Correlation of grain orientations and the thickness of gradient MoS₂ films

Abstract

Correlation of grain orientations, film thickness, and A1g/E12g ratios extracted from the Raman spectra of gradient MoS2.

Tuning the Optoelectronic Properties of Pulsed Laser Deposited “3D”‐MoS2 Films via the Degree of Vertical Alignment of Their Constituting Layers

“…[54][55][56] An increase of this intensity ratio, indicates the dominantly exposed MoS 2 edge sites in vertically layered MoS 2 . A direct association between the [A 1g ]/[E 1 2g ] intensity ratio and the degree of vertical orientation of layers in MoS 2 grains was recently evidenced by Chang et al [53] Figure 2b shows the T d dependence of the [A 1g ]/[E 1 2g ] peak intensity ratio. The latter is found to increase gradually with T d and reaches its maximum value at 500 °C.…”

“…It is worth recalling that the E 1 2g peak is due to the in-plane vibrations of Mo and S atoms in opposite directions while the A 1g peak arises from the out-ofplane vibrations of S atoms in opposite directions along c-axis, while Mo atoms are in rest. [51][52][53] The vibrations of A 1g and E 1 2g are preferentially excited by the edge-sites and terrace-sites (basal plane) of MoS 2 , respectively. Thereby, the intensity of the A 1g mode vibrations represents the existence of vertical MoS 2 layers, while the intensity arising due to E 1 2g mode represents the in-plane MoS 2 .…”