Group III Nitride Semiconductor Defect Reduction via Intermittent Gas Etching
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Solution Overview
Problem
Group III nitride semiconductor light-emitting devices face an increase in polarity inversion defect density during epitaxial growth, leading to reduced crystallinity and potential damage from hydrogen gas in the growth atmosphere.
Innovation Solution
A method involving the selective use of nitrogen and hydrogen gas mixtures during specific phases of semiconductor layer growth, where hydrogen gas is supplied during intermission phases to etch polarity inversion defects and then paused during the growth of the p-type InGaN layer to prevent damage, with the ratio of hydrogen to nitrogen gas adjusted to 20-100% for optimal results.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mixture of nitrogen gas and hydrogen gas is supplied during the growth phase, then polarity inversion defects can be etched, but the crystallinity of the semiconductor layer deteriorates
Solution Approach 1:
The patent applies preliminary action by supplying hydrogen gas during the intermission phase before the growth phase to etch polarity inversion defects from the surface of the previously formed semiconductor layer. This preliminary defect removal prepares a cleaner surface for subsequent growth, allowing the next layer to be formed with lower initial defect density without exposing the growing layer to hydrogen damage
Solution Approach 2:
The patent implements periodic action by alternating between growth phases (supplying nitrogen gas) and intermission phases (supplying hydrogen gas mixture). During intermission phases, hydrogen gas etches defects from the surface, while during growth phases, nitrogen gas enables proper layer formation. This periodic switching allows defect removal without continuous exposure that would damage crystallinity
Solution Approach 3:
The patent converts the harmful effect of hydrogen gas (which can damage semiconductor layers during growth) into a beneficial effect by timing its supply during intermission phases when no growth occurs. The hydrogen gas selectively etches polarity inversion defects from the surface without incorporating into the crystal structure, transforming a potentially harmful substance into a useful defect-removal tool
2Volume of moving object
If epitaxial growth progresses, then semiconductor layer thickness increases, but polarity inversion defect density increases
Solution Approach 1:
The patent applies preliminary action by performing defect etching during intermission phases before each growth phase. This resets the surface defect density before new material is deposited, preventing the cumulative buildup of polarity inversion defects that normally occurs with progressive growth
Solution Approach 2:
The patent implements periodic action by interrupting growth at regular intervals (intermission phases) to perform defect removal. This periodic reset mechanism prevents the monotonic increase in defect density, allowing thick layers to be grown while maintaining consistently low defect densities throughout the structure
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 polarity inversion defect density in the p-type semiconductor layer, enhancing crystallinity and preventing damage, resulting in a semiconductor light-emitting device with improved performance and lower drive voltage.
Implementation Method 1
The semiconductor layer can be etched by hydrogen gas. Since bonding strength between atoms is weak in polarity inversion defects, a semiconductor layer having such defects is readily etched.
Data Source
AI summary
The present techniques provide a method for producing a Group III nitride semiconductor light-emitting device, with suppression of an increase in polarity inversion defect density. The production method includes an n-type semiconductor layer formation step, a light-emitting layer formation step, and a p-type semiconductor layer formation step. The p-type semiconductor layer formation step includes a p-type cladding layer formation step. The p-type cladding layer formation step includes a first p-type semiconductor layer formation step for forming a p-type AlGaN layer, a first semiconductor layer growth intermission step after the first p-type semiconductor layer formation step, and a p-type InGaN layer formation step after the first semiconductor layer growth intermission step. In the first semiconductor layer growth intermission step, a mixture of nitrogen gas and hydrogen gas is supplied to the substrate.