GaN Semiconductor Laser Facet Window via Selective Growth
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Solution Overview
Problem
It is challenging to form a facet window structure in GaN-based semiconductor laser devices using impurity diffusion or ion implantation due to the strong bond between gallium and nitrogen in nitride semiconductors, which prevents effective amorphization and increases the risk of catastrophic optical damage (COD).
Innovation Solution
A semiconductor laser device is manufactured using selective growth with a mask to create a larger forbidden band width portion around the active layer's front facet, forming a facet window structure without impurity diffusion or ion implantation, thereby reducing or preventing COD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If impurity diffusion or ion implantation is used to form a facet window structure, then light absorption at the facet is reduced, but the strong bond between Ga and N prevents effective amorphization in nitride semiconductors
Solution Approach 1:
The patent changes the composition parameters of the active layer by controlling the aluminum content distribution. By making the aluminum content larger at the facet portion compared to the inner portion, the forbidden band width is increased at the facet, reducing light absorption without requiring amorphization. This compositional parameter change achieves the facet window effect in nitride semiconductors where traditional amorphization methods fail.
2Ease of manufacture
If the active layer is uniformly structured, then manufacturing is simplified, but light absorption occurs at the facet portion causing catastrophic optical damage
Solution Approach 1:
The patent applies local quality by creating a non-uniform aluminum content distribution within the active layer. The aluminum content is specifically increased at the facet portion (AlGaInN layer near facet) compared to the inner portion, giving different optical properties to different regions. This local compositional variation reduces light absorption at the facet while maintaining overall structural integrity and manufacturability.
3Power
If high power laser light is extracted from the cavity, then light output is improved, but heat generation at the facet increases causing temperature rise and crystal melting
Solution Approach 1:
The patent changes the compositional parameters of the active layer to increase the aluminum content at the facet portion. This increases the forbidden band width at the facet, reducing optical absorption and consequently reducing heat generation from absorbed laser light. This allows high power operation without excessive temperature rise at the facet that would lead to crystal melting.
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 approach effectively reduces or prevents COD by forming a facet window structure that minimizes light absorption at the facet, allowing for the production of semiconductor laser devices with improved reliability and performance even with nitride semiconductors.
Implementation Method 1
a semiconductor multilayer structure selectively grown on a substrate other than on a predetermined region of the substrate
Data Source
AI summary
A semiconductor laser device includes a semiconductor multilayer structure selectively grown on a substrate other than on a predetermined region of the substrate. The semiconductor multilayer structure includes an active layer, and has a stripe-shaped optical waveguide extending in a direction intersecting a front facet through which light is emitted. The active layer has an abnormal growth portion formed at a peripheral edge of the predetermined region, and a larger forbidden band width portion formed around the abnormal growth portion and having a larger width of a forbidden band than that of a portion other than the abnormal growth portion of the active layer. The optical waveguide is spaced apart from the abnormal growth portion and includes the larger forbidden band width portion at the front facet.