Figure 3. Temporal characteristics and ultra-broadband photoresponse.

(a,b) Temporal photocurrent response of the SWNT–graphene hybrid photodetector, indicating a rise time and a fall time on the order of ∼100 μs. The illumination power is 440 μW and the laser wavelength is 650 nm. (c) External quantum efficiency as a function of illumination power at 650 nm. (d) Responsivities as a function of the optical power for different illumination wavelengths (405, 532, 650, 980 and 1,550 nm). (e) Comparison of responsivities measured from devices using purified metallic- and (6,5) chirality-enriched SWNTs. It is shown that the responsivity of the metallic tube-based devices is ∼5% of that of (6,5) chirality tube-based devices.