Nanoscale Vacuum Electronic Devices for Low Voltage High Current Density
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Solution Overview
Problem
Existing high-speed electronic devices face challenges in achieving ultrafast and high current density operation at low voltage in room-temperature ambient air, as they often require high electric fields that lead to scattering and conflicting situations in solid-state mediums, while vacuum electronic devices suffer from low emission current and high operating voltage.
Innovation Solution
A nanoscale electronic device structure is developed with a first conducting layer, a second conducting layer, and an insulating layer, where a bias voltage induces a two-dimensional electron system, enabling Coulombic repulsion for thresholdless emission of electrons, which travel ballistically through the air with minimal barrier height, achieving high current density at low voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high electric field is applied across a channel to achieve ballistic transport, then carrier velocity increases, but scattering increases and transport reliability deteriorates
Solution Approach 1:
The patent introduces vacuum as an intermediary medium between the cathode and anode, replacing the solid-state channel. This vacuum gap allows electrons to travel ballistically without scattering, as there are no lattice vibrations or impurities to cause scattering events. The vacuum acts as a perfect mediator that enables high-speed transport while maintaining reliability.
Solution Approach 2:
The patent changes the fundamental parameter of the transport medium from solid-state to vacuum. By modifying the physical state of the medium from condensed matter to vacuum, the scattering mechanisms inherent in solid-state are eliminated, allowing electrons to maintain high velocity without scattering.
2Reliability
If vacuum is used as the medium for electron transport, then ballistic transport is achieved, but emission current decreases and operating voltage increases
Solution Approach 1:
The patent changes the emission mechanism parameter from thermal field emission to Schottky emission by controlling the vacuum gap distance and applying moderate electric fields. This parameter change enables significant emission current at low voltages. Additionally, the nanoscale dimensions of the vacuum gap quantize the electron states, enhancing the emission current density.
Solution Approach 2:
The patent transitions from three-dimensional bulk emission to two-dimensional surface emission at the vacuum interface. This dimensional change increases the effective emission area and current density, as electrons are emitted from the surface states at the vacuum-semiconductor interface rather than from bulk material.
3Speed
If conventional vacuum electronic devices are used, then electron transport is achieved, but operating voltage is high and current density is low
Solution Approach 1:
The patent segments the vacuum gap into quantized energy levels by reducing the gap distance to nanoscale dimensions. This segmentation of the continuous vacuum space into discrete quantum states enables low-voltage operation, as electrons can transition between quantized levels with small energy inputs, reducing the required operating voltage while maintaining high-speed transport.
Solution Approach 2:
The patent changes the vacuum gap distance parameter from micrometer-scale to nanometer-scale dimensions. This parameter change fundamentally alters the electronic structure of the vacuum gap, creating quantized states that enable low-voltage operation. The nanoscale gap also increases the electric field strength for a given voltage, enhancing electron emission and current density.
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 device achieves ultrafast (fs transit time) and high current density (˜105 A/cm2) operation at low voltage (˜1 V) with virtually thresholdless electron emission, surpassing conventional emission models and demonstrating Child-Langmuir's space-charge-limited current flow, indicating efficient ballistic transport.
Implementation Method 1
electrons from the two dimensional electron system are emitted from the at least one side wall side wall as a result of Coulombic repulsion
Implementation Method 2
electrons from the two dimensional electron system are emitted from the at least one side wall side wall as a result of Coulombic repulsion and travel in air from the one of the first conducting layer and the second conducting layer to the other
Data Source
AI summary
An electronic device including a first conducting layer, a second conducting layer, and an insulating layer provided between the conducting layers. At least one side wall extends from the first conducting layer to the second conducting layer and includes at least a portion of the first conducting layer, the second conducting layer and the insulating layer. A bias voltage is applied between the first and second conducting layers, wherein responsive to the bias voltage, a two dimensional electron system is induced at least in one of the first conducting layer and the second conducting layer, and wherein electrons from the two dimensional electron system are emitted from the side wall side wall as a result of Coulombic repulsion and travel in air from the one of the first conducting layer and the second conducting layer to the other of the first conducting layer and the second conducting layer.