Normally-off 2DEG Channel via Impurity Doping
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Solution Overview
Problem
The complexity of manufacturing heterojunction field effect transistors (HFETs) with a 2-dimensional electron gas (2DEG) channel in a normally-off state is increased due to the need for etching and filling material layers or forming additional layers, which complicates the process.
Innovation Solution
A power electronic device is designed with a substrate and sequentially stacked lower and upper semiconductor layers, where the lattice constant difference under the gate is reduced by incorporating an impurity with a larger atomic number from the same group as the main component elements, allowing for a continuous and uniform upper semiconductor layer without the need for etching or additional layers, thereby achieving a normally-off state for the 2DEG channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If etching and filling material layers or forming additional layers is used to achieve normally-off state, then the 2DEG channel can be made normally-off, but the manufacturing process complexity increases
Solution Approach 1:
The patent changes the lattice constant parameter of the upper semiconductor layer by incorporating impurity elements (such as Al, In) to reduce the lattice constant difference between layers. This parameter change modifies the polarization field intensity, enabling the 2DEG channel to transition to a normally-off state without requiring etching or additional material layers, thus simplifying the manufacturing process while achieving the desired device state
Solution Approach 2:
The patent introduces impurity elements as intermediary substances within the upper semiconductor layer. These impurity elements act as mediators that adjust the lattice constant and polarization characteristics, enabling control over the 2DEG channel state without direct manipulation of the channel structure through etching or additional layers
2Ease of manufacture
If lattice constant difference is reduced by impurity incorporation, then manufacturing process is simplified, but device structure becomes more complex
Solution Approach 1:
The patent modifies the compositional parameters of the upper semiconductor layer by incorporating specific impurity elements with controlled concentrations. This changes the lattice constant and polarization properties, achieving the normally-off state through material composition adjustment rather than structural modification, thereby maintaining manufacturing simplicity while accounting for compositional 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 simplifies the manufacturing process of power electronic devices by eliminating the need for etching or forming additional layers, maintaining basic device characteristics while reducing the lattice constant difference and polarization field intensity, resulting in a normally-off 2DEG channel.
Implementation Method 1
A lattice constant difference between the lower and upper semiconductor layers under the gate is smaller than that in another region of the lower and upper semiconductor layers
Implementation Method 2
reducing the lattice constant difference and polarization field intensity
Data Source
AI summary
Power electronic devices including 2-dimensional electron gas (2DEG) channels and methods of manufacturing the same. A power electronic device includes lower and upper material layers for forming a 2DEG channel, and a gate contacting an upper surface of the upper material layer. A region below the gate of the 2DEG channel is an off region where the density of a 2DEG is reduced or zero. The entire upper material layer may be continuous and may have a uniform thickness. A region of the upper material layer under the gate contains an impurity for reducing or eliminating a lattice constant difference between the lower and upper material layers.