  The infrared (IR) photoresponse of graphene synthesized by an atmospheric
chemical vapor deposition (CVD) system using a mixture of hydrogen and methane
gases was studied. The IR sensor devices were fabricated using graphene films
transferred onto a SiO2 substrate by a lift-off process. The quality of
graphene was investigated with Raman spectroscopy and optical microscopy. The
photoresponse was recorded under the illumination of IR light of wavelength 850
nm and intensity of around 0.216 mW/cm^2. The effects of temperature and
hydrogenation on photoconductivity were also studied. It was found that the
transient response and recovery times decreased with the temperature increase.
The hydrogenation effect also caused a significant decrease in the
photoresponse of the device. Although the net change in the photoresponse for
IR light was lower at low illumination intensity levels, the transient
responses were observed around 100 times faster than the recently reported
CNT-based IR sensors.
