  Controlling the interconnection of neighboring seeds (nanoflakes) to full
coverage of the textured substrate is the main challenge for the large-scale
conformal growth of atomic-thick transition metal dichalcogenides by chemical
vapor deposition. Herein, we report on a controllable method for the conformal
growth of monolayer MoS2 on not only planar but also micro- and nano-rugged
SiO2/Si substrates via metal-organic chemical vapor deposition. The continuity
of monolayer MoS2 on the rugged surface is evidenced by scanning electron
microscopy, cross-section high-resolution transmission electron microscopy,
photoluminescence (PL) mapping, and Raman mapping. Interestingly, the
photo-responsivity (~254.5 mA/W) of as-grown MoS2 on the nano-rugged substrate
exhibits 59 times higher than that of the planar sample (4.3 mA/W) under a
small applied bias of 0.1 V. This value is record high when compared with all
previous MoS2-based photocurrent generation under low or zero bias. Such a
large enhancement in the photo-responsivity arises from a large active area for
light-matter interaction and local strain for PL quenching, where the latter
effect is the key factor and unique in the conformally grown monolayer on the
nano-rugged surface. The result is a step toward the batch fabrication of
modern atomic-thick optoelectronic devices.
