GaN Surface-Emitting Laser Photonic Crystal With Uniform Hole Embedding
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Solution Overview
Problem
Conventional methods for manufacturing photonic-crystal surface-emitting lasers result in nonuniform air holes, leading to increased optical loss and higher oscillation threshold current density due to variations in air-hole sizes and shapes within the photonic crystal layer.
Innovation Solution
A manufacturing method involving MOVPE for GaN-based semiconductors, where a first cladding layer is grown, followed by a guide layer with periodically arranged holes, and then an embedding layer is formed to close these holes, resulting in a photonic crystal layer with air holes of extremely uniform size, specifically a unimodal distribution with a standard deviation of 1 nm or less, to reduce scattering loss and achieve low threshold current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If SiO2 is deposited at the bottom of the air holes for growth inhibition, then the air holes can be formed in the photonic crystal layer, but nonuniformity in the coverage of SiO2 causes nonuniform air-hole sizes
Solution Approach 1:
The patent removes the SiO2 deposition step entirely and replaces it with a direct embedding layer formation process using MOVPE. By extracting the problematic intermediate step (SiO2 deposition) and replacing it with a single-step embedding layer formation, the patent eliminates the source of nonuniformity while maintaining the functional requirement of hole embedding.
Solution Approach 2:
The patent changes the deposition method from sequential SiO2 deposition to direct embedding layer formation using MOVPE with specific parameter control (temperature, pressure, gas flow). By changing the process parameters and method, the patent achieves uniform coverage without the nonuniformity issues of the previous approach.
2Reliability
If air holes are formed with varying sizes and shapes, then the photonic crystal structure can be created, but the periodicity of the refractive index distribution is disturbed causing light scattering and increased optical loss
Solution Approach 1:
The patent uses gas-phase transport (pneumatic approach) in MOVPE to deliver precursors uniformly to the substrate surface. The gas flow dynamics and pressure control ensure uniform precursor distribution, leading to uniform embedding layer deposition and uniform air-hole sizes, thereby maintaining refractive index periodicity and reducing light scattering.
Solution Approach 2:
The patent optimizes MOVPE parameters (temperature, pressure, gas flow rates, precursor ratios) to achieve uniform embedding layer formation. By carefully controlling these parameters, the patent ensures uniform air-hole sizes and shapes, maintaining the periodicity of the refractive index distribution and minimizing optical loss.
3Power
If the resonator loss increases due to nonuniform air holes, then the photonic crystal layer can be formed, but the oscillation threshold current density increases significantly
Solution Approach 1:
The patent extracts and removes the source of resonator loss (nonuniform air holes) by eliminating the SiO2 deposition step that caused nonuniform coverage. This directly reduces resonator loss and enables lower threshold current density operation.
Solution Approach 2:
The patent changes the embedding layer formation process to MOVPE with optimized parameters, achieving uniform air-hole sizes that maintain resonator quality. This parameter optimization reduces resonator loss and enables the laser to operate at lower threshold current densities.
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 method ensures highly uniform air-hole sizes in the photonic crystal layer, significantly reducing scattering loss and allowing the laser to oscillate at a lower threshold current density, enhancing the quality and crystallinity of the active layer and improving the laser's performance.
Implementation Method 1
supplying a gas containing a nitrogen source to cause mass transport without supplying a group-III material gas, and then supplying the group-III material gas for growth, whereby a first embedding layer closing openings of the holes is formed
Implementation Method 2
A manufacturing method involving MOVPE for GaN-based semiconductors
Implementation Method 3
supplying a gas containing a nitrogen source to cause mass transport without supplying a group-III material gas
Data Source
AI summary
A method for manufacturing a GaN-based surface-emitting laser by an MOVPE includes: (a) growing a first cladding layer with a {0001} growth plane; (b) growing a guide layer on the first cladding layer; (c) forming holes in a surface of the guide layer by etching, the holes being two-dimensionally periodically arranged within a plane parallel to the guide layer; (d) etching the guide layer by using an etchant having selectivity to the {0001} plane and a {10−10} plane of the guide layer; (e) supplying a gas containing a nitrogen source to cause mass transport without supplying a group-III material gas, and then supplying the group-III material gas for growth, whereby a first embedding layer closing openings of the holes is formed to form a photonic crystal layer; and (f) growing an active layer and a second cladding layer in this order on the first embedding layer.