Graphene FET Separated Junction Contacts Off-State Leakage
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Solution Overview
Problem
Graphene-based devices face challenges in maintaining low current in the off-state due to high current leakage between the source and drain, making it difficult to switch between on and off states effectively.
Innovation Solution
A graphene device with separated junction contact layers, where the first and second junction contact layers are doped to have the same conduction type and are electrically separated by a trench filled with an insulating material, along with a gate electrode and insulating films, to control the flow of carriers and maintain low current in the off-state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphene-based devices use conventional contact structures, then device simplicity is maintained, but high current leakage occurs between source and drain in off-state
Solution Approach 1:
The contact structure is segmented into separate first and second junction contact layers that are electrically isolated from each other. This segmentation prevents direct current leakage paths between source and drain while maintaining necessary electrical connections to the graphene channel layer, thereby improving off-current characteristics without excessive complexity
Solution Approach 2:
An insulating layer is introduced as an intermediary between the first and second junction contact layers. This insulating layer acts as a mediator that blocks current leakage while allowing both contact layers to independently interface with the graphene channel layer, resolving the contradiction between reliability and complexity
2Reliability
If junction contact layers are doped to have the same conduction type and electrically separated, then off-state current is reduced, but manufacturing complexity increases
Solution Approach 1:
The first and second junction contact layers are doped to have the same conduction type in advance, before device operation. This preliminary doping action establishes the desired electrical characteristics that prevent current leakage in off-state, while the doping process itself uses conventional techniques that do not significantly increase manufacturing complexity
Solution Approach 2:
The conduction type parameter of the junction contact layers is changed through controlled doping processes. By adjusting doping parameters to create identical conduction types in both contact layers, the device achieves improved current control while using standard semiconductor manufacturing parameters and processes
3Reliability
If a separation film with trench is used to electrically separate junction contact layers, then off-current characteristic is improved, but device structure becomes more complex
Solution Approach 1:
The separation structure is segmented into a trench component and an insulating film component. The trench provides physical division while the insulating film provides electrical isolation, achieving effective electrical separation through segmented architecture that manages complexity by dividing functions into distinct structural elements
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
The solution enables efficient switching between on and off states by limiting carrier movement between the graphene channel layer and the junction contact layers, thereby maintaining low current in the off-state and improving the off-current characteristic.
Implementation Method 1
a gate electrode for applying an electric field to the graphene channel layer
Implementation Method 2
a separation film disposed between the first junction contact layer and the second junction contact layer in order to electrically separate the first junction contact layer and the second junction contact layer from each other
Implementation Method 3
The first and second junction contact layers may be doped to have the same conduction type. The substrate may be doped to have an electrically opposite conduction type to the conduction type of the first and second junction contact layers
Data Source
AI summary
A graphene device including separated junction contacts and a method of manufacturing the same are disclosed. The graphene device is a field effect transistor (FET) in which graphene is used as a channel. A source electrode and a drain electrode do not directly contact the graphene channel, and junction contacts formed by doping semiconductor are separately disposed between the graphene channel and the source electrode and between the graphene channel and the drain electrode. Therefore, in an off state where a voltage is not applied to a gate electrode, due to a barrier between the graphene channel and the junction contacts, carriers may not move. As a result, the graphene device may have low current in the off state.