ABSTRACT
It wasn’t until the early 1980s when engineers and scientists started to realise that strain could be a powerful tool to modify the band structure of semiconductors. The band structure determines several important characteristics, in particular, its electronic and optical properties. The deformation potential theory, which defines the concept of strain-induced energy shift of the semiconductor, was first developed to account for the coupling between the acoustic waves and electrons in solids by Bardeen and Shockley [1]. It has been stated that the local shift of energy bands by the acoustic phonon would be produced by an equivalent extrinsic strain; hence, the energy shifts by both intrinsic and extrinsic strain can be described in the same deformation potential framework. Piezoresistance coefficients are widely used due to their simplicity in representing the semiconductor transport properties under strain. The first experimental work that reported strain effects on semiconductor transport was by Smith [2], who measured the piezoresistance coefficients for n-and p-type strained bulk silicon and germanium in 1954.
