Papers by Keyword: Strained Si1-xGex

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Authors: Cheng Wang, He Ming Zhang, Rong Xi Xuan, Hui Yong Hu
Abstract: Si-based strained technology is currently an important topic of concern in the microelectronics field. The stress-induced enhancement of electron mobility contributes to the improved performance of Si-based strained devices. In this paper, Based on both the electron effective mass and the scattering rate models for strained-Si1-xGex/Si (101), an analytical electron mobility model for biaxial compressive strained-Si1-xGex /Si (101) is presented. The results show that the stress doesn’t make the electron mobility increased, but the electron mobility for [100] and [001] orientations decrease with increasing Ge fraction x, especially for [010] orientation expresses a sharp decrease. This physical phenomenon can be explained as: Although the applied stress (the higher the Ge fraction, the greater the applied stress) can enhance the electron mobility, alloy disorder scattering rate markedly increase. Overall the electron mobility decreases instead. The above result suggests that not all the mobilities for Si-based strained materials enhance with the stress applied. For the biaxial strained-SiGe material represented by Ge fraction, the effect of alloy disorder scattering on the enhancement of mobility must be concerned. The result can provide theoretical basis for the understanding of the improved physical characterizations and the enhanced mobility for Si-based strained materials.
Authors: Jian Jun Song, He Ming Zhang, Hui Yong Hu, Xian Ying Dai, Rong Xi Xuan
Abstract: The intrinsic carrier concentration is the important parameter for researching strained Si1-xGex materials properties and evaluating Si-based strained devices parameters. In this paper, at the beginning of analyzing the band structure of strained Si1-xGex/(101)Si, the dependence of its effective densities of states for the conduction and valence bands (Nc, Nv) and its intrinsic carrier concentration (ni) on Ge fraction (x) and temperature were obtained. The results show that ni increases significantly due to the effect of strain in strained Si1-xGex/(101)Si. Furthermore, Nc and Nv decrease with increasing Ge fraction (x). In addition, it is also found that as the temperature becomes higher, the increase in Nc and Nv occurs. The results can provide valuable references to the understanding on the Si-based strained device physics and its design.
Authors: Jian Jun Song, Heng Sheng Shan, He Ming Zhang, Hui Yong Hu, Guan Yu Wang, Jian Li Ma, Xiao Bo Xu
Abstract: Strained Si1-xGex technology has been widely adopted to enhance hole mobility. One of the most important physical parameters is density of state near the top of valence band in strained Si1-xGex materials. In this paper, we first obtained the hole effective mass along arbitrarily k wavevector directions, the hole isotropic effective masses and density of state effective mass of hole in strained Si1-xGex/(001)Si with the framework of K.P theory. And then, model of density of state near the top of valence band in strained Si1-xGex/(001)Si materials was established, which can provide valuable references to the understanding on its material physics and theoretical basis on the other important physical parameters.
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