VCSEL Resonant Cavity on ELO Wing Regions for Crystal Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for fabricating Vertical Cavity Surface Emitting Lasers (VCSELs) face challenges in achieving good crystal quality, tolerating micron-level defects, and efficient mass production, particularly with III-nitride materials, due to issues with substrate thinning and crystal quality between the resonant cavity length, which affects device characteristics and yield.
Innovation Solution
A method involving epitaxial lateral overgrowth (ELO) and mechanical peeling to fabricate VCSELs with improved crystal quality, where the light emitting aperture is created on the wing region of an ELO III-nitride layer, allowing for controlled resonant cavity length and placement of DBR mirrors, independent of native substrate orientations, and enabling recycling of substrates for further device fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If substrate thinning is performed to achieve controlled resonant cavity length, then the cavity length precision is improved, but the crystal quality deteriorates due to increased dislocation density and stacking faults
Solution Approach 1:
The substrate processing is segmented into two distinct stages: first, VCSELs are fabricated on the substrate with standard thickness; second, the substrate is thinned and VCSELs are released only after fabrication is complete. This segmentation allows resonant cavity length to be controlled through epitaxial layer thickness rather than substrate thinning, preserving crystal quality while achieving precise cavity control.
Solution Approach 2:
The resonant cavity length is predetermined during the epitaxial growth stage by controlling the thickness of the active region and surrounding layers, rather than adjusting it later through substrate thinning. This preliminary action ensures both precise cavity length control and maintained crystal quality throughout subsequent processing.
2Ease of manufacture
If conventional fabrication methods are used on native substrates, then manufacturing simplicity is maintained, but device yield decreases due to micron-level defects and poor crystal quality
Solution Approach 1:
An epitaxial lateral overgrowth (ELO) layer is introduced as an intermediary between the native substrate and the VCSEL active region. This ELO layer acts as a defect-filtering mediator that blocks dislocations and stacking faults from propagating into the device region, thereby improving crystal quality and device yield while maintaining compatibility with conventional fabrication processes.
Solution Approach 2:
The fabrication approach changes the critical parameter for resonant cavity length from substrate thickness to epitaxial layer thickness. This parameter change enables precise cavity control through controlled epitaxial growth rather than mechanical substrate thinning, improving both crystal quality and device yield while maintaining manufacturing simplicity.
3Reliability
If III-nitride materials are used for VCSEL fabrication, then device characteristics are improved, but manufacturing challenges increase due to sensitivity to crystal quality and dislocation density
Solution Approach 1:
The ELO layer serves as a mediator that decouples the relationship between III-nitride material performance and substrate quality. By filtering defects at the ELO-substrate interface, the method enables high-performance III-nitride VCSELs to be fabricated on conventional substrates without requiring ultra-high crystal quality, thereby maintaining device characteristics while reducing manufacturing difficulty.
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 results in high-quality VCSELs with reduced dislocation density and stacking faults, improved thermal performance, and increased yield, facilitating mass production and integration of VCSELs in display applications with better communication capabilities.
Implementation Method 1
III-nitride-based semiconductor layers 105 are grown by ELO on the III-nitride substrate 101
Implementation Method 2
fabricating a resonant cavity and distributed bragg reflector mirrors for a vertical cavity surface emitting laser
Implementation Method 3
distributed bragg reflector mirrors
Data Source
AI summary
A method for fabricating a quality and manufacturable aperture for light emitting elements, such as vertical cavity surface emitting lasers (VCSELs), using epitaxial later overgrowth (ELO). A bar comprised of island-like III-nitride semiconductor layers is grown on a substrate using a growth restrict mask, and the island-like III-nitride semiconductor layers are fabricated into light-emitting resonating cavities across a smallest length of the bar. Apertures for the resonating cavities are also fabricated along the smallest length of the bar on wing regions of the epitaxial lateral overgrowth. Distributed Bragg reflectors (DBRs) are fabricated as mirrors for the resonant cavities on the bottom and top of the wing regions of the epitaxial lateral overgrowth.