Dependence of electrical characteristics of TDTFT on asymmetry of tunneling dielectric film

We examined the effect of asymmetry of tunneling dielectric film formed on the drain or source electrode on performance of TFT. We fabricated three kinds of TDTFTs and a conventional TFT. For the experiment which clarifies the asymmetry, the tunneling dielectric film was formed on one electrode, and the electrical characteristics were measured by reversing polarity of the electrode. The dielectric film is SiN_x(4.07 nm)/SiO₂(2.67 nm) composite one. Both the on/off ratio and the subthreshold characteristics of the sample where the positive voltage was applied to the electrode with SiN_x/SiO₂ film are superior to the reverse condition of the voltage application. Moreover, for the positive voltage application to the electrode, the performance of the TDTFT is also superior to that of conv. TFT. These results strongly indicate that the asymmetry of SiN_x film formation influences the performance of TFT.