Proposal and examination of new type of TFT with tunneling dielectric film at both ends of channel fabrication area

Abstract

SUMMARYAn important aspect of a thin-film transistor (TFT) is reducing the current flowing between the source and drain when the gate is off. In this research, we proposed a new TFT, the tunneling dielectric TFT (TDTFT), that has a thin dielectric film on both ends of the channel region, and studied its operation through simulations. We calculated the drain current (I off ) when the gate is off, the drain currentdrain voltage characteristic, and the transconductance in the TDTFT. When the thin dielectric film is a 0.5-nm-thick TiO 2 film, I off of the TDTFT is about six digits less than that of a conventional TFT. We also studied the double silicon on insulator (DSOI) structure which improves the drive power of the TFT even for a thin Si film. When a TDTFT is fabricated on DSOI, simple calculations showed that the on-off ratio was several times better than that of a conventional TFT.

Fabrication of tunneling dielectric thin-film transistor with very thin SiNx films onto source and drain

“…The reason of these phenomena is due to the tunneling resistance at the contact area which has a close relationship with the thickness of SiN x film. It is found from the simple calculation [5,6] that the tunneling resistance is larger than the channel resistance in the present case. The further thinning of the SiN x film down to 0.5 nm and the material, such as TiO 2 , with the barrier height lower than SiN x will improve the electric characteristics of the TDTFT.…”

“…Although the trial to decrease those defects has been performed by enlarging the grain size [3] or terminating the dangling bonds by hydrogens [4], it is difficult to remove those defects completely. To solve this problem, a new transistor named as Tunneling Dielectric TFT (TDTFT) [5,6] was designed and proposed. The TDTFT employs nonlinear resistors connected in series to the source and drain electrodes.…”

Review—Technology Trends of Poly-Si TFTs from the Viewpoints of Crystallization and Device Performance

“…LPX will apply to a promising crystallization apparatus at low-temperature in future by optimizing the light source. 25,29,[57][58][59] .-Although highperformance TFTs with a high carrier mobility and low leakage current utilizing the large single-crystalline grains have been intensively researched, such devices have not been successfully introduced as a mass-production technology. 60 The fatal flaw of this technology is that the grains lack the same shape and crystallinity in the large-area substrate.…”

“…On the other hand, the requirements for the devices include large drivability, which improves the signal propagation, and a low leakage currents, which improve the switching characteristics. The double gate TFT, 24 tunnel-dielectric TFT (TDTFT), 25 an artificial retina using the TFT, 26 Fin-TFT as one of the three-dimensional TFTs 27 and IPS LCD by selectively enlarging laser crystallization (SELAX) 28 have been developed. However, the hump effect has been reported to occur in multiple-gate TFTs, and overcoming this drawback is important.…”

“…33 We applied the double barriers to a conventional TFT, resulting in the tunnel-dielectric TFT (TDTFT). 25 The advantage of this device is its small subthreshold swing.…”