Abstract
This study was on the optoelectronic properties of multilayered two-dimensional MoS
2
and WS
2
materials on a silicon substrate using sputtering physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques. For the first time, we report ultraviolet (UV) photoresponses under air, CO
2
, and O
2
environments at different flow rates. The electrical Hall effect measurement showed the existence of MoS
2
(n-type)/Si (p-type) and WS
2
(P-type)/Si (p-type) heterojunctions with a higher sheet carrier concentration of 5.50 × 10
5
cm
−2
for WS
2
thin film. The IV electrical results revealed that WS
2
is more reactive than MoS
2
film under different gas stimuli. WS
2
film showed high stability under different bias voltages, even at zero bias voltage, due to the noticeably good carrier mobility of 29.8 × 10
2
cm
2
/V. WS
2
film indicated a fast rise/decay time of 0.23/0.21 s under air while a faster response of 0.190/0.10 s under a CO
2
environment was observed. Additionally, the external quantum efficiency of WS
2
revealed a remarkable enhancement in the CO
2
environment of 1.62 × 10
8
compared to MoS
2
film with 6.74 × 10
6
. According to our findings, the presence of CO
2
on the surface of WS
2
improves such optoelectronic properties as photocurrent gain, photoresponsivity, external quantum efficiency, and detectivity. These results indicate potential applications of WS
2
as a photodetector under gas stimuli for future optoelectronic applications.