Semi-Polar GaN Device Oxygen Reduction
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Solution Overview
Problem
Group III nitride semiconductor devices face challenges with high oxygen incorporation on nonpolar planes, leading to degraded electrical characteristics due to oxygen acting as a compensating impurity, especially in p-type nitride semiconductor layers.
Innovation Solution
The solution involves growing a Group III nitride semiconductor device with a p-type gallium nitride based semiconductor layer on a substrate with a primary surface inclined at an angle between 50 and 130 degrees from the c-axis, using a nitrogen atmosphere to reduce oxygen concentration and p-type dopant compensation, thereby improving electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If growth is performed on a nonpolar plane, then the crystal structure provides certain advantages, but oxygen is easily incorporated as impurity degrading electrical characteristics
Solution Approach 1:
The patent changes the substrate orientation parameter from conventional c-plane (0001) to semi-polar planes (10-10), (11-20), or (20-21) with specific inclination angles. This parameter change fundamentally alters the crystal surface properties, reducing oxygen incorporation while maintaining electrical characteristics. The specific angle ranges (50-90° or 90-130° from c-axis) are optimized to balance oxygen rejection with electrical performance.
Solution Approach 2:
The patent employs composite layer structures including GaN buffer layers, InGaN active layers, and AlGaN barrier layers grown on semi-polar substrates. This composite approach combines materials with different properties to achieve both low oxygen incorporation and good electrical characteristics that cannot be obtained with single-material systems.
2Reliability
If hydrogen atmosphere is used for growth, then reduction of other impurities is achieved, but oxygen from resident matter is desorbed and incorporated into the epitaxial film
Solution Approach 1:
The patent changes the atmospheric parameter from hydrogen to nitrogen during epitaxial growth. This parameter change prevents oxygen desorption from resident matter while still achieving impurity reduction, eliminating the harmful side effect of oxygen incorporation that occurs with hydrogen atmosphere growth.
3Reliability
If p-type dopant concentration is increased to compensate for oxygen, then electrical conductivity is maintained, but the ratio of oxygen to dopant concentration increases degrading device performance
Solution Approach 1:
The patent changes the substrate orientation parameter to semi-polar planes, which fundamentally reduces oxygen incorporation during growth. This parameter change allows achieving both low oxygen concentration and appropriate dopant concentration without the harmful high oxygen-to-dopant ratio that degrades device performance.
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 approach effectively reduces oxygen concentration and p-type dopant compensation in the semiconductor layer, enhancing the electrical performance of the device, particularly in light emitting devices with emission wavelengths between 440 and 600 nm.
Implementation Method 1
a first p-type gallium nitride based semiconductor layer and a second p-type gallium nitride based semiconductor layer in a nitrogen atmosphere
Data Source
AI summary
Provided is a Group III nitride semiconductor device, which comprises an electrically conductive substrate including a primary surface comprised of a first gallium nitride based semiconductor, and a Group III nitride semiconductor region including a first p-type gallium nitride based semiconductor layer and provided on the primary surface. The primary surface of the substrate is inclined at an angle in the range of not less than 50 degrees, and less than 130 degrees from a plane perpendicular to a reference axis extending along the c-axis of the first gallium nitride based semiconductor, an oxygen concentration Noxg of the first p-type gallium nitride based semiconductor layer is not more than 5×1017 cm−3, and a ratio (Noxg/Npd) of the oxygen concentration Noxg to a p-type dopant concentration Npd of the first p-type gallium nitride based semiconductor layer is not more than 1/10.