Graphene Device Physical Gap Reduces Off-Current
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Solution Overview
Problem
Graphene devices suffer from a high off-current due to their zero band gap, which compromises the high electron mobility and results in a low on/off current ratio, and existing methods to introduce a band gap often reduce electron mobility by causing additional defects.
Innovation Solution
A graphene device structure is introduced with a physical gap between the graphene channel and the source/drain electrodes, utilizing a high-K spacer to reduce off-current and increase on-current by forming a fringing field and breaking down the substrate region, thereby maintaining high electron mobility without opening a band gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a band gap is opened in graphene using nanoribbons, uniaxial strain, bilayer graphene, or doping techniques, then the off-current is reduced, but additional defects are caused that significantly reduce electron mobility
Solution Approach 1:
The invention introduces a physical gap that segments the continuous graphene channel into two parts separated by the gap. This segmentation creates a discontinuity that blocks off-current flow while preserving the high mobility of electrons within each graphene segment. The gap acts as a spatial divider that eliminates the harmful off-current path without introducing defects into the graphene lattice itself.
Solution Approach 2:
The physical gap serves as an intermediary element between the source/drain electrodes and the graphene channel. Instead of modifying the graphene to open a band gap, the invention introduces this intermediate gap structure that mediates the electrical connection, allowing control of off-current while leaving the graphene's intrinsic high mobility intact.
2Object-generated harmful factors
If a physical gap is introduced between source/drain electrode and graphene channel, then off-current is reduced and on/off current ratio is increased, but device complexity increases due to additional high-K spacer structure
Solution Approach 1:
The high-K spacer acts as an intermediary dielectric material that fills the physical gap between the source/drain electrode and the graphene channel. This intermediary structure enables the physical gap to function effectively by providing electrical isolation and controlling the electric field distribution, thereby reducing off-current while managing the added structural complexity through a well-defined dielectric component.
Solution Approach 2:
The invention changes the dielectric parameter by introducing a high-K spacer material with high dielectric constant into the physical gap. This parameter change optimizes the electrical characteristics of the gap region, enhancing the off-current suppression capability while maintaining a manageable device structure through controlled dielectric properties.
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 significantly enhances the on/off current ratio to 10^7 or higher, while maintaining high electron mobility, making graphene suitable for digital devices by reducing off-current and increasing on-current through the physical gap and fringing field mechanism.
Implementation Method 1
when a voltage higher than the threshold voltage is applied to the gate, a fringing field will be formed through the high-K spacer, so that the energy band of the substrate region under the high K-spacer can be inversed and the effective length of the physical gap can be reduced to increase the on-current by a breakdown occurring in the substrate region corresponding to the physical gap
Implementation Method 2
any one or more of the source and the drain are spaced apart from the graphene channel by a physical gap... the off-current will be reduced due to the physical gap
Data Source
AI summary
Disclosed herein is a graphene device having a structure in which a physical gap is provided so that the off-state current of the graphene device can be significantly reduced without having to form a band gap in graphene, and thus the on/off current ratio of the graphene device can be significantly increased while the high electron mobility of graphene is maintained.