Gate Tunable Tunnel Diode Using Graphene Electrode
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Solution Overview
Problem
Conventional diodes, particularly tunnel diodes, face limitations in modulating their threshold voltage and achieving asymmetric current output due to screening effects from bulk materials, leading to restricted operational frequency and speed.
Innovation Solution
The development of a gate tunable metal-insulator-metal (MIM) tunnel diode using a graphene electrode, where the workfunction is modulated by an external electric field, allowing for modulation of the threshold voltage and facilitating Fowler-Nordheim tunneling to achieve asymmetric current behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional tunnel diodes are used, then current flow is achieved, but threshold voltage modulation is limited due to screening effects from bulk materials
Solution Approach 1:
The patent extracts the diode junction from bulk semiconductor material and places it in a suspended configuration where the active region is free from substrate screening effects. This allows the electric field to penetrate through the entire device structure, enabling effective threshold voltage modulation that would be blocked in conventional bulk materials.
Solution Approach 2:
The patent employs a composite structure combining graphene electrodes with tunnel dielectric layers, creating a metal-insulator-metal (MIM) tunnel diode. This composite material approach allows the device to achieve both high conductivity from graphene and effective tunneling from the dielectric, while the suspended configuration prevents bulk material screening effects.
2Speed
If conventional diodes are used, then current flow is achieved, but operational frequency and speed are restricted
Solution Approach 1:
By extracting the diode structure from bulk semiconductor and implementing it in a suspended configuration, the patent eliminates the screening effects that limit carrier mobility and response time in conventional materials. This enables faster operational frequencies while maintaining current flow capability.
Solution Approach 2:
The patent replaces conventional semiconductor physics mechanisms with quantum mechanical tunneling through the dielectric layer. This substitution enables ultra-fast operation since tunneling occurs on femtosecond timescales, bypassing the slower carrier transport mechanisms that limit conventional diode speed.
3Ease of operation
If gate electrode is embedded in gate dielectric, then electrical control is achieved, but device complexity increases
Solution Approach 1:
The patent segments the device into distinct functional layers: gate electrode, gate dielectric, suspended tunnel dielectric, and electrodes. This segmentation allows independent optimization of each component and simplifies the fabrication process by enabling separate deposition and patterning steps for each layer.
Solution Approach 2:
The patent transitions from planar device architecture to a three-dimensional suspended structure. The tunnel dielectric is positioned in the space above the gate dielectric, creating a vertical electric field configuration that enhances control efficiency while maintaining a compact footprint.
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 fast operation with large output current asymmetry and electric field modulation of the threshold voltage, surpassing the speed limitations of conventional diodes, with the potential for high-frequency applications.
Implementation Method 1
the workfunction is modulated by an external electric field, allowing for modulation of the threshold voltage
Implementation Method 2
facilitating Fowler-Nordheim tunneling to achieve asymmetric current behavior
Data Source
AI summary
A gate tunable diode is provided. The gate tunable diode includes a gate dielectric formed on a gate electrode and a graphene electrode formed on the gate dielectric. Also, the gate tunable diode includes a tunnel dielectric formed on the graphene electrode and a tunnel electrode formed on the tunnel dielectric.