ExB Drift Thermoelectric Generator Using Depletion Mode
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Solution Overview
Problem
Existing thermoelectric devices face limitations in power generation due to the cancellation of net current from equal concentrations of positively and negatively charged particles in a medium with infinite mobility, and are restricted by material properties and heat flow directions in devices with finite mobility.
Innovation Solution
The ExB drift thermoelectric energy generation device leverages the differences in mobility, effective mass, and charge of electrons and holes by optimizing the magnetic field, electric field, and semiconductor layer geometry to produce a net output current and power, using materials with appropriate band gaps and doping levels to maintain the semiconductor in depletion mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a medium with infinite mobility is used, then particles follow clear cycloid paths, but the net output current is zero due to cancellation from equal concentrations of positive and negative carriers
Solution Approach 1:
The patent changes the mobility parameter from infinite to finite, which fundamentally alters the carrier behavior. With finite mobility, the cycloid paths are modified and the cancellation effect is reduced, allowing a net output current to be generated while maintaining predictable carrier paths
2Power
If materials with high carrier concentration are used, then the material has good conductivity, but the electric field is canceled by space charges and the semiconductor leaves depletion mode
Solution Approach 1:
The patent optimizes the carrier concentration parameter to maintain depletion mode operation. By controlling doping levels and selecting materials with appropriate band gaps, the device operates in depletion mode where the electric field is not canceled by space charges, enabling effective ExB drift while maintaining good conductivity
3Power
If the semiconductor layer is made thick to accommodate carrier cycloid paths, then ExB drift is maintained, but device size and complexity increase
Solution Approach 1:
The patent optimizes the semiconductor layer thickness parameter to match the cycloid path dimensions. By carefully selecting the thickness to accommodate the carrier cycloid paths, the device maintains effective ExB drift while minimizing the volume of the semiconductor layer and overall device complexity
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 enhances ExB power output by selectively capturing the overriding carrier current, allowing for efficient energy conversion with potential Carnot efficiency, eliminating the need for a heat sink and enabling operation over a wide range of temperatures.
Implementation Method 1
The ExB drift is a well-known, but counterintuitive phenomenon: in the presence of a magnetic field and an electric field perpendicular to each other, electrical carriers move along cycloid paths in the same average direction independently of their charge
Implementation Method 2
in the presence of a magnetic field and an electric field perpendicular to each other, electrical carriers move along cycloid paths
Data Source
AI summary
This invention describes a thermoelectric energy generation device based on the ExB drift in a semiconductor. The material is in depletion mode to avoid cancellation of the electric field by space charges. Under ideal, infinite mobility, zero-collision conditions, electrons and holes drift in the same direction, perpendicularly to the electric and magnetic fields, resulting in a zero-output current. However, when mobility is finite, their differing properties such as mobility, effective mass, and charge, manifest themselves as different drift velocity and drift direction resulting in a net output current and power. This invention leverages carriers' properties to accentuate these differences and maximize the output power. Quantities being optimized include, mobility, the product of mobility and the magnetic field, positioning electrodes along the drift axis of the overriding carriers, and adjusting the thickness of the semiconductor layer to accommodate the cycloid motion of one type of carrier but not the other.