GaN Semiconductor Device Polarization Junction Voltage Resistance
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Solution Overview
Problem
AlGaN/GaN HFETs face challenges with current collapse due to high electric fields, which existing techniques like field plates and super junctions do not adequately address, especially at high voltages above 600 V, limiting energy efficiency and voltage resistance.
Innovation Solution
A semiconductor device utilizing a polarization junction with specific layer structures, including InzGa1-zN, AlxGa1-xN, and InyGa1-yN layers, optimized to reduce peak electric fields and enhance voltage resistance, allowing for the simultaneous formation of two-dimensional hole and electron gases to control current collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a field plate technique is used to control peak electric field, then voltage resistance is improved, but current collapse cannot be fully controlled at high voltages above 600 V
Solution Approach 1:
The device is divided into multiple functional regions: a first region with high Al composition (0.3-0.5) for voltage resistance, a second region with intermediate Al composition (0.15-0.3) for electric field distribution, and a third region with low Al composition (0.05-0.15) for low-resistance contact. This segmentation allows each region to optimize its function, resolving the contradiction between voltage resistance and current collapse control.
Solution Approach 2:
Different Al composition ratios are applied to different regions of the AlGaN layer to achieve local optimization. The first region has higher Al composition for withstanding high electric fields and providing voltage resistance, while the third region has lower Al composition for providing low-resistance electron supply, thus simultaneously achieving voltage resistance and current collapse control.
2Strength
If Al composition is increased to improve voltage resistance, then peak electric field is reduced, but electron supply capability deteriorates
Solution Approach 1:
The AlGaN layer is divided into regions with different Al compositions: the first region (x1=0.3-0.5) provides voltage resistance and electric field control, while the third region (x3=0.05-0.15) provides low-resistance electron supply. This local quality differentiation resolves the contradiction between voltage resistance and electron supply capability.
Solution Approach 2:
The AlGaN layer is segmented into multiple regions with gradient Al compositions, allowing each segment to fulfill its specific function: high-Al regions for voltage blocking and low-Al regions for electron supply, thus eliminating the trade-off between these opposing requirements.
3Object-affected harmful factors
If a dielectric film is used for passivation, then electron transfer is limited, but current collapse cannot be fully controlled
Solution Approach 1:
The AlGaN layer with intermediate Al composition (second region, x2=0.15-0.3) acts as an intermediary between the high-Al first region and the low-Al third region. This intermediate layer provides a transition zone that facilitates electron supply while maintaining electric field control, supplementing the dielectric film's passivation effect to achieve complete current collapse control.
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 proposed structure effectively reduces peak electric fields and current collapse, enabling high voltage resistance and low-loss operation in GaN-based semiconductor devices, particularly at high voltages, thereby improving energy efficiency and practical performance.
Implementation Method 1
makes use a two-dimensional electron gas (2DEG) generating at an AlGaN/GaN hetero-interface
Implementation Method 2
A semiconductor device utilizing a polarization junction with specific layer structures, including InzGa1-zN, AlxGa1-xN, and InyGa1-yN layers, optimized to reduce peak electric fields
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A low-loss GaN-based semiconductor device can be easily realized by making use of the polarization junction, fundamentally easing the peak electric field generating in a region of a conductive channel, and along with making high voltage resistance, and suppressing the generation of current collapse at the practical level. The semiconductor device has the InzGa1-zN layer 11 (where 0 ≤ z < 1), the AlxGa1-xN layer 12 (where 0 < x < 1), the InyGa1-yN layer 13 (where 0 ≤ y < 1) and the p-type InwGa1-wN layer 14 (where 0 ≤ w < 1) which are sequentially stacked on a base substrate of a C-plane sapphire substrate, etc. At a non-operating time, the two-dimensional hole gas 15 is formed in the InyGa1-yN layer 13 in the vicinity part of a hetero-interface between the AlxGa1-xN layer 12 and the InyGa1-yN layer 13, and the two-dimensional electron gas 16 is formed in the InzGa1-zN layer 16 in the vicinity part of a hetero-interface between the InzGa1-zN layer 11 and the AlxGa1-xN layer 12.