Tunnel FET Broken-Gap Heterostructure Band Alignment
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Solution Overview
Problem
The scaling limitations of silicon-based CMOS technology in field-effect transistors hinder the development of energy-efficient and high-speed semiconductor devices, necessitating alternative technologies that can reduce power dissipation and increase compactness.
Innovation Solution
The fabrication of tunnel field-effect transistors using a drain, source, and tunnel barrier made from semiconductor materials with specific band gaps, where the tunnel barrier's larger band gap bends under external bias to align energy bands, facilitating efficient tunneling and controlling the tunneling window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If silicon-based CMOS technology is scaled down to reduce feature sizes, then device compactness is improved, but physical and electrical limitations prevent further scaling
Solution Approach 1:
The patent changes the fundamental operating principle of the transistor from drift-diffusion current (CMOS) to quantum mechanical tunneling current. By using a tunnel barrier with specific band gap properties and creating a broken-gap alignment between source and drain materials, the device achieves current flow through direct band-to-band tunneling, enabling operation at scaled dimensions where traditional CMOS fails
Solution Approach 2:
The patent employs composite material structure with at least three different semiconductor materials having different band gaps: source material with first band gap, tunnel barrier material with second band gap, and drain material with third band gap. This composite structure enables the broken-gap alignment necessary for efficient tunneling while maintaining device functionality
2Power
If traditional CMOS field-effect transistors are used, then device performance is maintained, but power dissipation is high
Solution Approach 1:
The patent replaces the classical drift-diffusion transport mechanism with quantum mechanical tunneling. By utilizing the quantum tunneling effect through a carefully engineered barrier with broken-gap alignment, the device achieves lower off-state current and reduced power dissipation compared to thermal carrier generation in traditional CMOS
Solution Approach 2:
The patent changes the current transport mechanism from thermal excitation to quantum tunneling by engineering the band structure. The broken-gap alignment creates direct overlap between valence band of source and conduction band of drain, enabling efficient carrier transport with lower energy dissipation
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
This approach enables the creation of energy-efficient, high-speed tunnel field-effect transistors with improved switching performance and reduced power consumption, overcoming the limitations of traditional CMOS technology.
Implementation Method 1
a tunnel field-effect transistor, which is based on ultrathin films and band-to-band tunneling in which a valence band electron tunnels across the band gap to the conduction band without the involvement of traps
Implementation Method 2
The third band gap is configured to bend under an external bias to assist in aligning a first energy band of the first semiconductor material with a second energy band of the second semiconductor material
Data Source
AI summary
Device structures, fabrication methods, and design structures for tunnel field-effect transistors. A drain comprised of a first semiconductor material having a first band gap and a source comprised of a second semiconductor material having a second band gap are formed. A tunnel barrier is formed between the source and the drain. The second semiconductor material exhibits a broken-gap energy band alignment with the first semiconductor material. The tunnel barrier is comprised of a third semiconductor material with a third band gap larger than the first band gap and larger than the second band gap. The third band gap is configured to bend under an external bias to assist in aligning a first energy band of the first semiconductor material with a second energy band of the second semiconductor material.