锗硅/硅异质结材料的化学气相淀积生长动力学模型

基于化学气相淀积(CVD)的Grove理论和Fick第一定律,提出并建立了锗硅(SiGe)/硅(Si)异质结材料减压化学气相淀积(RPCVD)生长动力学模型.与以前锗硅/硅异质结材料生长动力学模型仅考虑表面反应控制不同,本模型同时考虑了表面反应和气相传输两种控制机理,并给出了两种控制机理极限情况下的模型.本模型不仅适用于低温锗硅/硅应变异质结材料生长的表征,也适用于表征高温锗硅/硅弛豫异质结材料生长的表征.将模型计算值与实验结果进行了对比,无论是625℃低温下的应变SiGe的生长,还是900℃高温下的弛豫 关键词： SiGe/Si异质结材料 化学气相淀积生长动力学模型 Grove理论 Fick第一定律     

SiGe/Si异质结缺陷的光致发光研究

本文用光致发光(PL)光谱对Si0.87Ge0.13/Si异质结的缺陷进行了研究。对PL光谱中与SiGe外延层应变驰豫产生的失配位错相关的D-Band进行了分析,发现应变驰豫同时在SiGe层和Si衬底中诱生了位错。由于在PL光谱中观察到了D1而没有观察到D2,因此D1,D2很可能并不对应于相同的位错。通过进一步的分析,我们推测引起SiGe/Si异质结的PL光谱中D-Band的位错的微观结构很可能和Si-Si相关。     

Si/SiGe量子级联激光器研究进展

Si／SiGe量子级联激光器是一种新型的带内跃迁的红外光源，突破了Si基材料间接带隙特性对光跃迁的限制。Si/SiGe量子级联激光器的开发将为实现太赫兹有源器件的硅基集成产生深远影响。文章介绍了Si/SiGe量子级联激光器的工作原理，以及这类激光器在能带设计、材料生长和波导制作方面的最新进展。     

Si/SiGe量子级联激光器研究进展

Si/SiGe量子级联激光器是一种新型的带内跃迁的红外光源,突破了Si基材料间接带隙特性对光跃迁的限制.Si/SiGe量子级联激光器的开发将为实现太赫兹有源器件的硅基集成产生深远影响.文章介绍了Si/SiGe量子级联激光器的工作原理,以及这类激光器在能带设计、材料生长和波导制作方面的最新进展.     

SiGe/Si量子阱的低温光荧光和电注入发光

使用Si-MBE生长了阶梯形折射率分布SiGe/Si量子阱材料,在低温下观测到无声子参与的光荧光和电注入发光。阶梯形折射率分布SiGe/Si电子阱结构有利于提高发光效率。讨论了这种结构的光学和电学特性。     

Si1－xGex/Si量子阱发光材料的分子束外延生长及其结构研究

采用固源Si分子束外延,在较高的生长温度于Si(100)衬底上制备出Si1－xGex/Si量子阱发光材料。发光样品的质量和特性通过卢瑟福背散射、X射线双晶衍射及光致发光评估。背散射实验中观察到应变超晶格的反常沟道效应;X射线分析表明材料的生长是共度的、无应力释放的,结晶完整性好。低温光致发光主要是外延合金量子阱中带边激子的无声发射和横光学声子参与的激子复合。并讨论了生长温度对量于阱发光的影响。     

亚100 nm应变Si/SiGe nMOSFET阈值电压二维解析模型

本文基于二维泊松方程,建立了适用于亚100 nm应变Si/SiGe nMOSFET的阈值电压理论模型.为了保证该模型的准确性,同时考虑了器件尺寸减小所导致的物理效应,如短沟道效应,量子化效应等.通过将模型的计算结果与二维器件模拟器ISE的仿真结果进行对比分析,证明了本文提出的模型的正确性.最后,还讨论了亚100 nm器件中常规工艺对阈值电压的影响.该模型为亚100 nm小尺寸应变Si器件的分析设计提供了一定的参考. 关键词： 亚100nm 应变Si/SiGe nMOSFET 二维表面势 阈值电压     

带隙法测定SiGe/Si材料的应变状态

从固体模型理论的结果出发，计算了生长于Si（100）衬底上x值小于085的Si_1-xGe_x合金材料（能带结构为类Si结构）的间接带隙与应变的关系，结 果表明，应变的S iGe材料的带隙和完全弛豫状态下材料的带隙之差与应变呈线性关系.基于这一结果，提出了 用测量带隙来间接测定SiGe/Si应变状态的方法.用带隙法和x射线双晶衍射法测量了不同应 变状态下的SiGe/Si多量子阱材料的应变弛豫度，两者可以较好的符合，表明带隙法测量SiG e应变弛豫度是可行的. 关键词： SiGe合金 应变 带隙     

Si组分对SiGe量子点形状演化的影响

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     

Si/SiGe异质结构的硅盖层中应变对Raman谱特征的影响

应变Si/SiGe异质结构通过大剂量Ge离子注入并结合高温快速热退火制备而成。325 nm波长的紫外激光被用于调查应变Si盖层的Raman谱特征。实验发现,硅盖层中的张应变导致硅的520 cm-1的一级拉曼散射峰向低频方向偏移,峰的偏移程度反映硅盖层中横向张应力的大小约为12.5×108 N·m-2。硅盖层中的张应变并未导致1 555和2 330 cm-1的次级拉曼散射峰的变化。     

Electroluminescence from Si/SiGe quantum cascade emitters

Intersubband electroluminescence results are presented from Si/SiGe quantum cascade emitters at 3.2 THz and at temperatures up to 150 K. The effect of adding doping into the active quantum wells was studied in addition to reduced barrier widths from previous measurements. While the current through the sample is increased by the addition of doping, the emitted power is reduced through additional free carrier absorption and Coulombic scattering. Free electron laser measurements confirm the intersubband transitions in the quantum wells of the cascade devices and produce non-radiative lifetimes of 20 ps between 4 and 150 K.     

锗硅量子阱中近带边光跃迁的理论和实验研究

本文研究了SiGe/Si量子阱中近带边光跃迁的产生机制,对由杂质无规分布引起的近带边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SiGe/Si量子阱中近带边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。用MBE方法生长了掺杂SiGe/Si量子阱材料,在低温下观测到近带边光跃迁。     

Free-standing Si/SiGe micro- and nano-objects

Free-standing SiGe/Si microtubes, microneedles, helical coils, bridges and submicron vertical rings have been fabricated from elastically strained SiGe/Si heterostructures grown by ultra-high vacuum chemical vapor deposition. Three-dimensional micro- and nano-objects have been formed by self-scrolling after electron beam lithography, reactive ion etching and wet selective etching. Vertical rings with very smooth sidewalls may have applications in hot embossing lithography as well as in microelectronics and micromechanics. By adjusting the SiGe/Si bilayer thickness or Ge concentration, the diameter of tube or ring could be decreased into the nanometer scale.     

Novel vertical stack HCMOSFET with strained SiGe/Si quantum channel

A novel vertical stack heterostructure CMOSFET is investigated, which is structured by strained SiGe/Si with a hole quantum well channel in the compressively strained Si量子信道 异质结构 CMOSFET 量子论 量子阱strained SiGe/Si, quantum well channel, heterostructure CMOSFET, poly-SiGe gateProject supported by the Preresearch from National Ministries and Commissions (Grant Nos 51408061104DZ01, 51439010904DZ0101).2/2/2006 12:00:00 AM2006-01-022006-03-16A novel vertical stack heterostructure CMOSFET is investigated, which is structured by strained SiGe/Si with a hole quantum well channel in the compressively strained Sil-xGex layer for p-MOSFET and an electron quantum well channel in the tensile strained Si layer for n-MOSFET. The device possesses several advantages including： 1） the integration of electron quantum well channel with hole quantum well channel into the same vertical layer structure; 2） the gate work function modifiability due to the introduction of poly-SiGe as a gate material; 3） better transistor matching; and 4） flexibility of layout design of CMOSFET by adopting exactly the same material lays for both n-channel and p-channel. The MEDICI simulation result shows that p-MOSFET and n-MOSFET have approximately the same matching threshold voltages. Nice performances are displayed in transfer characteristic, transconductance and cut-off frequency. In addition, its operation as an inverter confirms the CMOSFET structured device to be normal and effective in function.     

Study of valence intersubband absorption in tensile strained Si/SiGe quantum wells

The hole subband structures and effective masses of tensile strained Si/Sil-yGey quantum wells are calculated by using the 6 × 6 k·p method. The results show that when the tensile strain is induced in the quantum well, the light-hole state becomes the ground state, and the light hole effective masses in the growth direction are strongly reduced while the in-plane effective masses are considerable. Quantitative calculation of the valence intersubband transition between two light hole states in a 7nm tensile strained Si/Si0.55Ge0.45 quantum well grown on a relaxed Si0.5Ge0.5 （100） substrates shows a large absorption coefficient of 8400 cm^-1.     

Si_（1－x）Ge_x／Si量子阱发光材料的分子束外延生长及其结构研究

采用固源Ｓｉ分子束外延，在较高的生长温度于Ｓｉ（１００）衬底上制备出Ｓｉ１－ｘＧｅｘ／Ｓｉ量子阱发光材料．发光样品的质量和特性通过卢瑟福背散射、Ｘ射线双晶衍射及光致发光评估．背散射实验中观察到应变超晶格的反常沟道效应；Ｘ射线分析表明材料的生长是共度的、无应力释放的，结晶完整性好．低温光致发光主要是外延合金量子阱中带边激子的无声发射和横光学声子参与的激子复合．并讨论了生长温度对量于阱发光的影响．