Semiconductor Light Emitting Element with Ring Portions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor light emitting elements with nitride-based semiconductor layers grown on mismatched substrates, such as sapphire, suffer from crystal defects (threading dislocations) that reduce luminous efficiency, especially under high current or temperature conditions, as carriers can still access these defects despite initial pit formation to prevent recombination.
Innovation Solution
A semiconductor light emitting element design featuring pyramidal pits with inclined side surfaces and a multi-quantum well structure, where the active layer is grown on the pit's inclined surface at a slower rate, and ring portions with a smaller band gap are formed around the threading dislocations to further prevent carrier access, maintaining high efficiency even under high current or temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyramidal pits are formed to surround threading dislocations, then carrier access to dislocations is reduced, but luminous efficiency still deteriorates under high current or temperature conditions
Solution Approach 1:
The patent applies local quality by creating ring portions with different band gap energies at specific locations within the active layer. The ring portions surrounding threading dislocations have a smaller band gap than the central portion, creating localized energy level differences that prevent carrier access to dislocation sites while maintaining efficient recombination in the central region. This spatial variation in band gap structure addresses the contradiction by locally modifying carrier behavior without compromising overall luminous efficiency.
Solution Approach 2:
The patent utilizes parameter changes by varying the band gap energy parameter across different regions of the active layer. By creating a band gap energy gradient where the ring portions have smaller band gaps and the central portion has larger band gaps, the invention changes the energy parameters to control carrier distribution. This parameter variation prevents carriers from reaching threading dislocations through the ring portions while maintaining high efficiency in the central emission region, even under high current and temperature conditions.
2Manufacturing precision
If the active layer is grown on inclined pit surfaces at slower rates, then pit formation is improved, but additional structure complexity is introduced
Solution Approach 1:
The patent applies segmentation by dividing the active layer into distinct functional regions: central portions for light emission and surrounding ring portions for carrier blocking. This segmentation is achieved through the multi-quantum well structure where different quantum well regions serve different purposes. The slower growth rate on inclined surfaces naturally creates this segmented structure, with the ring portions forming around the pits and the central portions forming over the pit openings,从而实现功能分区 without requiring additional complex processing steps.
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
The design effectively reduces carrier access to threading dislocations, maintaining high light emission efficiency and preventing luminous efficiency deterioration even when driven by large currents or operated at high temperatures.
Implementation Method 1
An active layer is deposited by epitaxy on the structured surface. The structured surface is produced in the epitaxy installation and the active layer follows the structuring of the structured surface at least in some regions in a conformal manner or at least in some sections essentially in a conformal manner.
Implementation Method 2
pyramidal pits with inclined side surfaces and a multi-quantum well structure, where the active layer is grown on the pit's inclined surface at a slower rate, and ring portions with a smaller band gap are formed around the threading dislocations to further prevent carrier access
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A semiconductor light emitting element includes: a pit formation layer (13) formed on the first semiconductor layer and having a pyramidal pit (PT); and an active layer (14) formed on the pit formation (13) layer and having a flat portion (FW(1)-FW(n)) and an embedded portion (IW(1)-IW(n)) which is formed so as to embed the pit. The active layer has a multi-quantum well structure having at least one well layer (W(1)-(n)) and one barrier layer (B(1)-B((n)) laminated alternately in which each well layer and each barrier layer lie one upon another. The flat portion has a flat well portion corresponding to the well layer. The embedded portion has an embedded well portion corresponding to the well layer. The embedded well portion has a ring portion (RW(1)-RW(n)) which is formed in an interface with the flat well portion so as to surround the threading dislocation. The ring portion has a band gap smaller than that of the flat well portion.