Graphene Charge Sensing Around the Neutrality Point
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Solution Overview
Problem
Existing electronic devices for charge sensing, particularly those using 2-dimensional materials like graphene, face limitations in sensitivity and dynamic range due to quantum capacitance effects, and require operation around the charge neutrality point, where sensitivity is minimal.
Innovation Solution
An electronic apparatus with a gate electrode structure, dielectric structure, and a 2-dimensional charge sensing layer that applies a gate voltage to tune quantum capacitance, allowing active control over sensitivity and dynamic range by operating around the charge neutrality point and adjusting the gate voltage's magnitude, frequency, and phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the capacitance is minimized to maximize output voltage for high sensitivity, then sensitivity is improved, but the dynamic range is reduced
Solution Approach 1:
The patent applies a time-varying gate voltage with specific frequency and phase characteristics to dynamically modulate the quantum capacitance of the 2D material. This dynamic control allows the system to switch between high-sensitivity mode (when quantum capacitance is minimized) and high dynamic range mode (when quantum capacitance is increased), resolving the contradiction between these two opposing requirements.
Solution Approach 2:
The patent changes the operating parameters of the 2D material by applying a gate voltage with specific frequency and phase relative to the modulating signal. This parameter change modulates the carrier density in the 2D material, thereby controlling the quantum capacitance value to achieve the desired balance between sensitivity and dynamic range for different operating conditions.
2Measurement precision
If the dielectric thickness is increased to minimize capacitance and maximize output voltage, then sensitivity is improved, but the device complexity and parasitic capacitances increase
Solution Approach 1:
Instead of changing the physical dimension (dielectric thickness), the patent changes the electrical parameter (quantum capacitance) by applying a modulating gate voltage to the 2D material. This allows capacitance control without increasing dielectric thickness, thereby avoiding increased parasitic capacitances and maintaining high sensitivity while reducing device complexity.
3Adaptability or versatility
If the quantum capacitance is increased to enhance dynamic range, then adaptability is improved, but the output voltage and sensitivity are reduced
Solution Approach 1:
The patent uses dynamic modulation of the gate voltage at specific frequencies and phases to control the quantum capacitance in real-time. This allows the system to adapt between high dynamic range operation (with higher quantum capacitance) and high sensitivity operation (with lower quantum capacitance), resolving the contradiction between these two performance metrics.
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
Enables high sensitivity and dynamic range applications by actively controlling the electronic device's performance, enhancing output voltage and capacitance, and allowing for high sensitivity and dynamic range operations depending on the applied gate voltage.
Implementation Method 1
the charge sensing structure shows a quantum capacitance Cq in series with said gate capacitance Cg resulting in a total capacitance Ctot between the charge sensing structure and the gate electrode structure
Implementation Method 2
a gate voltage selected to, both: make the electronic device operate around the charge neutrality point; and tune the quantum capacitance to modify the sensitivity and dynamic range of the electronic device
Implementation Method 3
a charge sensing structure comprising at least one 2-dimensional charge sensing layer configured to sense electrical charges induced by an external physical quantity
Implementation Method 4
configured to sense electrical charges induced by an external physical quantity
Data Source
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AI summary
The present invention relates to a system comprising an electronic apparatus which comprises: - an electronic device comprising: - a gate electrode (G, BE); - a dielectric (D) arranged over the gate electrode (G, BE); and - a charge sensing structure (CE) with a 2-dimensional charge sensing layer to provide a gate capacitance (Cg) between the charge sensing structure (CE) and the gate electrode structure (G, BE) and a quantum capacitance (Cq) resulting in a total capacitance (Ctot); - a voltage detector to detect an output voltage (Vo) stored in the total capacitance (Ctot). The system further comprises means to apply a gate voltage (Vg) to the gate electrode structure (G, BE) selected to: - make the device operate around most sensitive point of fermi level of the charge sensing structure (CE); and - tune the quantum capacitance (Cq). The present invention also relates to an electronic apparatus adapted to allow the tuning of its quantum capacitance.