title: Gate dependent photo-responses of carbon nanotube field effect phototransistors.
abstract: Gate dependent photoconductivity of carbon nanotube (CNT) field effect phototransistors (FEPs) was systematically investigated in this study. The photo-response comparisons of CNT FEPs with symmetric and asymmetric metal structures connecting to the same CNT revealed that the gate effect contributed to a sensitivity improvement with a lower dark current, a higher photocurrent, and an enhanced photovoltage. A functionalized asymmetric FEP, fabricated by partially doping the CNT utilizing a polyethylene imine (PEI) polymer, verified that FEPs delivered a better performance by using asymmetric structures. A multi-gate FEP, with three pairs of side-gates that can electrostatically dope different sections of a CNT independently, was fabricated to examine the gate structure dependent photo-responses. Experimental measurements showed an unconventional photocurrent improvement that was weakly dependent on the gate location, which was attributed to the unique charge distribution of one-dimensional semiconductors.
authors.affiliation: Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: H Z
authors.initials: HZ
authors.lastname: Chen
authors.forename: N
authors.initials: N
authors.lastname: Xi
authors.forename: K W C
authors.initials: KW
authors.lastname: Lai
authors.forename: L L
authors.initials: LL
authors.lastname: Chen
authors.forename: R G
authors.initials: RG
authors.lastname: Yang
authors.forename: B
authors.initials: B
authors.lastname: Song
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D036103:Nanotechnology / Q000295:instrumentation*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000528:radiation effects*; D010783:Photometry / Q000295:instrumentation*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D014173:Transistors, Electronic
chemical_list: D037742:Nanotubes, Carbon