VCSEL Current Confinement via P-N Junction for Stress Reduction
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Solution Overview
Problem
Conventional vertical cavity surface emitting lasers face issues with high manufacturing costs, difficulty in controlling hole size, internal stress due to lattice mismatch and thermal expansion differences, and susceptibility to electrostatic discharge, which affect reliability and lifespan.
Innovation Solution
A surface emitting laser apparatus with a current confinement structure featuring a P-N junction or PIN junction, or a Zener diode, is used to reduce internal stress and enhance anti-electrostatic capability, incorporating semiconductor materials with minimal lattice mismatch and thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide layer or ion implantation region is formed by ion implantation process or wet oxidation process to confine current, then current confinement is achieved, but manufacturing cost increases and hole size control becomes difficult
Solution Approach 1:
The patent changes the material parameter from oxide layer to semiconductor layer with different conductivity type, and changes the confinement mechanism from chemical/physical modification to electrical field control via P-N junction, achieving better hole size control and lower manufacturing cost
Solution Approach 2:
The patent uses composite structure of semiconductor layers with different conductivity types (P-type and N-type) to create the current confinement structure, replacing the single-material oxide layer approach
2Reliability
If oxide layer is formed on upper DBR to confine current, then current confinement is achieved, but internal stress increases due to lattice mismatch and thermal expansion differences
Solution Approach 1:
The patent changes the material composition from oxide to semiconductor, matching the lattice structure and thermal expansion properties with the surrounding semiconductor layers, thereby eliminating the internal stress caused by lattice mismatch and thermal expansion differences
Solution Approach 2:
The patent uses semiconductor materials throughout the laser structure, ensuring homogeneous material properties and compatible thermal expansion coefficients, which reduces internal stress compared to using oxide layers with dissimilar properties
3Reliability
If conventional oxide layer structure is used, then current confinement is achieved, but anti-electrostatic capability is poor
Solution Approach 1:
The patent changes the electrical parameters by creating a P-N junction structure that provides controlled electrical breakdown characteristics, enabling the structure to safely dissipate electrostatic discharge energy rather than suffering catastrophic failure
Solution Approach 2:
The patent converts the potentially harmful electrostatic discharge into a controlled event by using the P-N junction's breakdown characteristic to safely channel and dissipate the discharge energy, protecting the active layer from damage
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 solution improves the reliability and anti-electrostatic protection of the surface emitting laser apparatus, reducing manufacturing costs and preventing damage from electrostatic discharge while maintaining efficient light emission.
Implementation Method 1
The current confinement structure has one P-N junction or one PIN junction
Implementation Method 2
The current confinement structure includes a Zener diode
Data Source
AI summary
A surface emitting laser apparatus and a method for manufacturing the same are provided. The surface emitting laser apparatus includes a first reflector layer, an active light-emitting layer, a second reflector layer, and a current confinement structure. The active light-emitting layer is disposed between the first reflector layer and the second reflector layer, so as to produce a laser beam. The current confinement structure has one P-N junction or one PIN junction.