Tunneling Field Effect Transistors for Low-Power Switching
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Solution Overview
Problem
Conventional metal oxide semiconductor field effect transistors (MOSFETs) are limited by thermionic emission, resulting in a subthreshold swing greater than 60 millivolts/decade, which restricts their ability to quickly switch between off and on states, thereby limiting their performance.
Innovation Solution
Tunneling field effect transistors (TFETs) utilize tunneling as the primary current transport mechanism across a potential energy barrier, allowing for a lower subthreshold swing and improved performance by using p-type and n-type source/drain materials with a channel material, enabling higher on-current at lower supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional MOSFETs use thermionic emission for current transport, then the device structure is simple and easy to manufacture, but the subthreshold swing is greater than or equal to 60 millivolts/decade, limiting switching performance
Solution Approach 1:
The patent changes the fundamental current transport mechanism from thermionic emission to band-to-band tunneling by modifying the energy band alignment between source and channel materials. This parameter change enables subthreshold swing below 60 mV/decade, improving switching performance while maintaining device functionality
Solution Approach 2:
The patent employs composite material structures including heterojunctions of different semiconductor materials (e.g., InGaAs channel with InAlAs source/drain) to create favorable band alignment for tunneling. These composite structures enable the tunneling mechanism while providing a systematic approach to device fabrication
2Power
If MOSFETs operate at higher supply voltages to achieve higher on-current, then the current drive capability improves, but the power consumption increases
Solution Approach 1:
The patent changes the current transport mechanism to band-to-band tunneling, which provides higher on-current at lower supply voltages compared to thermionic emission. This parameter change directly addresses the trade-off between power consumption and current drive capability, enabling low-power operation
Solution Approach 2:
The patent substitutes the thermionic emission mechanism with quantum mechanical tunneling for current transport. This substitution allows carriers to traverse the barrier through quantum tunneling rather than thermal excitation, achieving higher efficiency and lower power consumption
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
TFETs achieve a lower subthreshold swing compared to conventional MOSFETs, enabling higher on-current at lower supply voltages, making them suitable for low-power devices such as smartphones and medical devices.
Implementation Method 1
TFETs utilize tunneling as the primary current transport mechanism across a potential energy barrier
Implementation Method 2
a gate above the channel material, on the first side face and on the second side face
Data Source
AI summary
Disclosed herein are tunneling field effect transistors (TFETs), and related methods and computing devices. In some embodiments, a TFET may include: a first source/drain material having a p-type conductivity; a second source/drain material having an n-type conductivity; a channel material at least partially between the first source/drain material and the second source/drain material, wherein the channel material has a first side face and a second side face opposite the first side face; and a gate above the channel material, on the first side face, and on the second side face.