  We report the photoresponse of vertically aligned graphene upon IR
irradiation at room temperature. Four probe measurements have shown electrical
switching in I-V characteristics during pulsed IR irradiation. The
photoresponse reported here for vertically aligned graphene (VAG) is much
higher than carbon nanotube (CNT) samples. Our investigation has shown that
such photoresponse arise solely due to bolometric effect, where the
conductivity changes with temperature. The magnitude of the resistance of VAGs
increases by ~ 2 fold for 6 0C increase in temperature. Also the Thermal
Coefficient of Resistance (TCR) in this region is ~11%/K, which is the highest
TCR value reported so far for any carbon nanomaterials.
