Figure 4 SEM
images of MoS 2  crystals grown on SiO 2  substrate
at a growth temperature of 780 °C with a MoO 3 /S ratio
of 1:20 and 25 mg NaCl. (a–d) SEM images of
MoS 2  with low magnification. High-magnification SEM images
of various shapes of CVD-grown MoS 2 : (e) three-point star,
(f) four-point star, (g) tilt boundary, (h) mirror boundary, (i, j)
six-point star, (k) seven-point star, and (l) mirror twins.