Abstract
This paper presents a germanium-around-source gate-all-around tunnelling field-effect transistor (GAS GAA TFET). The electrical characteristics of the device were studied and compared with those of silicon gate-all-around and germanium-based-source gate-all-around tunnel field-effect transistors. Furthermore, the electrical characteristics were optimised using Synopsys Sentaurus technology computer-aided design (TCAD). The GAS GAA TFET contains a combination of around-source germanium and silicon, which have different bandgaps. With an increase in the gate-source voltage, band-to-band tunnelling (BTBT) in silicon rapidly approached saturation since germanium has a higher BTBT probability than silicon. At this moment, germanium could still supply current increment, resulting in a steady and steep average subthreshold swing and a higher ON-state current. The GAS GAA TFET was optimised through work function and drain overlapping engineering. The optimised GAS GAA TFET exhibited a high ON-state current () (11.9 A), a low OFF-state current () (A), and a low and steady (57.29 mV/decade), with the OFF-state current increasing by times. The GAS GAA TFET has high potential for use in low-power applications.
Highlights
Owing to rapid advances in semiconductor device technology, fifth-generation communication devices, wearable devices, Internet of Things, and numerous information technology devices have been developed
Researchers have been studying devices with a steep subthreshold swing (SS). Owing to their conduction mechanisms, such as impact ionization and band-to-band tunnelling (BTBT), differing from that of conventional metal-oxide-semiconductor field-effect transistors (MOSFETs), the ionization MOS (I-MOS), which is based on impact ionization, and tunnelling field-effect transistor (TFET), which is based on BTBT, can achieve the SS, lower than 60 mV/decade
TFETs provide a steeper SS, a lower OFF-state current (IOFF) and a lower supply voltage compared to conventional MOSFETs [10,11,12,13,14,15] and are suitable for low-power applications
Summary
Owing to rapid advances in semiconductor device technology, fifth-generation communication devices, wearable devices, Internet of Things, and numerous information technology devices have been developed. Researchers have been studying devices with a steep SS Owing to their conduction mechanisms, such as impact ionization and band-to-band tunnelling (BTBT), differing from that of conventional MOSFETs, the ionization MOS (I-MOS), which is based on impact ionization, and tunnelling field-effect transistor (TFET), which is based on BTBT, can achieve the SS, lower than 60 mV/decade. SSAVG dramatically increases as Vgs increases, resulting in SSAVG and SSMIN differing considerably and SSAVG becoming unsteady This is a disadvantage of conventional Si TFETs. Owing to the large bandgap and carrier mass of the silicon material, conventional Si TFETs have another disadvantage: A low ON-state current (ION) [21,22,23]. The characteristics of the device were investigated in detail to evaluate its capability for low-power applications
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