Nitride Semiconductor Laser Memory Effect Suppression
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Solution Overview
Problem
In nitride semiconductor surface emitting lasers, the memory effect caused by Mg doping leads to reduced light emission efficiency due to unintended Mg mixing into active layers, limiting the realization of a periodic gain structure where all intermediate layers need to be p-type for effective carrier injection.
Innovation Solution
The implementation of an Mg-doped layer and a nitride semiconductor layer containing In, arranged in order from the substrate, with the Mg-doped layer having a high doping concentration closer to the p-type spacer and a low concentration closer to the n-type spacer, and the nitride semiconductor layer with In inserted to suppress the memory effect, ensuring electrons are injected into all active layers while maintaining high purity and preventing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If an Mg-doped intermediate layer is used to enable carrier injection into all active layers, then the gain and output are improved, but the memory effect causes unintended Mg mixing into active layers reducing light emission efficiency
Solution Approach 1:
An undoped nitride semiconductor layer is introduced as an intermediary between the Mg-doped intermediate layer and the active layers. This intermediary layer acts as a barrier that prevents Mg diffusion into the active layers while still allowing carrier injection to proceed effectively, thus resolving the contradiction between achieving high laser output and maintaining layer purity
Solution Approach 2:
The intermediate layer structure is segmented into distinct functional zones: an Mg-doped region for carrier injection and an adjacent undoped nitride semiconductor region for preventing Mg diffusion. This segmentation allows each zone to perform its specific function without interfering with the other, enabling both high gain and high light emission efficiency
2Power
If all intermediate layers are made p-type to inject carriers into multiple active layers, then the gain structure is improved, but electron leakage between active layers occurs reducing efficiency
Solution Approach 1:
Different regions of the intermediate layer are assigned different doping characteristics: the region adjacent to the n-type spacer layer has higher Mg doping concentration to facilitate electron injection, while the region closer to the p-type spacer layer has lower doping concentration to reduce electron leakage. This local quality variation optimizes both carrier injection and energy efficiency
Solution Approach 2:
The Mg doping concentration is varied spatially within the intermediate layer, creating a gradient from high concentration near the n-type spacer to low concentration near the p-type spacer. This parameter change optimizes the balance between carrier injection efficiency and electron leakage prevention
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 configuration effectively suppresses the memory effect of Mg, ensuring high light emission efficiency and carrier injection into all active layers, thereby enhancing the gain and output of the nitride semiconductor surface emitting laser.
Implementation Method 1
an Mg-doped layer including at least Mg, and a nitride semiconductor layer including In, and the Mg-doped layer and the nitride semiconductor layer including In are provided in that order from a side of the substrate
Implementation Method 2
the nitride semiconductor layer with In inserted to suppress the memory effect, ensuring electrons are injected into all active layers while maintaining high purity and preventing light absorption
Implementation Method 3
ensuring electrons are injected into all active layers while maintaining high purity
Data Source
AI summary
A surface emitting laser in which a plurality of nitride semiconductor layers including a lower reflector, a plurality of active layers causing a gain by current injection, and an upper reflector are provided on a substrate, includes an n-type spacer layer formed between the lower reflector and an active layer closest to the lower reflector in the plurality of active layers, a p-type spacer layer formed between the upper reflector and an active layer closest to the upper reflector in the plurality of active layers, and an intermediate layer arranged between the plurality of active layers. The intermediate layer is configured from an Mg-doped layer including at least Mg, and a nitride semiconductor layer including In, and the Mg-doped layer and the nitride semiconductor layer including In are provided in that order from a side of the substrate.