High On-Current Ge-Channel Heterojunction Tunnel Field-Effect Transistor Using Direct Band-to-Band Tunneling

Abstract

The main challenge for tunnel field-effect transistors (TFETs) is achieving high on-current (Ion) and low subthreshold swing (SS) with reasonable ambipolar characteristics. In order to address these challenges, Ge-channel heterostructure TFET with Si source and drain region is proposed, and its electrical characteristics are compared to other TFET structures. From two-dimensional (2-D) device simulation results, it is confirmed that the Si/Ge heterostructure source junction improves Ion and SS characteristics by using the direct band-to-band tunneling current. Furthermore, the proposed structure shows suppressed ambipolar behavior since the Ge/Si heterostructure is used at the drain junction.

Analysis of Current Variation with Work Function Variation in L-Shaped Tunnel-Field Effect Transistor

“…The characteristics of the L-shaped TFET is simulated by the Synopsys Sentaurus TM . The Shockley-Read-Hall (SRH) and dynamic nonlocal BTBT model are used for accurate characteristics [23,24]. The dynamic nonlocal BTBT model is essential to examine lateral-and vertical-BTBT in the L-shaped TFET, since it can dynamically determine and calculate all tunneling paths based on the energy band profile [3,[25][26][27].…”

Methodology to Investigate Impact of Grain Orientation on Threshold Voltage and Current Variability in Tunneling Field-Effect Transistors

“…All of simulations are performed at 300 K The design parameters are summarized in Table 1 are used for a rigorous study. The BTBT parameters for Si tunneling model are calibrated by measured results [23], [24]. In detail, the BTBT model is calibrated with experimental results [28].…”

Optimization of spacer and source/channel junction to improve TFET characteristics

“…The values of design parameters are summarized in Table 1. A Ge is adopted as a body material to improve Ion and S by using narrow bandgap and direct tunneling components [21,22,23,24,25,26,27]. The relative permittivity and thickness of a gate insulator are 3.9 and 2 nm, respectively.…”

“…The source is set as a 10 20 cm -3 -doped p-type while the channel is undoped. Although the use of Ge in the channel could improve Ion of TFETs [27], it delivers large Ioff and the ambipolar effect. It is known that lowering the drain doping concentration can suppress Ioff of Ge TFET effectively [28].…”