Semiconductor Light Emitting Device With Graded P-Type Layer
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Solution Overview
Problem
Current semiconductor light emitting devices face challenges in enhancing luminous efficiency and quantum efficiency due to limitations in hole injection efficiency and thin film crystallinity when increasing p-type impurity concentration.
Innovation Solution
The semiconductor light emitting device incorporates a p-type semiconductor layer with alternately stacked first and second layers, where the impurity concentration of the first layers increases away from the active layer, and the second layers have lower impurity concentrations, while their thicknesses are gradually increased, to improve hole injection efficiency without degrading crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the p-type impurity concentration is increased to improve hole injection efficiency, then the luminous efficiency and quantum efficiency are improved, but the thin film crystallinity is degraded
Solution Approach 1:
The p-type semiconductor layer is divided into multiple sub-layers with different impurity concentrations. The first sub-layer has a first p-type impurity concentration, while the second sub-layer has a second p-type impurity concentration higher than the first. This segmentation allows the device to benefit from high impurity concentration (improved hole injection) in the second sub-layer while the first sub-layer maintains better crystallinity, thus resolving the contradiction between luminous efficiency and thin film crystallinity.
Solution Approach 2:
Different regions of the p-type semiconductor layer are assigned different impurity concentrations according to their specific functional requirements. The first sub-layer closer to the active layer uses a lower impurity concentration to maintain crystallinity and reduce defect formation, while the second sub-layer uses a higher impurity concentration to enhance hole injection efficiency. This local optimization resolves the contradiction by applying the appropriate impurity concentration in the appropriate location.
2Productivity
If the p-type impurity concentration is increased to enhance hole injection, then the electron-hole combination efficiency is improved, but the device complexity increases
Solution Approach 1:
The p-type semiconductor layer is segmented into two sub-layers with different impurity concentrations to improve electron-hole combination efficiency. The first sub-layer with lower impurity concentration and the second sub-layer with higher impurity concentration work together to enhance hole injection while maintaining manageable structural complexity through a clear two-layer configuration.
Solution Approach 2:
The impurity concentration parameter is changed across different sub-layers of the p-type semiconductor layer. By varying the p-type impurity concentration from the first sub-layer to the second sub-layer, the device achieves improved electron-hole combination efficiency without requiring overly complex structural modifications, thus resolving the contradiction between performance improvement and 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 enhances electron-hole combination efficiency and increases active layer luminance by effectively distributing holes and maintaining thin film quality, leading to improved light output.
Implementation Method 1
Impurity concentrations of the plurality of first layers increase in a direction away from the n-type semiconductor layer. Each of the plurality of second layers may have an impurity concentration lower than that of the first layers immediately adjacent thereto.
Implementation Method 2
Nitride semiconductor light emitting devices may be provided as light emitting devices having an active layer emitting light of various colors, including blue and green, through the recombination of electrons and holes.
Data Source
AI summary
There is provided a semiconductor light emitting device. The device includes an n-type semiconductor layer, and a p-type semiconductor layer. The p-type semiconductor layer includes a plurality of first layers and second layers, each containing a p-type impurity and are alternately stacked. The impurity concentrations of the plurality of first layers increase in a direction away from the n-type semiconductor layer. An active layer is disposed between the n-type semiconductor layer and the p-type semiconductor layer.