Nitride Semiconductor FET Carbon Concentration Gradient
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Solution Overview
Problem
Existing nitride semiconductor field effect transistors lack sufficient reliability and lifetime improvement, particularly in high-voltage off-states, as discussed in related-art transistors.
Innovation Solution
A field effect transistor structure comprising a substrate, buffer layer, high resistance layer, channel layer, and nitride semiconductor barrier layer with specific carbon concentration ranges in each layer to enhance reliability, where the carbon concentration in the buffer layer is between 0.8×10^19/cm^3 and 1.0×10^21/cm^3, in the high resistance layer between 3.7×10^18/cm^3 and 1.0×10^21/cm^3, and in the channel layer between 1.4×10^19/cm^3 and 1.0×10^21/cm^3, with the carbon concentration in the high resistance layer gradually increasing towards the channel layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon concentration is controlled in the buffer layer and high resistance layer, then reliability and lifetime are improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling carbon concentration within specific ranges (0.8×10^19 to 1.0×10^21/cm³ in buffer layer, 3.7×10^18 to 1.0×10^21/cm³ in high resistance layer) to resolve the contradiction between improving reliability and maintaining manufacturing feasibility. This quantitative parameter control enables both enhanced transistor lifetime and practical manufacturability.
Solution Approach 2:
The patent implements local quality by creating spatial variation in carbon concentration across different layers and regions. The buffer layer and high resistance layer have distinct carbon concentration ranges, and the high resistance layer exhibits a gradient profile, optimizing local electrical properties to achieve overall device reliability without uniform complexity throughout the structure.
2Object-generated harmful factors
If carbon concentration in high resistance layer increases towards channel layer, then leak current is suppressed, but manufacturing complexity increases
Solution Approach 1:
The patent uses parameter changes by establishing a carbon concentration gradient in the high resistance layer that increases from 3.7×10^18 to 1.0×10^21/cm³ towards the channel layer interface. This controlled parameter variation suppresses leak current through the harmful factor mechanism while maintaining a manufacturable gradient profile rather than requiring complex multi-layer structures.
Solution Approach 2:
The patent converts the potential harm of complex carbon concentration profiling into a benefit by deliberately designing the gradient to suppress leak current. The increasing carbon concentration towards the channel layer creates a potential barrier that blocks harmful leak current, transforming what could be a manufacturing complexity issue into a functional advantage.
Data Source
AI summary
In a field effect transistor, a carbon concentration in a buffer layer at the side closer to a high resistance layer is not less than 0.8×1019/cm3 and not more than 1.0×1021/cm3, a carbon concentration in the high resistance layer at the side closer to the buffer layer is not less than 3.7×1018/cm3 and not more than 1.0×1021/cm3, and a carbon concentration in the high resistance layer at the side closer to the channel layer is not less than 1.4×1019/cm3 and not more than 1.0×1021/cm3.