Ridge Laser Diode Cladding Structure for Adhesion and Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
GaN-based laser diodes with edge emitting ridge waveguide structures face issues of poor adhesion between the optical cladding layer and the p-type semiconductor layer, leading to peeling, electrical leakage, and inadequate light field confinement, which affects the device's performance.
Innovation Solution
A laser diode design featuring a substrate with an epitaxial structure forming a ridge structure, an electrode contacting layer, and an optical cladding layer with a first cladding portion covering the side walls and a second cladding portion on the top surface, where the optical cladding layer has a refractive index smaller than the electrode contacting layer, enhancing light confinement and reducing the risk of peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical cladding layer is disposed on the ridge structure to provide light field limitation, then the light confinement is improved, but the adhesion between the cladding layer and p-type semiconductor layer deteriorates leading to peeling and electrical leakage
Solution Approach 1:
The optical cladding layer is segmented into a first cladding portion covering side walls of the ridge structure and a second cladding portion disposed on a portion of the top surface. This segmentation allows the cladding layer to provide light confinement through the side wall coverage while reducing adhesion stress by limiting top surface coverage, thereby preventing peeling and electrical leakage
Solution Approach 2:
The cladding layer is applied selectively to different regions with different functions: the first cladding portion on side walls provides optical confinement, while the second cladding portion on the top surface is limited in area to maintain good adhesion. This local quality differentiation resolves the contradiction between light confinement and adhesion strength
2Reliability
If the metal layer entirely covers the top surface of the ridge structure, then the electrical connection is improved, but the light field distribution becomes unbalanced
Solution Approach 1:
The metal layer is configured with local quality differentiation: it provides complete electrical connection on the side walls through the first cladding portion coverage, while the second cladding portion on the top surface is limited in area to allow balanced light field distribution. This resolves the contradiction between electrical connection reliability and light field uniformity
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 design improves light output efficiency, reduces electrical leakage, and extends the service life of the laser diode by providing better protection and balanced light field distribution through improved current diffusion and optical efficiency.
Implementation Method 1
The optical cladding layer has a refractive index smaller than that of the electrode contacting layer
Implementation Method 2
The p-type semiconductor layer is formed with a ridge structure 31 by inductively coupled plasma (ICP) etching
Data Source
AI summary
A laser diode includes a substrate, an epitaxial structure, an electrode contacting layer and an optical cladding layer. The epitaxial structure is disposed on the substrate, and is formed with a ridge structure opposite to the substrate. The electrode contacting layer is disposed on a top surface of the ridge structure. The optical cladding layer has a refractive index smaller than that of the electrode contacting layer The optical cladding layer includes a first cladding portion which covers side walls of the ridge structure, and a second cladding portion which is disposed on a portion of the top surface of the ridge structure. A method for manufacturing the abovementioned laser diode is also disclosed.