Semipolar III-Nitride Laser With InGaN Step for Fractured Facet Control
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Solution Overview
Problem
Existing Group III nitride semiconductor laser devices face challenges in achieving high lasing yield due to the formation of damaged end faces from dry etching and restrictions on laser stripe orientation, which limits the selection of extending directions and results in poor perpendicularity and flatness of optical cavity facets.
Innovation Solution
A Group III nitride semiconductor laser device with a semipolar primary surface and a semiconductor region including a first and second fractured face, where the InGaN layer has a step at its end face to guide the direction of the fractured face and improve perpendicularity, and the c-axis of the hexagonal nitride semiconductor is inclined at specific angles to prevent deviation from ideal directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dry etching is used to form end faces for the optical cavity, then the fabrication process can be completed, but damaged end faces are formed reducing lasing yield
Solution Approach 1:
The patent extracts the harmful dry etching process from the fabrication sequence by forming end faces through mechanical breaking instead. This removes the source of damage while maintaining the ability to complete the fabrication process, thereby resolving the contradiction between ease of manufacture and reliability.
Solution Approach 2:
The patent employs a sacrificial InGaN layer that is intentionally designed to be broken during the mechanical breaking process. This disposable layer facilitates the formation of clean end faces without requiring complex or damaging processing steps, improving both manufacturability and lasing yield.
2Ease of manufacture
If cleaved facets are used as end faces for the optical cavity, then fabrication can be simplified, but the laser stripe orientation is restricted to cleaving directions
Solution Approach 1:
The patent performs preliminary action by forming a step structure in the InGaN layer before the mechanical breaking process. This pre-formed step guides the breaking direction and enables the laser stripe to be oriented in directions different from traditional cleaving directions, thus maintaining fabrication simplicity while increasing orientation versatility.
Solution Approach 2:
The patent applies local quality by creating a localized step structure in the InGaN layer at specific positions. This local modification enables controlled breaking directions without affecting the overall simplicity of the fabrication process, allowing flexible laser stripe orientation while maintaining ease of manufacture.
3Adaptability or versatility
If the laser waveguide extends in a direction different from cleavable crystal axes, then design flexibility is improved, but cleaved facets cannot be used as end faces requiring better linearity at edges
Solution Approach 1:
The patent performs preliminary action by forming a step structure in the InGaN layer before mechanical breaking. This pre-formed step acts as a guide that ensures high edge linearity during the breaking process, enabling the use of non-cleaved facets for waveguides oriented in directions different from crystal axes without sacrificing manufacturing precision.
Solution Approach 2:
The patent introduces the step structure as an intermediary element that mediates between the desired waveguide orientation and the breaking process. This intermediary feature guides the mechanical breaking to produce highly linear edges, enabling design flexibility while maintaining manufacturing precision.
4Reliability
If mechanical breaking is used to form end faces, then dry etching damage is avoided, but the perpendicularity and flatness of end faces may deviate from ideal directions
Solution Approach 1:
The patent applies local quality by forming a localized step structure in the InGaN layer that serves as a guide for the mechanical breaking process. This local feature ensures that the breaking occurs in a controlled manner, maintaining high perpendicularity and flatness of end faces while avoiding etching damage.
Solution Approach 2:
The patent changes the physical state and structural parameters of the InGaN layer by forming a step structure with specific height and position. This parameter modification controls the breaking behavior during mechanical fracture, ensuring ideal perpendicularity and flatness of end faces while avoiding the damage associated with dry etching.
Data Source
AI summary
A Group III nitride semiconductor laser device includes a laser structure including a support substrate with a semipolar primary surface of a hexagonal Group III nitride semiconductor, and a semiconductor region thereon, and an electrode, provided on the semiconductor region, extending in a direction of a waveguide axis in the laser device. The c-axis of the nitride semiconductor is inclined at an angle ALPHA relative to a normal axis to the semipolar surface toward the waveguide axis direction. The laser structure includes first and second fractured faces intersecting with the waveguide axis. A laser cavity of the laser device includes the first and second fractured faces extending from edges of first and second faces. The first fractured face includes a step provided at an end face of an InGaN layer of the semiconductor region and extending in a direction from one side face to the other of the laser device.