Nitride Semiconductor Light Emitting Device Superlattice Layer Doping
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Solution Overview
Problem
Current semiconductor light emitting devices, particularly those using group III nitride semiconductors, face challenges in achieving high light emission efficiency due to limitations in the recombination of electrons and holes in the active layer, which affects internal quantum efficiency.
Innovation Solution
The method involves forming a superlattice layer by alternately stacking nitride layers with different energy bandgaps, doped with a p-type dopant like magnesium, and adjusting the flow rate of the p-type dopant source gas to maintain a controlled doping concentration, thereby enhancing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a superlattice layer is formed by alternately stacking nitride layers with different energy bandgaps and doping them with p-type dopant, then light emission efficiency is improved, but device complexity increases
Solution Approach 1:
The superlattice layer is divided into multiple alternating nitride layers with different energy bandgaps (e.g., AlGaN and GaN layers), each contributing differently to carrier confinement and light emission. This segmentation allows optimization of light emission efficiency through controlled electron-hole recombination in each layer while maintaining a manageable repeating structure pattern.
Solution Approach 2:
Different regions of the superlattice layer are doped with p-type dopant at varying concentrations to create localized zones with different electrical properties. This local quality variation enables precise control over carrier distribution and recombination efficiency in specific layers, improving overall light emission while allowing the rest of the device to maintain simpler structures.
2Productivity
If the flow rate of p-type dopant source gas is adjusted to control doping concentration in the superlattice layer, then light emission efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The flow rate of p-type dopant source gas is dynamically adjusted during the growth process rather than maintained at a constant rate. The flow rate is reduced in the growth termination period (by no greater than about half) compared to the growth initiation period, allowing precise control over the doping concentration profile in the superlattice layer to optimize light emission efficiency while managing manufacturing complexity.
Solution Approach 2:
The doping process is applied periodically with varying intensities corresponding to different growth stages. By implementing periodic adjustments to the dopant flow rate (higher at initiation, reduced at termination), the method achieves controlled doping concentration that enhances light emission efficiency without requiring continuously high-precision control throughout the entire growth process.
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 increases light emission efficiency by optimizing the superlattice layer structure, reducing operational voltage, and maintaining or increasing the amount of emitted light, resulting in a nitride semiconductor light emitting device with improved performance.
Implementation Method 1
the recombination of electrons and holes in the active layer leads to the emission of light
Implementation Method 2
The forming of the superlattice layer is performed by adjusting a flow rate of a p-type dopant source gas
Data Source
AI summary
A method of manufacturing a nitride semiconductor light emitting device which includes forming an n-type semiconductor layer, forming an active layer on the n-type semiconductor layer, forming a superlattice layer by alternately stacking at least two nitride layers made of InxAlyGa(1-x-y)N (0≦x≦1, 0≦y≦1, and 0≦x+y≦1) having different energy bandgaps from each other and doped with a p-type dopant, and forming a p-type semiconductor layer on the superlattice layer. The forming of the superlattice layer is performed by adjusting a flow rate of a p-type dopant source gas to reduce the flow rate in a growth termination period of the superlattice layer by no greater than about half of the flow rate in a growth initiation period of the superlattice layer while being doped with the p-type dopant.