GaN-on-Si Nitride Structure With Iron Doping for Low Insertion Loss
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Solution Overview
Problem
The high resistivity of silicon substrates used in GaN on Si leads to insertion loss due to parasitic channels, and the use of silicon nitride layers or deep-level dopants results in poor epitaxial quality and rough GaN surfaces.
Innovation Solution
A semiconductor structure incorporating a substrate with a specific iron element distribution, including a first nitride layer, a polarity inversion layer, and a second nitride layer, which convert non-metallic to metallic polarity surfaces, suppressing parasitic channel generation through deep-level dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon nitride layer is used to suppress parasitic channel, then insertion loss is reduced, but the GaN epitaxial layer cannot be flatly grown
Solution Approach 1:
The patent removes the silicon nitride layer from the structure and replaces it with an iron-doped aluminum nitride layer. This extraction of the problematic silicon nitride layer eliminates the flatness issue while maintaining the parasitic channel suppression function through the iron deep-level dopant mechanism.
Solution Approach 2:
The patent changes the material composition by introducing iron as a deep-level dopant in the aluminum nitride layer. This parameter change (adding iron doping) provides an alternative mechanism for suppressing parasitic channels without requiring a silicon nitride layer, thereby resolving the flatness problem while maintaining electrical performance.
2Reliability
If excessive deep-level dopants are used to suppress parasitic channel, then insertion loss is reduced, but the GaN epitaxial surface becomes rough
Solution Approach 1:
The patent applies local quality by concentrating the iron doping specifically in the aluminum nitride layer adjacent to the silicon substrate, rather than using excessive dopants throughout the entire GaN structure. This localized approach suppresses parasitic channels at the critical interface while maintaining good epitaxial surface quality in the GaN layer.
Solution Approach 2:
The patent creates a composite structure by combining aluminum nitride with iron doping to form an iron-doped aluminum nitride layer. This composite material provides both the structural support of aluminum nitride and the parasitic channel suppression of iron deep-level dopants, achieving a balance between electrical performance and surface quality.
3Reliability
If iron element is introduced to suppress parasitic channel, then carrier concentration is reduced, but the complexity of element distribution control increases
Solution Approach 1:
The patent segments the iron element distribution into distinct regions: high iron concentration in the aluminum nitride layer for parasitic channel suppression, and low iron concentration in the GaN layers for maintaining epitaxial quality. This segmented approach provides controlled parasitic channel suppression without excessive complexity in element distribution management.
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 structure effectively reduces parasitic channel formation, enhancing epitaxial quality and reducing carrier concentration, thereby improving high-frequency performance.
Implementation Method 1
The polarity inversion layer is located on a surface of the first nitride layer to convert a non-metallic polarity surface of the first nitride layer into a metallic polarity surface
Implementation Method 2
The substrate, the first nitride layer, the polarity inversion layer, and the second nitride layer include iron element... iron element can generate a deep-level dopant in the above structure to suppress the generation of a parasitic channel
Data Source
AI summary
A semiconductor structure, including a substrate, a first nitride layer, a polarity inversion layer, a second nitride layer, and a third nitride layer, is provided. The first nitride layer is located on the substrate. The polarity inversion layer is located on a surface of the first nitride layer to convert a non-metallic polarity surface of the first nitride layer into a metallic polarity surface. The second nitride layer is located on the polarity inversion layer. The third nitride layer is located on the second nitride layer. The substrate, the first nitride layer, the polarity inversion layer, and the second nitride layer include iron element.