Nitride Light-Emitting Layer Structure for Low-Loss UV Emission
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Solution Overview
Problem
Increasing the Al composition ratio in nitride semiconductor layers to reduce optical absorption leads to stress, cracks, defects, and increased electrical resistance in nitride semiconductor laser elements due to lattice mismatch and decreased impurity concentration as acceptors or donors.
Innovation Solution
A nitride semiconductor light-emitting element with specific layer configurations, including N-type and P-type cladding layers, optical guide layers, and interlayers with controlled band gap energies and impurity concentrations to reduce optical loss while maintaining low Al composition ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the Al composition ratio of semiconductor layers is increased to reduce optical absorption, then optical loss decreases, but stress and lattice mismatch increase causing breaks and cracks
Solution Approach 1:
The patent applies local quality by assigning different Al composition ratios to different layers: the optical guide layer uses a lower Al composition ratio (3-10%) to maintain structural integrity, while the cladding layers use higher Al composition ratios (10-20%) to provide optical confinement. This spatial differentiation allows each layer to have properties optimized for its specific function without compromising overall device reliability.
Solution Approach 2:
The patent employs composite material structures by combining multiple AlGaN layers with different Al composition ratios and doping types (N-type and P-type). This creates a composite semiconductor structure where each layer contributes specific properties: lower Al-content layers provide mechanical stability while higher Al-content layers provide optical confinement, achieving both low optical loss and high structural reliability.
2Loss of energy
If the Al composition ratio of semiconductor layers is increased to reduce optical absorption, then optical loss decreases, but electrical resistance increases due to decreased impurity concentration
Solution Approach 1:
The patent applies local quality by implementing different doping strategies in different layers. The optical guide layer with lower Al composition ratio receives appropriate doping to achieve low electrical resistance, while cladding layers with higher Al composition ratios are optimized for optical confinement. This allows each layer to have its electrical and optical properties independently optimized.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying both the Al composition ratio and impurity concentration across different layers. By adjusting these parameters independently in each layer, the patent achieves optimal balance between optical loss reduction (requiring higher Al content) and electrical conductivity maintenance (requiring adequate impurity concentration).
Data Source
AI summary
A nitride semiconductor light-emitting element emits light and includes an N-type cladding layer, an N-side optical guide layer, an active layer, an electron blocking layer, a P-type interlayer, a P-side optical guide layer, and a P-type cladding layer. Average band gap energy of the electron blocking layer is higher than average band gap energy of the P-type cladding layer. Average band gap energy of the P-type interlayer is higher than average band gap energy of the P-side optical guide layer, and is smaller than the average band gap energy of the electron blocking layer. An average impurity concentration of the P-type interlayer is lower than an average impurity concentration of the electron blocking layer, and is higher than an average impurity concentration of the P-side optical guide layer. A peak wavelength of the light is less than 400 nm.