Photoelectric Characterization of a Single Layer of CNTs using CAFM

Detailed investigations for the photoelectric characteristics of a single-layer of carbon nanotubes (CNTs) have been performed using a conductive mode atomic force microscope (CAFM). The diluted CNTs were drop-casted on a SiO
2
/n-Si substrate followed by annealing in N
2
ambient for 2 hours at 70°C. Individual CNTs were identified using the AC imaging mode of atomic force microscope (AFM). Subsequently, the electrical measurements were performed using CAFM with an Au-coated tip placed directly on the CNTs. A lower turn-on voltage is observed for the shorter wavelength of light illuminated on the CNTs, compared to that of a long light wavelength, indicating higher energy electrons are excited to the conduction band of the CNT.