Study of the preparation and spectral response of stacked graphene nanoribbon-carbon nanotube-based phototransistors

Narrow graphene nanoribbon-carbon nanotube (GNR-CNT) stacks were prepared by the plasma unzipping of single-wall carbon nanotubes (SWCNT). A mix-and-match method was developed for the fabrication of nanosized devices in a microsized chip, and the optoelectronic properties of highly sensitive back-gated field-effect phototransistors (FETs) based on the GNR-CNT stack were evaluated. The photoresponse of the representative phototransistors improved near the Dirac point voltage for flat and thick long channels, with an ultrahigh spectral response of 10–50 A W−1 using over wavelength measurement at room temperature. The channel current of FETs decreased from 10−11 A to 10−15 A with the decrease in temperature, indicating the semiconducting potential of stacks. Because of the high spectral response of GNR-CNT stacks, they can be used as the optical elements in nanosized photoelectric devices such as phototransistors.