GaN Hetero-junction Drift Region Charge Distribution for Breakdown Voltage
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Solution Overview
Problem
Semiconductor devices with a hetero-junction structure on conductive substrates face a trade-off between breakdown voltage and on-resistance, where improving one typically compromises the other, and existing solutions do not effectively enhance breakdown voltage in GaN devices on conductive substrates.
Innovation Solution
A semiconductor device with a hetero-junction structure comprising a first GaN-type semiconductor layer and a second GaN-type semiconductor layer, where the second layer has a greater bandgap energy, and electrodes are positioned to generate a 2-dimensional electron gas (2DEG) channel with a total fixed charge quantity between 0.5×10^13 to 1.5×10^13 cm^-2, optimizing the electrical field distribution to enhance breakdown voltage and reduce on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hetero-junction structure with equal 2DEG and 2DHG quantities is used, then breakdown voltage is improved, but this solution is limited to insulating substrates and does not improve breakdown voltage in GaN devices on conductive substrates
Solution Approach 1:
The patent applies local quality by creating different regions with distinct charge densities within the drift region. Specifically, a first region with higher charge density (0.5×10^13 to 5×10^13 cm^-2) and a second region with lower charge density (0.5×10^13 to 2×10^13 cm^-2) are formed adjacent to the hetero-junction. This spatial differentiation of charge density allows the device to achieve high breakdown voltage on conductive substrates by optimizing the electrical field distribution locally rather than uniformly across the entire structure.
Solution Approach 2:
The patent changes the charge density parameter from the conventional equal distribution to a graded distribution with two distinct regions. By controlling the total fixed charge quantity in the range of 0.5×10^13 to 7×10^13 cm^-2 and creating a non-uniform spatial distribution, the device achieves improved breakdown voltage characteristics specifically adapted for conductive substrates, representing a parameter change from uniform to non-uniform charge distribution.
2Reliability
If breakdown voltage is improved through hetero-junction structure, then voltage resistance increases, but on-resistance increases as well due to the trade-off relationship
Solution Approach 1:
The patent resolves the trade-off between breakdown voltage and on-resistance by applying local quality through spatially differentiated charge density regions. The first region with higher charge density (0.5×10^13 to 5×10^13 cm^-2) located adjacent to the hetero-junction provides strong field termination for high breakdown voltage, while the second region with lower charge density (0.5×10^13 to 2×10^13 cm^-2) maintains low scattering and high carrier mobility for low on-resistance. This local optimization allows simultaneous improvement of both parameters.
Solution Approach 2:
The patent moves from a conventional uniform charge distribution (one-dimensional approach) to a two-dimensional charge density gradient structure. By introducing a spatial dimension of charge density variation with distinct regions at different positions adjacent to the hetero-junction, the device achieves independent optimization of breakdown voltage (controlled by the higher charge density region) and on-resistance (controlled by the lower charge density region), effectively breaking the traditional trade-off relationship.
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 solution effectively improves breakdown voltage while maintaining low on-resistance in GaN devices on conductive substrates by balancing the electrical field distribution, achieving a semiconductor device with enhanced voltage resistance and reduced on-resistance.
Implementation Method 1
The 2-dimensional electron gas is generated by a polarization in the first GaN-type semiconductor layer adjacent to an interface between the first GaN-type semiconductor layer and the second GaN-type semiconductor layer
Data Source
AI summary
A semiconductor device includes a conductive substrate, a channel forming layer, a first electrode, and a second electrode. The channel forming layer is located above the conductive substrate and includes at least one hetero-junction structure. The hetero-junction structure includes a first GaN-type semiconductor layer providing a drift region and a second GaN-type semiconductor layer having a bandgap energy greater than the first GaN-type semiconductor layer. A total fixed charge quantity of charges in the first GaN-type layer and the second GaN-type layer is from 0.5×1013 to 1.5×1013 cm−2. The charges in the first GaN-type layer and the second GaN-type layer include charges generated by the polarization in the first GaN-type layer. Accordingly, the semiconductor device capable of improving a break-down voltage and decreasing an on-resistance is obtained.