VCSEL Tunnel Junction Oxide Structure for Low-Cost Current Confinement
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Solution Overview
Problem
The production of vertical cavity surface emitting lasers (VCSELs) with current confinement structures on InP substrates is costly due to the need for crystal re-growth and requires high-temperature oxidation, which can lead to crystal deterioration, and the producibility of AlInAs oxidized layers is challenging due to low Al composition and oxidation rate.
Innovation Solution
A VCSEL device with a mesa structure featuring a tunnel junction layer having an insulating outer peripheral region, where the inner peripheral region is formed of Al-containing material and the outer peripheral region is formed of Al oxide, allowing current confinement and reducing production costs through selective oxidation and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a buried tunnel junction is used for current confinement structure on InP substrate, then current confinement is achieved, but crystal re-growth is required which increases production cost
Solution Approach 1:
The tunnel junction layer is divided into an inner peripheral region (non-oxidized, Al-containing semiconductor material) and an outer peripheral region (oxidized, insulating Al oxide), creating segmented functional zones within a single layer structure. This segmentation enables current confinement without requiring crystal re-growth, as the oxidized outer region provides electrical isolation while the inner region maintains tunneling current flow.
Solution Approach 2:
Different regions of the tunnel junction layer are given different properties: the inner peripheral region retains semiconductor properties for current conduction, while the outer peripheral region is oxidized to provide insulating properties. This local differentiation of material properties achieves current confinement functionality without the need for complex re-growth processes.
2Stability of the object's composition
If AlInAs oxidized layer is used for current confinement structure, then lattice matching with InP substrate is achieved, but high-temperature oxidation is required which leads to crystal deterioration
Solution Approach 1:
The oxidation process parameters are changed from high-temperature to low-temperature conditions. By conducting oxidation at lower temperatures, the patent avoids crystal deterioration while still achieving sufficient oxidation of the outer peripheral region to create the insulating barrier for current confinement.
3Stability of the object's composition
If AlInAs layer with low Al composition is used for current confinement, then lattice matching with InP substrate is achieved, but oxidation rate decreases requiring high-temperature oxidation
Solution Approach 1:
The patent changes the oxidation process parameters from high-temperature to low-temperature conditions. By conducting oxidation at lower temperatures, the patent avoids crystal deterioration while still achieving sufficient oxidation of the outer peripheral region to create the insulating barrier for current confinement.
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 enables efficient current confinement and reduces production costs by allowing for a producible method that avoids high-temperature oxidation, maintaining crystal integrity and improving the VCSEL's performance and manufacturing efficiency.
Implementation Method 1
the outer peripheral region being formed of a material containing an Al oxide
Data Source
AI summary
[Object] To provide a vertical cavity surface emitting laser device that is excellent in producibility and capable of reducing the production cost and a method of producing the vertical cavity surface emitting laser device. [Solving Means] A vertical cavity surface emitting laser device (100) according to the present technology includes: a first reflection mirror (103); a second reflection mirror (109); a first semiconductor layer (104); a second semiconductor layer (106); a tunnel junction layer (107); and a light-emitting layer (105), the vertical cavity surface emitting laser device (100) having a mesa structure (M) that has a current injection region where a current passing through an inner peripheral region and flowing into the light-emitting layer (105) concentrates. The tunnel junction layer (107) is disposed between the first reflection mirror (103) and the second reflection mirror (109), a highly doped layer (122) of a first conductivity type and a highly doped layer (121) of a second conductivity type being joined together in the tunnel junction layer (107), the tunnel junction layer (107) having an inner peripheral region on an inner peripheral side when viewed from a direction perpendicular to a layer surface and an outer peripheral region surrounding the inner peripheral region, the inner peripheral region being formed of a material containing Al, the outer peripheral region being formed of a material containing an Al oxide. The light-emitting layer (105) is disposed between the first reflection mirror (103) and the second reflection mirror (109) and emits light by carrier recombination.