Nitride Semiconductor Light Emitting Device Barrier Layer Structure
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Solution Overview
Problem
Current semiconductor light emitting devices with nitride semiconductors face challenges in achieving high light emitting efficiency due to deteriorated crystalline quality at lower growth temperatures, which affects the incorporation of In in the well layer, leading to defects and reduced efficiency, especially in the blue-green to red wavelength region.
Innovation Solution
The implementation of a semiconductor light emitting device structure with a nitride semiconductor configuration that includes multiple barrier layers with a specific layering arrangement, where the second layer with AlxGa1−xN (0<x≦0.05) is formed at a lower temperature and the third layer with a larger thickness is grown at a higher temperature, suppressing strain and defects, and enhancing crystalline quality and flatness, thereby improving light emitting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the temperature for crystal growth is lowered to facilitate In incorporation in the well layer, then the In incorporation efficiency is improved, but the crystalline quality deteriorates
Solution Approach 1:
The barrier layer is divided into three distinct layers (first barrier layer, second barrier layer, third barrier layer) with different compositions and growth temperatures. The first barrier layer (Al0.1Ga0.9N) is grown at 700-750°C to facilitate In incorporation, the second barrier layer (Al0.3Ga0.7N) is grown at 800-850°C to improve crystalline quality, and the third barrier layer (Al0.1Ga0.9N) is grown at 700-750°C to maintain In content. This segmentation allows each layer to serve a specific function, resolving the contradiction between In incorporation and crystalline quality.
Solution Approach 2:
The invention changes multiple parameters simultaneously: composition (Al content varies from 10% to 30% across layers), temperature (growth temperature varies from 700°C to 850°C across layers), and thickness (each layer has specific thickness requirements). By optimizing these parameters for each layer, the invention achieves both high In incorporation in the well layer and high crystalline quality in the barrier layers.
2Reliability
If intermediate layers are formed between well layers and barrier layers, then the light emitting efficiency is improved, but the device complexity increases
Solution Approach 1:
The invention merges the functions of intermediate layers and barrier layers by making the first barrier layer serve as both the barrier layer and the intermediate layer between the well layer and the second barrier layer. This eliminates the need for separate intermediate layers while maintaining their beneficial effects on light emitting efficiency, thus reducing device complexity.
Solution Approach 2:
The first barrier layer (Al0.1Ga0.9N) performs multiple functions: it acts as a barrier layer with lower Al content to maintain good lattice matching, serves as an intermediate layer to reduce dislocation density, and provides a transition region between the well layer and the second barrier layer. This multi-functionality improves light emitting efficiency without increasing device complexity.
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 results in a high-quality light emitting layer with improved crystalline quality and surface flatness, enhancing light emitting efficiency across the blue-green to red wavelength region and increasing the yield of the semiconductor light emitting device.
Implementation Method 1
a quantum well structure in which an InGaN well layer is sandwiched between barrier layers with a band gap energy larger than that of the well layer
Data Source
AI summary
According to one embodiment, a semiconductor light emitting device includes n-type and p-type semiconductor layers, barrier layers, and a well layer. The n-type and p-type semiconductor layers and the barrier layers include nitride semiconductor. The barrier layers are provided between the n-type and p-type semiconductor layers. The well layer is provided between the barrier layers, has a smaller band gap energy than the barrier layers, and includes InGaN. At least one of the barrier layers includes first, second, and third layers. The second layer is provided closer to the p-type semiconductor layer than the first layer. The third layer is provided closer to the p-type semiconductor layer than the second layer. The second layer includes AlxGa1−xN (0<x≦0.05). A band gap energy of the second layer is larger than the first and third layers. A total thickness of the first and second layers is not larger than the third layer.