In this paper, a dopingless fin-shaped SiGe channel TFET (DF-TFET) is proposed and studied. To form a high-efficiency dopingless line tunneling junction, a fin-shaped SiGe channel and a gate/source overlap are induced. Through these methods, the DF-TFET with high on-state current, switching ratio of 12 orders of magnitude and no obvious ambipolar effect can be obtained. High κ material stack gate dielectric is induced to improve the off-state leakage, interface characteristics and the reliability of DF-TFET. Moreover, by using the dopingless channel and fin structure, the difficulties of doping process and asymmetric gate overlap formation can be resolved. As a result, the structure of DF-TFET can possess good manufacture applicability and remarkably reduce footprint. The physical mechanism of device and the effect of parameters on performance are studied in this work. Finally, on-state current (I_ON) of 58.8 μA/μm, minimum subthreshold swing of 2.8 mV/dec (SS_min), average subthreshold swing (SS_avg) of 18.2 mV/dec can be obtained. With improved capacitance characteristics, cutoff frequency of 5.04 GHz and gain bandwidth product of 1.29 GHz can be obtained. With improved performance and robustness, DF-TFET can be a very attractive candidate for ultra-low-power applications.

Label-free biomolecular sensors have been widely studied due to their simple operation. L-shaped tunneling field-effect transistors (LTFETs) are used in biosensors due to their low subthreshold swing, off-state current, and power consumption. In a dielectric-modulated LTFET (DM-LTFET), a cavity is trenched under the gate electrode in the vertical direction and filled with biomolecules to realize the function of the sensor. A 2D simulator was utilized to study the sensitivity of a DM-LTFET sensor. The simulation results show that the current sensitivity of the proposed structure could be as high as 2321, the threshold voltage sensitivity could reach 0.4, and the subthreshold swing sensitivity could reach 0.7. This shows that the DM-LTFET sensor is suitable for a high-sensitivity, low-power-consumption sensor field.

By adopting the first-principles plane wave pseudopotential method based on density functional theory, the electronic structure properties of single-layer MoS₂ (molybdenum disulfide) crystals under biaxial strain are studied. The calculation results in this paper show that when a small strain is applied to a single-layer MoS₂, its band structure changes from a direct band gap to an indirect band gap. As the strain increases, the energy band still maintains the characteristics of the indirect band gap, and the band gap shows a linear downward trend. Through further analysis of the density of states, sub-orbital density of states, thermodynamic parameters and Raman spectroscopy, it revealed the variation of single-layer MoS₂ with strain. This provides a theoretical basis for realizing the strain regulation of MoS₂.

In order to detect biomolecules, a biosensor based on a dielectric-modulated stacked source trench gate tunnel field effect transistor (DM-SSTGTFET) is proposed. The stacked source structure can simultaneously make the on-state current higher and the off-state current lower. The trench gate structure will increase the tunneling area and tunneling probability. Technology computer-aided design (TCAD) is used for the sensitivity study of the proposed structured biosensor. The results show that the current sensitivity of the DM-SSTGTFET biosensor can be as high as 10⁸, the threshold voltage sensitivity can reach 0.46 V and the subthreshold swing sensitivity can reach 0.8. As a result of its high sensitivity and low power consumption, the proposed biosensor has highly promising prospects.

In this paper, an L-shaped tunneling field effect transistor (LTFET) with ferroelectric gate oxide layer (Si: HfO₂) is proposed. The electric characteristic of NC-LTFET is analyzed using Synopsys Sentaurus TCAD. Compared with the conventional LTFET, a steeper subthreshold swing (SS = 18.4 mV/dec) of NC-LTFET is obtained by the mechanism of line tunneling at low gate voltage instead of diagonal tunneling, which is caused by the non-uniform voltage across the gate oxide layer. In addition, we report the polarization gradient effect in a negative capacitance TFET for the first time. It is noted that the polarization gradient effect should not be ignored in TFET. When the polarization gradient parameter g grows larger, the dominant tunneling mechanism that affects the SS is the diagonal tunneling. The on-state current (I_on) and SS of NC-LTFET become worse.

Tunneling field-effect transistors (TFETS) can reduce the subthreshold swing (SS) to below 60 mV/decade due to their conduction mechanism with band-to-band tunneling (BTBT), thereby reducing power consumption. T-shaped gate tunneling field-effect transistors (TGTFET) adapt double source and T-shaped gates to enhance the on-state current and to generate the tunneling probability. In this paper, TGTFET subjected to heavy-ion irradiation is studied by technology computer-aided design (TCAD) simulation for the first time. The results show that as the drain bias and linear energy transfer (LET) increase, the transient current and collected charge also increase. When LET = 100 MeV·cm²/mg and V_d = 0.5 V, the transient current of TGTFET is as high as 10.63 mA, which is much larger than the on-state current. This means that TGTFET is more sensitive to single-event effect (SEE) than FDSOI. By simulating a heavy-ion strike on different locations in TGTFET, the tunneling junction is the most sensitive region of SEE. This provides guidance for future research on the antiradiation application of TFET-based devices.