VCSEL Light-Emitting Device Current Blocking Layer Design
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Solution Overview
Problem
Conventional light-emitting devices with vertical cavity surface emitting lasers (VCSELs) face challenges in achieving a narrow far-field angle due to highly resistive structures like oxidized layers and ion implanted regions, which affect their coherence and efficiency.
Innovation Solution
A light-emitting device design that eliminates highly resistive structures by using a current blocking layer and a specific electrode configuration, allowing for coherent and incoherent light emission with controlled current flow, resulting in a far-field angle of less than 15 degrees between the lasing threshold and saturation currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If highly resistive structures like oxidized layers and ion implanted regions are used in VCSELs, then current confinement is improved, but coherence and efficiency deteriorate due to increased resistance
Solution Approach 1:
The patent removes highly resistive structures (oxidized layers and ion implanted regions) from the VCSEL structure and replaces them with a current blocking layer made of semiconductor material. This extraction eliminates the harmful resistance while maintaining current confinement through the epitaxially grown current blocking layer that integrates seamlessly with the surrounding semiconductor layers.
Solution Approach 2:
The patent changes the material parameter of the current blocking structure from highly resistive materials (oxides, ion-implanted regions) to semiconductor material with controlled resistivity. The current blocking layer is formed by epitaxial growth with specific doping levels that provide adequate current blocking while maintaining low resistance, thus resolving the contradiction between current confinement and energy loss.
2Ease of manufacture
If conventional VCSEL structures with highly resistive structures are used, then manufacturing is simplified, but far-field angle control deteriorates (cannot achieve narrow angle less than 15 degrees)
Solution Approach 1:
The patent achieves narrow far-field angle control by precisely controlling the resistivity parameter of the current blocking layer through epitaxial growth and doping. By adjusting the doping concentration and layer thickness during epitaxial growth, the far-field angle is controlled to be less than 15 degrees, achieving both ease of manufacture through epitaxial integration and precision in angular control.
3Loss of energy
If multiple processing steps are added to eliminate highly resistive structures, then coherence and efficiency are improved, but device complexity increases
Solution Approach 1:
The patent merges the current blocking function with the epitaxial growth process. The current blocking layer is formed in-situ during epitaxial growth of the semiconductor layers, combining multiple functions (current blocking, optical confinement, and structural integrity) into a single integrated layer. This eliminates the need for separate oxidation or ion implantation steps, improving coherence and efficiency without significantly increasing 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
The device achieves improved coherence and efficiency by controlling current flow and eliminating resistive structures, making it suitable for applications like sensors and night vision systems.
Implementation Method 1
each of the first radiation emitting region and the second emitting region comprises epitaxial structure comprising a first DBR stack, a light-emitting structure, and a second DBR stack
Implementation Method 2
a first radiation emitting region capable of emitting coherent light and emits a coherent light when driven by a first current
Implementation Method 3
a light-emitting structure... a second radiation emitting region capable of emitting coherent light and emits an incoherent light when driven by the first current
Implementation Method 4
each of the first radiation emitting region and the second emitting region comprises epitaxial structure comprising a first DBR stack, a light-emitting structure, and a second DBR stack
Data Source
AI summary
A light-emitting device is provided. The light-emitting device comprises: a substrate; and multiple radiation emitting regions arranged on the substrate, and comprising: a first radiation emitting region capable of emitting coherent light and emits a coherent light when driven by a first current; a second radiation emitting region capable of emitting coherent light and emits an incoherent light when driven by the first current, wherein each of the first radiation emitting region and the second emitting region comprises epitaxial structure comprising a first DBR stack, a light-emitting structure, and a second DBR stack.