Tensile-strain-engineered electron–phonon coupling for high-performance n -MoS2/ p -Si photodetector

Strain induced in multilayered molybdenum disulfide (MoS2) opens a new avenue for carrier dynamics, enabling the development of high-performance optoelectronic devices, including photodetectors. The strong electron–phonon coupling (EPC) can be effectively modulated through intercalation-induced strain engineering. Ion exchange between the intercalant and MoS2 leads to interlayer expansion and lattice distortion, providing an effective route to modulate strain. Hence, here, alkali ion (Mg2+) was initially intercalated in the precursor and subsequently grown on p-Si to n-MoS2/p-Si photodetector, facilitating efficient charge transfer. The redshift of E2g1 and A1g Raman modes in n-MoS2/p-Si indicated the presence of tensile strain, which weakens the EPC in the intercalated MoS2 layer. This strain-induced suppression of the EPC enhances the carrier mobility by approximately 2.6 times and reduces the carrier transit time to about one-fourth of that in the pristine structure. These synergic characteristics make n-MoS2/p-Si an excellent photodetector with fast response and good recovery of 0.9 s (photocyclability) over five cycles and good responsivity of 0.31 A/W. In addition to this, the external quantum efficiency of about 37% is observed for the fabricated photodetector.