Nitride Light Emitting Structure with P-Layer Regrowth Isolation
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Solution Overview
Problem
In micro LED displays, the contamination of wafers during the crystal growth and regrowth process leads to the formation of unintended n layers, reducing light emission efficiency, especially when the regrowth interface is near the active layers.
Innovation Solution
A light emitting element with a group III nitride semiconductor structure that includes a substrate, n layer, active layers, electron blocking layers, and p layers, where the regrowth interface is kept away from the second active layer and sandwiched between p-type layers to prevent non-light-emitting recombination, and the use of Mg-doped non-n layers to neutralize unintended n-type impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the wafer is taken out of the growth furnace and charged back in to regrow the semiconductor layer, then the groove formation step can be completed, but the wafer becomes contaminated with impurities that form unintended n layers at the regrowth interface, reducing light emission efficiency
Solution Approach 1:
A protective film is formed on the groove bottom surface before regrowth to prevent impurity contamination. This preliminary protective action ensures that when the wafer is removed and reinserted for regrowth, the interface remains clean and free from unintended n-layer formation, thus maintaining light emission efficiency while still allowing groove formation to proceed
Solution Approach 2:
The protective film acts as an intermediary layer between the groove structure and the regrown semiconductor layer. This intermediate protective layer prevents direct contact between impurities and the regrowth interface, eliminating the harmful effect of impurity contamination while allowing the regrowth process to complete successfully
2Device complexity
If the regrowth interface is positioned close to the active layer to reduce device complexity, then fewer layers are needed, but light emission efficiency deteriorates fatally due to impurity contamination at the interface
Solution Approach 1:
The protective film serves as a mediator between the groove structure and the active layer region. Even when the regrowth interface is positioned close to the active layer, the protective film prevents impurity contamination, allowing the interface to be near the active layer without sacrificing light emission efficiency
3Reliability
If Mg-doped non-n layers are added to neutralize unintended n-type impurities, then light emission efficiency is maintained, but the device structure becomes more complex
Solution Approach 1:
Mg-doped non-n layers are introduced to convert the harmful effect of unintended n-type impurities into a beneficial neutralization effect. The Mg doping provides positive charge compensation that neutralizes the unintended n-type carriers, turning the harmful impurity contamination into a controlled and compensated condition that maintains light emission efficiency
Data Source
AI summary
A light emitting element includes: a substrate; an n layer over the substrate as defined herein; a first active layer over the n layer as defined herein; a middle layer over the first active layer as defined herein; a second active layer over the middle layer as defined herein; a first electron blocking layer over the second active layer as defined herein; a groove having a depth reaching the middle layer from a side of the first electron blocking layer; a first p layer over the first electron blocking layer as defined herein; and a second p layer over the middle layer exposed on a bottom surface of the groove as defined herein, and each of the first p layer and the second p layer includes a second electron blocking layer and a first contact layer provided over the second electron blocking layer.