VCSEL Tunnel Junction Layout for Common-Anode High-Speed Driving
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Solution Overview
Problem
Conventional VCSELs are limited by their cathode-anode configuration, which hinders the use of high-speed N-type transistors and common-anode driving, restricting their application in high-frequency and high-speed driving fields.
Innovation Solution
The VCSEL design includes an N-type substrate with an anode on the backside and a cathode on the frontside, utilizing tunnel junctions to reverse carrier types, allowing for common-anode driving and enabling high-speed N-type transistor operation, along with optimized DBR layers to reduce warpage and improve light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional cathode-anode configuration is used in VCSEL, then the basic laser function is achieved, but high-speed N-type transistor operation and common-anode driving are hindered
Solution Approach 1:
The patent inverts the conventional cathode-anode configuration by placing the anode on the front side and cathode on the back side of the VCSEL. This inversion enables common-anode driving and high-speed N-type transistor operation, directly resolving the limitation of conventional configurations
2Speed
If tunnel junctions are added to reverse carrier types, then high-speed driving capability is enabled, but device structure becomes more complex
Solution Approach 1:
The tunnel junctions serve multiple functions: they reverse carrier types to enable high-speed operation, facilitate common-anode driving, and maintain laser performance. This multi-functionality justifies the added structural complexity
3Manufacturing precision
If DBR layers are optimized to reduce warpage, then manufacturing quality is improved, but device structure becomes more complex
Solution Approach 1:
The patent optimizes specific DBR layer properties (refractive indices, thicknesses, material compositions) at critical locations to reduce warpage while maintaining overall structural simplicity. The optimization focuses on the relationship between upper DBR and lower DBR layers
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 high-frequency and high-speed driving capabilities while reducing the driver system size, enhancing light emission efficiency and quality, and facilitating the use of N-type transistors with higher response speed.
Implementation Method 1
The first tunnel junction is configured to reverse carriers in the N-type buffer layer to carriers of opposite conductivity type. The second tunnel junction is configured to reverse carriers in the upper DBR to carriers of opposite conductivity type.
Implementation Method 2
an upper distributed Bragg reflector (DBR), an N-type buffer layer, a first tunnel junction, a P-type DBR
Implementation Method 3
Distributed Bragg Reflectors (DBRs) that have a function of optical feedback
Implementation Method 4
the active layer includes an object stacked structure. The object stacked structure includes a P-type semiconductor layer, a quantum well layer, and an N-type semiconductor layer sequentially stacked
Implementation Method 5
The quantum well layer includes at least one quantum well
Data Source
AI summary
Disclosed are a vertical-cavity surface-emitting laser (VCSEL), a laser array, and a light-emitting device. The VCSEL includes an N-type substrate and an upper distributed Bragg reflector (DBR), and an N-type buffer layer, a first tunnel junction, a P-type DBR, an active layer, a second tunnel junction, a P-type metal contact layer, and a cathode electrode stacked sequentially along a direction perpendicular to a front side of the N-type substrate and arranged on the front side of the N-type substrate. The first tunnel junction is configured to reverse carriers in the N-type buffer layer to carriers of opposite conductivity type. The second tunnel junction is configured to reverse carriers in the upper DBR to carriers of opposite conductivity type. The upper DBR is positioned between the active layer and the P-type metal contact layer. An anode electrode is arranged on a back side of the N-type substrate.