TCAD Simulation of the Doping-Less TFET with Ge/SiGe/Si Hetero-Junction and Hetero-Gate Dielectric for the Enhancement of Device Performance

Abstract

The device structure of DLTFET is optimized by the Silvaco TCAD software to solve the problems of lower on-state current and larger miller capacitance of traditional doping-less tunneling field effect transistors (DLTFETs), and the performance can be greatly improved. Different from the traditional DLTFETs, the source region and pocket region of the doping-less TFET with the Ge/SiGe/Si hetero-junction and hetero-gate dielectric (H-DLTFET), respectively, use the narrow band-gap semiconductor Ge and SiGe materials, and the channel and drain region both use the silicon material. The H-DLTFET device use the Ge/SiGe hetero-junction engineering to decrease the tunneling barrier width, increase the band-to-band tunneling current, and obtain the higher current switching ratio and ultra-low sub-threshold swing (SS). Besides, the gate dielectric under auxiliary gate uses the low-k dielectric SiO2 material, which can effectively reduce the miller capacitance and improve the capacitance and frequency characteristics. The on-state current, switching ratio, trans-conductance, output current, and output conductance values of H-DLTFET can be increased by two, two, one, one, and one order of magnitude when compared with the DLTFET, respectively. Meanwhile, the point SS and average SS, respectively, decrease from 13 mV/Dec and 31.6 mV/Dec to 5 mV/Dec and 14.3 mV/Dec, and the gate-drain capacitance decrease from 0.99 fF/μm to 0.1 fF/μm. Besides, the cutoff frequency and gain bandwidth product of H-DLTFET are much larger than that of DLTFET, which can be explained by the excellent DC characteristics. The above simulation results show that the H-DLTFET has the better frequency characteristics, so it is more suitable for applications of ultra-low-power integrated circuits.

A Novel L-Gate InGaAs/GaAsSb TFET with Improved Performance and Suppressed Ambipolar Effect

“…Figure 12c shows the characteristic curves of f T and GBW versus Vg at V d = 0.5 V. Benefiting from structural advantages, such as L-shaped channel and source, the HJTFET obtains the most outstanding frequency characteristics compared with others [21][22][23][24][25][26][27][28][29][30][31][32]. As shown in Figure 12b, the f T and GBP of the HJTFET reached the maximum values of 68.3 GHz and 7.3 GHz under the condition of V d = 0.5 V, respectively.…”

“…To further improve the ON-state current, multimaterial heterojunction engineering is applied to improve the band-to-band tunneling rate [20]. Compared with conventional homojunction TFET, research shows that HJTFETs have superior performances, such as Si/SiGe heterojunction [21][22][23][24], SiGeSn/GeSn heterojunction [25], and III-V heterojunction [26][27][28][29][30][31][32]. By selecting appropriate materials to form heterojunction, on the one hand, the height and thickness of the tunneling barrier can be effectively reduced.…”

The Structural Performance of a Novel Double‐Stacked Heterogeneous Gate Heterojunction Tunneling Field‐Effect Transistor

“…[2][3][4][5] To solve the problems of MOSFET, a novel semiconductor device structure has been developed to replace MOSFET, including a novel conduction mechanism. [6][7][8][9] Owing to that the major operation mechanism of tunneling field-effect transistor (TFETs) is band-to-band tunneling (BTBT), TFETs can break the limitation of 60 mV dec À1 SS compared to the traditional MOSFET. BTBT refers to the movement that electrons tunnel from the valence band of source to the conduction band of channel when an electric field is applied at the location of the device band bending.…”