AlInGaN Stress Control Layer for Nitride Semiconductor Efficiency
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Solution Overview
Problem
The lattice mismatch between p-type carrier blocking layers and light emitting layers in nitride semiconductor structures leads to crystal quality degradation and compressive stress, reducing internal quantum efficiency and light emitting efficiency in semiconductor light emitting devices.
Innovation Solution
Incorporating an AlxInyGa1-x-yN stress control layer between the light emitting layer and the p-type carrier blocking layer to mitigate lattice mismatch and compressive stress, thereby improving crystal quality and confining electrons and holes effectively within quantum well layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a p-type carrier blocking layer is disposed directly on the light emitting layer to confine carriers and improve light emitting efficiency, then carrier confinement is enhanced, but lattice mismatch causes crystal quality degradation and compressive stress
Solution Approach 1:
An AlInGaN stress control layer is introduced as an intermediary between the InGaN light emitting layer and the AlGaN carrier blocking layer. This intermediate layer has a band gap larger than the well layer and serves as a buffer to reduce lattice mismatch, thereby preventing crystal quality degradation while maintaining effective carrier confinement in the quantum well layers
Solution Approach 2:
The patent uses a composite structure combining AlInGaN stress control layer and AlGaN carrier blocking layer. The AlInGaN layer with specific composition (AlxInyGa1-x-yN where x+y<1) creates a graded transition that reduces sudden lattice mismatch, while the AlGaN layer provides high band gap for carrier blocking, together forming a composite solution that addresses both crystal quality and carrier confinement requirements
2Reliability
If a p-type carrier blocking layer with high band gap is used to increase electron-hole recombination rate, then internal quantum efficiency is improved, but compressive stress from lattice mismatch reduces light emitting efficiency
Solution Approach 1:
The AlInGaN stress control layer acts as a mediator that reduces compressive stress transmitted from the AlGaN carrier blocking layer to the InGaN quantum well layers. By having a band gap larger than the well layer and appropriate lattice constant, it buffers the stress while allowing the AlGaN layer to maintain its carrier blocking function for high internal quantum efficiency
Solution Approach 2:
The patent changes the material composition parameters by using AlxInyGa1-x-yN with specific x and y values where x+y<1. This parameter adjustment optimizes the lattice constant and band gap of the stress control layer to match intermediate values between InGaN and AlGaN, thereby reducing compressive stress while maintaining effective carrier confinement
Data Source
AI summary
A nitride semiconductor structure and a semiconductor light emitting device including the same are revealed. The nitride semiconductor structure mainly includes a stress control layer disposed between a light emitting layer and a p-type carrier blocking layer. The p-type carrier blocking layer is made from AlxGa1-xN (0<x<1) while the stress control layer is made from AlxInyGa1-x-yN (0<x<1, 0<y<1, 0<x+y<1). The light emitting layer has a multiple quantum well structure formed by a plurality of well layers and barrier layers stacked alternately. There is one well layer disposed between the two barrier layers. Thereby the stress control layer not only improves crystal quality degradation caused by lattice mismatch between the p-type carrier blocking layer and the light emitting layer but also reduces effects of compressive stress on the well layer caused by material differences.