Synthesized multiwall MoS₂ nanotube and nanoribbon field-effect transistors

We report on the fabrication and characterization of synthesized multiwall MoS₂ nanotube (NT) and nanoribbon (NR) field-effect transistors (FETs). The MoS₂ NTs and NRs were grown by chemical transport, using iodine as a transport agent. Raman spectroscopy confirms the material as unambiguously MoS₂ in NT, NR, and flake forms. Transmission electron microscopy was used to observe cross sections of the devices after electrical measurements and these were used in the interpretation of the electrical measurements, allowing the estimation of the current density. The NT and NR FETs demonstrate n-type behavior, with ON/OFF current ratios exceeding 10³, and with current densities of 1.02 μA/μm and 0.79 μA/μm at V_DS = 0.3 V and V_BG = 1 V, respectively. Photocurrent measurements conducted on a MoS₂ NT FET revealed short-circuit photocurrent of tens of nanoamps under an excitation optical power of 78 $μ$W and 488 nm wavelength, which corresponds to a responsivity of 460 $μ$A/W. A long channel transistor model was used to model the common-source characteristics of MoS₂ NT and NR FETs and was shown to be consistent with the measured data.