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The effect of strain-induced changes on semiconductor properties and CMOS device performances have long been studied extensively by researchers. Lim et al. [14] and Numata et al. [15] has modeled the impact of strain on the strained-Si band structure as:

(1.16)

Where x is the Ge mole fraction in Si_(1-x)Ge_x substrate. Furthermore, in [15] and [16], the energy band parameters are also calculated for strained Si material and is given by,

(1.17)

Where (∆E_g)_SiGe is the reduced band gap of SiGe from Si. Zhang and Fossum [17] have calculated the flat band voltage and built-in voltage across channel-source and drain-channel interface in MOSFETs where strained-Si have been used as channel material, and the flat band voltage is given by,

(1.18)

Where, and, the built in voltage is given by,

(1.19)

Where and

The induced channel strain (both uni-axial and bi-axial) modulates the threshold voltage of a MOSFET also. In [14], the strain induced threshold voltage shift is given by,

(1.20)

and

(1.21)

On the other hand, the impact of induced strain on the 2-D nature of electron in the inversion layer has been studied in [18] using Monte-Carlo simulation. For the behavior of holes in inversion layer of p-type strained silicon MOSFET, Michielis et al. [19] have proposed a new semi-analytical model and by using the new model, effective hole mobility has been calculated and validated with experimental data. Furthermore, Batwani et al. [20] have modeled the drain current under the influence of strain in the channel of a Si MOSFET and the expression of drift and diffusion component of output current are given by;

(1.22)

and

(1.23)

The strain engineering is explored by the researchers in modern FET structures also. Chatterjee et al. [21] have modeled the carrier transport in partially embedded strained channel of a Nanowire-Field Effect Transistor (NW-FET) and found that under tensile strain, the phonon scattering occurs at the cost of electron energy, though when compressive strain is applied, then the electron gains energy during such scattering.

Thus, strain engineering is studied theoretically by several scientists for the last few decades and its impact is still under investigation for different new materials and device structures.