Electronic and Vibrational Properties of Single Layer Transition Metal Dichalcogenides (TMDC)

Two dimensional (2D) layered transition metal dichalcogenides (TMDC) have recently attracted remarkable attention due to their direct and wide band gap. These semiconductor materials can be used in electronics device and in optoelectronic devices. In semiconductor materials the electronic and vibrational properties play a fundamental role in device characterization in consequently many physical observables specifically thermal and transport properties. Here the structural optimization, electronic properties and vibrational properties of tungsten disulfide (WS
₂
) and molybdenum disulfide (MoS
₂
) have been calculated by the first principle Calculation based on density functional Theory (DFT) which is implemented on the quantum espresso. The direct band gap of WS
₂
and MoS
₂
have been found at K point from the DFT calculations are 1.98 eV and 1.9 eV. The high frequency optical phonon modes are separated from the low frequency optical phonon modes by a gap of 207 cm
^-1
for single-layer WS
₂
and 285 cm
^-1
for single-layer MoS
₂
respectively.