VCSEL Reflective Structure for Current Confinement and Beam Control
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Solution Overview
Problem
Current semiconductor devices, particularly vertical cavity surface emitting lasers (VCSELs), face challenges in optimizing the design of reflective structures and current confinement layers to enhance light emission efficiency and reduce beam divergence.
Innovation Solution
The semiconductor device incorporates a cavity region with a specific reflective structure configuration, including a conductive area and insulating area in the second reflective structure, and a current confinement layer to manage current flow and radiation emission, with strategically placed openings in an insulating layer to minimize interference from the conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional VCSEL structure with mirror stacks and active region is used, then light can be emitted perpendicular to the active region, but beam divergence is high and light emission efficiency is not optimized
Solution Approach 1:
The VCSEL structure is segmented into multiple functional layers including separate reflective structures, current confinement layers, and insulating layers with openings. This segmentation allows independent optimization of each component to control current flow and light emission patterns, reducing beam divergence while maintaining emission efficiency.
Solution Approach 2:
The insulating layer is designed with localized openings positioned over specific columnar semiconductor stack structures, creating non-uniform current distribution. This local quality modification ensures current flows through designated active regions while being blocked in other areas, improving light emission efficiency and controlling beam shape.
2Reliability
If the insulating layer covers the columnar semiconductor stack structures without openings, then current confinement is improved, but light emission is blocked and efficiency decreases
Solution Approach 1:
The insulating layer is segmented with strategic openings that allow light to pass through while maintaining current confinement in specific regions. This segmentation enables the insulating layer to simultaneously perform both current blocking and light transmission functions in different areas.
Solution Approach 2:
The openings in the insulating layer act as intermediaries that mediate between the current confinement requirement and light emission requirement. These openings allow light generated in the active region to pass through the insulating layer to the exterior while the surrounding insulating material continues to confine current flow.
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 design improves light emission efficiency by reducing beam divergence and enhancing coherent radiation output, allowing for more controlled and focused light emission.
Implementation Method 1
Each of the columnar semiconductor stack structures includes a first reflective structure, a cavity region, a second reflective structure
Implementation Method 2
a current confinement layer in the second reflective structure and having a conductive area and an insulating area surrounding the conductive area
Implementation Method 3
An electrical current is injected into the active region through the first electrode and the second electrode to generate the light in the active region
Data Source
AI summary
A semiconductor device includes a substrate having a first side and a second side opposite to the first side; a first optical element at the first side of the substrate; and a semiconductor stack on the substrate. The semiconductor stack includes a first reflective structure; a second reflective structure; a cavity region between the first reflective structure and the second reflective structure and having a first surface and a second surface opposite to the first surface; and a confinement layer in one of the second reflective structure and the first reflective structure. The semiconductor device further includes a first electrode and a second electrode on the first surface.