Lateral energy band profile modulation in tunnel field effect transistors based on gate structure engineering

Abstract

Choosing novel materials and structures is important for enhancing the on-state current in tunnel field-effect transistors (TFETs). In this paper, we reveal that the on-state performance of TFETs is mainly determined by the energy band profile of the channel. According to this interpretation, we present a new concept of energy band profile modulation (BPM) achieved with gate structure engineering. It is believed that this approach can be used to suppress the ambipolar effect. Based on this method, a Si TFET device with a symmetrical tri-material-gate (TMG) structure is proposed. Two-dimensional numerical simulations demonstrated that the special band profile in this device can boost on-state performance, and it also suppresses the off-state current induced by the ambipolar effect. These unique advantages are maintained over a wide range of gate lengths and supply voltages. The BPM concept can serve as a guideline for improving the performance of nanoscale TFET devices.

Si-based hetero-material-gate tunnel field effect transistor: Analytical model and simulation

“…For example, the transfer curve of the HMG TFET with WFgatel = 4.1eV and WFgate2= 4.5eV is almost the same as that of the HMG TFET with WFgatel = 4.3eV and WFgate2 = 4.7eV; the only difference is their V tum-on [12]. Therefore, in our study, WFgatel was set at 4.1eV, and WFgate2 varied.…”

“…Due to the special gate structure, the energy band profile of the HMG TFET is modulated, and a local minimum in conduction band is formed. Previous simulation results showed this band profile modulation (BPM) effect can lead to an abrupt switching behavior and an improved Ion current of TFETs [12]. Based on this design principle, some novel devices were also proposed [13], [14].…”

A Two-Dimensional Analytical Model for Tunnel Field Effect Transistor and Its Applications

“…26,27) According to this principle, the HMG TFET was proposed, and the literature showed that the device had better subthreshold behavior than singlematerial-gate (SMG) TFET. 20,22) The proposed model was extended to the HMG TFET to check the scalability. As presented in Fig.…”

A comparative study of different M(M = Al, Ag, Cu)/FTO bilayer composite films irradiated with nanosecond pulsed laser

“…8a shows, an ohmic contact is produced at the metal-oxide interface, and massive electrons coming from the metal (Al or Ag) layer are concentrated in a very thin region of the FTO near the interface to form an accumulation layer of majority carrier electrons. However, since Cu has a work function of 4.7 eV [46], when Cu and FTO are brought into contact, massive electrons move from the FTO layer to the Cu layer and a barrier layer is formed at the contact interface, as shown in Fig. 8b, resulting in a lower carrier electron concentration at the interface.…”

“…After laser irradiation, the sheet resistances of the Al/FTO, Ag/FTO and Cu/FTO films reduce to 5.8, 6.6 and 7.6 X/sq, respectively. The work function of Al (u = 4.1 eV) and Ag (u = 4.1 eV) are smaller than that of FTO (u = 4.4 eV) [46][47][48]. As a consequence, as Fig.…”