VCSEL Tunnel Junction Oxidation for Low-Cost Current Confinement
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Solution Overview
Problem
Existing VCSEL devices face challenges in producing a current confinement structure on InP substrates due to lattice-matching issues with AlAs oxidized layers, leading to high production costs and crystal deterioration, particularly when using AlInAs oxidized layers, which require molecular beam epitaxy and high-temperature oxidation.
Innovation Solution
A VCSEL device with a tunnel junction layer that includes a highly doped AlInAs layer, where the outer peripheral region is oxidized to form an insulating layer, allowing for a current confinement structure through selective oxidation at lower temperatures, reducing crystal deterioration and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If AlInAs oxidized layer is used for current confinement structure on InP substrate, then lattice matching is achieved, but high-temperature oxidation is required causing crystal deterioration
Solution Approach 1:
The patent changes the oxidation temperature parameter from high temperature (conventional method) to low temperature (below 400°C), enabling oxidation of AlInAs layer without causing crystal deterioration while maintaining lattice matching between AlInAs and InP substrate
Solution Approach 2:
The patent uses a composite structure consisting of AlInAs layer combined with other materials (such as tunnel junction layers with different Al compositions) to achieve both lattice matching and effective current confinement through selective oxidation at low temperatures
2Reliability
If buried tunnel junction is used for current confinement structure on InP substrate, then current confinement is achieved, but crystal re-growth is required increasing production cost
Solution Approach 1:
The patent extracts the oxidation process from the high-temperature regime and performs it at low temperatures after epitaxial growth, eliminating the need for crystal re-growth while maintaining effective current confinement through the oxidized AlInAs layer
Solution Approach 2:
The patent performs preliminary oxidation of the AlInAs layer at low temperature after the epitaxial growth is complete, avoiding the need for additional crystal re-growth steps and reducing production costs while achieving current confinement
3Manufacturing precision
If AlInAs layer with low Al composition is used for lattice matching, then lattice matching with InP substrate is achieved, but oxidation rate decreases requiring high-temperature oxidation
Solution Approach 1:
The patent changes the oxidation temperature parameter to low temperature and compensates for the low oxidation rate by extending the oxidation time, thereby achieving effective current confinement without requiring high-temperature oxidation that would damage the crystal structure
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 method enables the production of a VCSEL device with a current confinement structure efficiently, reducing production costs and maintaining crystal integrity by using a producible method that allows for selective oxidation at lower temperatures.
Implementation Method 1
the tunnel junction layer includes a first highly doped layer and a second highly doped layer, an outer peripheral region of each of the first highly doped layer and the second highly doped layer is oxidized to form an insulating layer
Data Source
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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.