  Strain provides an effective means to tune the electrical properties while
retaining the native chemical composition of the material. Unlike
three-dimensional solids, two-dimensional materials withstand higher levels of
elastic strain making it easier to tune various electrical properties to suit
the technology needs. In this work we explore the effect of uniaxial
tensile-strain on the electrical transport properties of bi- and few-layered
MoS2, a promising 2D semiconductor. Raman shifts corresponding to the in-plane
vibrational modes show a redshift with strain indicating a softening of the
in-plane phonon modes. Photo luminescence measurements reveal a redshift in the
direct and the indirect emission peaks signalling a reduction in the material
bandgap. Transport measurements show a substantial enhancement in the
electrical conductivity with a high piezoresistive gauge factor of ~ 321
superior to that for Silicon for our bi-layered device. The simulations
conducted over the experimental findings reveal a substantial reduction of the
Schottky barrier height at the electrical contacts in addition to the
resistance of MoS2. Our studies reveal that strain is an important and
versatile ingredient to tune the electrical properties of 2D materials and also
can be used to engineer high-efficiency electrical contacts for future device
engineering.
