The tensile strained Si, based on the misfit between Si and SiGe gives high speed and high drive current for the metal oxide silicon field effect transistors. Based on the strained Si technology, a tri-gate CMOS transistor is further applied in the current leakage control and chip performance enhancement1,2. Currently, the advanced CMOS fabrication process towards to the 90nm scale. Therefore, the conventional strain partition rule of Si/SiGe layers used for large island size (> 10mm) is not adequate for small island size (< 200 nm) due to the significant local-strain effect of the edge lattice distortion. As the result, the finite element analysis is adopted for investigation of the nona-sacle strained Si induced by lattice-mismatch3,4. In order to achieve the total system minimum energy, the Si/SiGe stacked channel of tri-gate CMOS transistor will bend upwards with a distorted lattice between Si and SiGe, as simulated by the finite element method.
We proposes a novel transient finite element model with equivalent meso-mechanics theory for studying the entropic elasticity and cooperative extensibility of double strand DNA (dsDNA). Through the proposed model, the dynamic structural transitions of the dsDNA under external force/torque can be accurately simulated within an affordable CPU time. Moreover, the proposed dsDNA model comprises the meso-mechanics equivalent theory of single molecule dsDNA, including the base-stacking interaction between DNA adjacent base pairs. Additionally, the transient stress/strain distribution of the dsDNA molecule driven by axial stretching could be then disclosed. Good agreement is achieved between the numerical simulation result and the single molecular manipulation experimental result, and the mechanical behavior of stretching nicked dsDNA could be revealed.
Atomic force microscopy (AFM) is a newly developed high resolution microscopy technique which is capable of measuring nano-scale pattern, nanofabrication, data storage and material analysis in the field of mechanical, chemical and biological. A nano-probe is the most critical component of the AFM that consists of three parts: a sharp tip, a cantilever beam and a supporting base. Our work compares the different of the spring constant of cantilevers beam between the small and the large deflection theory using finite element method (FEM) in this paper. Moreover it obtains a critical point that discrepancy in the two different deflection theory from this investigation. Then, this study will to analyze the nano-probe of three types of cantilever beam under large deflection theory as well as understand the influence on spring constant and nature frequency of the dimension of geometry.
