Charge-Balanced Schottky Barrier Diodes for High-Voltage GaN Rectifiers
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Solution Overview
Problem
High-voltage power rectifiers face challenges with slow switching speeds in bipolar silicon diodes and high manufacturing costs in unipolar silicon-carbide junction barrier Schottky diodes, while gallium-nitride diodes suffer from high peak electric fields limiting their reliable operation voltage.
Innovation Solution
A Schottky diode design featuring a semiconductor region with a two-dimensional carrier channel and a second conductivity type material that forms a depletion region under reverse bias, reducing peak electric fields and increasing breakdown voltage through a discontinuous second conductivity type material configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If gallium-nitride based diodes are used to operate at higher voltages, then voltage operating range is improved, but peak electric fields increase limiting reliable operation
Solution Approach 1:
The patent applies local quality by creating a depletion region with opposite polarity charge specifically at the high-field region near the Schottky contact. This localized charge compensation reduces peak electric fields only where they are most harmful, while maintaining the high voltage operating capability of the gallium-nitride material throughout the bulk device.
Solution Approach 2:
The patent introduces an intermediary mechanism - a depletion region formed by a material of second conductivity type - that mediates between the high voltage requirements and the peak electric field limitations. This depletion region acts as a buffer that redistributes and reduces peak fields while allowing the device to operate at higher voltages.
2Temperature
If bipolar silicon diodes are used for high voltage applications, then voltage handling capability is improved, but switching speeds decrease
Solution Approach 1:
The patent employs composite material structure by combining a semiconductor region with a material of second conductivity type to form a Schottky barrier diode. This composite structure integrates the high voltage handling capability of Schottky barriers with the fast switching characteristics of unipolar devices, achieving both objectives simultaneously.
3Speed
If unipolar silicon-carbide junction barrier Schottky diodes are used for high voltage operation, then switching speed is improved, but manufacturing costs increase
Solution Approach 1:
The patent applies parameter changes by adjusting the charge balance condition - specifically setting the net charge in the depletion region to be substantially equal to the net charge of the two-dimensional carrier channel. This parameter optimization enables high voltage operation with reduced peak fields using gallium-nitride material, which can be manufactured more cost-effectively than silicon-carbide while maintaining fast switching performance.
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 diode achieves higher breakdown voltage and reduced leakage current, enhancing reliability and switching speed, while maintaining a lower manufacturing cost compared to existing technologies.
Implementation Method 1
a second conductivity type material that forms a depletion region under reverse bias, reducing peak electric fields and increasing breakdown voltage
Implementation Method 2
an anode material in contact with at least a portion of the at least one two-dimensional channel and in contact with at least a portion of the material of the second conductivity type
Data Source
AI summary
A diode includes a semiconductor region having at least one two-dimensional carrier channel of a first conductivity type, the first conductivity type being one of a n-type and a p-type conductivity, the at least one two-dimensional channel having a net charge; a material of a second conductivity type, the second conductivity type being the other of the n-type and the p-type conductivity, disposed on the semiconductor region, the material of the second conductivity type having a net-charge in a depletion region that is substantially equal to the net-charge of the at least one two-dimensional channel in the semiconductor region when the diode is under reverse bias; an anode material in contact with at least a portion of the at least one two-dimensional channel and at least a portion of the material of the second conductivity type; and a cathode material in contact with the at least one two-dimensional carrier channel.