VCSEL Cavity Structure for Low Threshold Current and High Efficiency
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Solution Overview
Problem
Conventional vertical cavity light-emitting elements face challenges in reducing threshold current and improving light emission efficiency.
Innovation Solution
The design incorporates specific layer thicknesses and refractive indices for the active and final barrier layers, along with a dielectric spacer layer, to optimize the standing wave conditions within the electron blocking and p-type semiconductor layers, ensuring that the number of antinodes and nodes is zero or one, which enhances carrier uniformity and optical gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional vertical cavity light-emitting element structures are used, then basic light emission function is achieved, but threshold current is high and light emission efficiency is low
Solution Approach 1:
The patent applies parameter changes by precisely controlling the layer thicknesses of the active layer (Hqw) and final barrier layer (Hfb) relative to the standing wave wavelength, and by adjusting refractive indices (nqw, nfb) through material composition optimization. These parameter optimizations enable the cavity to resonate at the desired wavelength with minimal loss, reducing threshold current and improving light emission efficiency
Solution Approach 2:
The patent implements local quality by creating specific optical field distributions within different layers of the device. By ensuring that the electron blocking layer and p-type semiconductor layer contain zero or one antinodes and nodes, the patent locally optimizes the optical field concentration in the active region while maintaining appropriate carrier confinement in the blocking region, thereby simultaneously improving efficiency and reducing threshold current
2Reliability
If layer thicknesses and refractive indices are optimized for standing wave conditions, then carrier uniformity and optical gain are enhanced, but device structure complexity increases
Solution Approach 1:
The patent maintains reliability by optimizing key parameters including the thickness ratio Hfb/Hqw and refractive index ratio nfb/nqw, while controlling the number of antinodes and nodes in specific layers. These targeted parameter changes achieve carrier uniformity and high optical gain without requiring complex multi-layer structures, thus limiting the increase in 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 results in a vertical cavity light-emitting element with a low threshold current and high light emission efficiency, characterized by improved carrier uniformity and reduced internal loss, leading to efficient surface emitting lasers.
Implementation Method 1
a light-emitting element that emits light in a direction vertical to the substrate surface
Implementation Method 2
a structure in which light is resonated vertically to a substrate surface and light is emitted in a direction vertical to the substrate surface
Implementation Method 3
a multiple quantum well (MQW) structure is generally adopted for an active layer
Data Source
AI summary
The present invention includes an n-type semiconductor layer formed on a first reflective mirror, an active layer made of multiple quantum wells formed on the n-type semiconductor layer, a final barrier layer formed on the final quantum well of the active layer, an electron blocking layer formed on the final barrier layer, a p-type semiconductor layer formed on the electron blocking layer, a dielectric spacer layer formed on the p-type semiconductor layer, and a second reflective mirror formed on the spacer layer. The number of antinodes of a standing wave due to emitted light from the active layer, included in the electron blocking layer and the p-type semiconductor layer is 1, the number of nodes is 0 or 1, and Expression (3) is satisfied for the active layer and the final barrier layer.