Strained Semiconductor Junctions for UV LED Wavelength Tuning
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Solution Overview
Problem
Deep ultraviolet LEDs face limitations in efficiency due to internal polarization charges and lattice constant mismatch issues, leading to poor electrical-to-optical generation efficiency and high production costs.
Innovation Solution
A post-epitaxial semiconductor formation process is used to engineer a stressor region, altering the local band structure and optical properties to tune the emission wavelength and polarization of the LEDs, allowing for improved optical extraction efficiency and reduced internal strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional epitaxial semiconductor formation is used, then manufacturing process is simpler, but internal strain and polarization charges increase leading to poor electrical-to-optical generation efficiency
Solution Approach 1:
The patent applies preliminary action by introducing a stressor layer during the epitaxial growth process that pre-compensates for internal strain and polarization charges. This preliminary modification of the band structure during fabrication prevents energy losses during device operation, thereby improving electrical-to-optical generation efficiency before the device is put into service.
Solution Approach 2:
The patent changes physical parameters by modifying the band structure through controlled strain engineering. By adjusting the stressor layer's material composition and thickness, the patent alters the local band structure parameters (bandgap, effective mass) to optimize carrier recombination efficiency and reduce polarization-related energy losses.
2Loss of energy
If no stressor region is engineered, then manufacturing process is simpler and costs are lower, but optical extraction efficiency is poor due to internal strain
Solution Approach 1:
The patent changes the optical parameters of the semiconductor by introducing controlled strain through the stressor layer. This strain modification alters the refractive index and band structure, thereby improving optical extraction efficiency without requiring complex post-processing or expensive material substitutions.
Solution Approach 2:
The stressor layer acts as an intermediary element between the substrate and the active semiconductor layers. It mediates the strain distribution and polarization charge effects, providing a controlled interface that enhances optical extraction while maintaining manufacturing simplicity.
3Adaptability or versatility
If emission wavelength and polarization are not tuned, then device structure is simpler, but optical properties do not match application requirements
Solution Approach 1:
The patent enables tuning of emission wavelength and polarization by changing the strain parameters through the stressor layer. By adjusting the stressor's material composition, thickness, and positioning, the band structure can be modified to achieve desired optical properties without adding complex external tuning mechanisms.
Solution Approach 2:
The stressor layer serves multiple functions simultaneously: it controls strain distribution, tunes emission wavelength, adjusts polarization characteristics, and maintains structural integrity. This multi-functionality is achieved through a single integrated component rather than multiple separate tuning elements.
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 approach enhances the optical extraction efficiency and reduces production costs by minimizing internal strain and polarization-related issues, leading to more efficient deep ultraviolet light emission.
Implementation Method 1
engineer a stressor region, altering the local band structure and optical properties to tune the emission wavelength and polarization of the LEDs
Implementation Method 2
Semiconductor optoelectronic devices are efficient energy transformers which can convert electrical energy into optical energy
Data Source
AI summary
Light emitting semiconductor junctions are disclosed. An exemplary light emitting junction has a first electrical contact coupled to a first side of the junction. The exemplary junction also has a second electrical contact coupled to a second side of the junction. The exemplary junction also has a region of set straining material that exerts a strain on the junction and alters both: (i) an optical polarization, and (ii) an emission wavelength of the junction. The region of set straining material is not on a current path between said first electrical contact and said second electrical contact. The region of set straining material covers a third side and a fourth side of the light emitting junction along a cross section of the light emitting junction. The light emitting semiconductor junction device comprises a three-five alloy.