one-pot syntheses starting from Me2GeCl2, Si2Cl6, and [nBu4N]Cl. Compound [0] contains six GeMe2 and four SiSiCl3 vertices, whereas one and two of the GeMe2 groups are replaced by SiCl2 moieties in compounds [1] and [2] , respectively. Chloride-ion-mediated rearrangement quantitatively converts [2] into [1] at room temperature and finally into [0] at 60 °C, which is not only remarkable in view of the rigidity of these cage structures but also sheds light on the assembly mechanism. 相似文献
110.
《Current Applied Physics》2018,18(12):1540-1545
SiGe alloy is widely used thermoelectric materials for high temperature thermoelectric generator applications. However, its high thermoelectric performance has been thus far realized only in alloys synthesized employing mechanical alloying techniques, which are time-consuming and employ several materials processing steps. In the current study, for the first time, we report an enhanced thermoelectric figure-of-merit (ZT) ∼ 1.1 at 900 °C in n-type Si80Ge20 nano-alloys, synthesized using a facile and up-scalable methodology consisting of rapid solidification at high optimized cooling rate ∼ 3.4 × 107 K/s, employing melt spinning followed by spark plasma sintering of the resulting nano-crystalline melt-spun ribbons. This enhancement in ZT > 20% over its bulk counterpart, owes its origin to the nano-crystalline microstructure formed at high cooling rates, which results in crystallite size ∼7 nm leading to high density of grain boundaries, which scatter heat-carrying phonons. This abundant scattering resulted in a very low thermal conductivity ∼2.1 Wm−1K−1, which corresponds to ∼50% reduction over its bulk counterpart and is amongst the lowest reported thus far in n-type SiGe alloys. The synthesized samples were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy, based on which the enhancement in their thermoelectric performance has been discussed. 相似文献