InAlN HEMT Intermediate Layer Blocks In Al Diffusion
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Solution Overview
Problem
InAlN-HEMTs face issues with high gate leakage current due to surface roughness and incorporation of In and Al into the GaN cap layer, which degrades electric characteristics and increases sheet resistance, while attempts to mitigate these with GaN layers or InAlGaN intermediate layers lead to compromised spontaneous polarization and increased sheet resistance.
Innovation Solution
A semiconductor device structure incorporating a GaN channel layer, an Inx1Aly1Ga1-x1-y1N barrier layer, an Inx2Aly2Ga1-x2-y2N intermediate layer with low In and Al composition, and a GaN cap layer, where the intermediate layer suppresses the incorporation of In and Al into the cap layer, thereby reducing sheet resistance and maintaining high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a GaN layer is formed on the InAlN layer to improve surface flatness, then gate leakage current is reduced, but In and Al are incorporated into the GaN layer causing electric characteristic degradation
Solution Approach 1:
An AlN intermediate layer is introduced between the InAlN barrier layer and the GaN cap layer. This intermediate layer acts as a mediator that prevents direct contact between In/Al atoms and the GaN layer, thereby blocking the incorporation of In and Al into the GaN cap layer while still allowing the GaN layer to smooth the surface and reduce gate leakage current.
2Reliability
If an InAlGaN intermediate layer with low Al and In composition is formed between InAlN layer and GaN layer to prevent In and Al incorporation, then electric characteristic is improved, but spontaneous polarization decreases and sheet resistance increases
Solution Approach 1:
The invention changes the compositional parameters of the intermediate layer by using pure AlN (100% Al composition) instead of InAlGaN with low Al and In composition. This parameter change allows the intermediate layer to effectively block In and Al incorporation into the GaN cap layer while maintaining high spontaneous polarization and low sheet resistance, as AlN has superior piezoelectric and polarization properties compared to InAlGaN.
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 structure effectively reduces gate leakage current, improves electric characteristics, and enhances the reliability of InAlN-HEMTs by minimizing the incorporation of In and Al into the cap layer, thus addressing the challenges of surface roughness and sheet resistance while maintaining high-frequency performance.
Implementation Method 1
an Inx2Aly2Ga1-x2-y2N (0.00≤x2≤0.04, 0.30≤y2≤0.60) intermediate layer... the intermediate layer suppresses the incorporation of In and Al into the cap layer
Data Source
AI summary
A semiconductor device includes a substrate, a channel layer containing GaN formed above the substrate, a barrier layer containing Inx1Aly1Ga1-x1-y1N (0.00≤x1≤0.20, 0.60≤y1≤1.00) formed above the channel layer, an intermediate layer containing Inx2Aly2Ga1-x2-y2N (0.00≤x2≤0.04, 0.30≤y2≤0.60) formed on the barrier layer, and a cap layer containing GaN formed on the intermediate layer.