3D GaN Epitaxial Structure Growth via Plasma Nitrogen and Gallium Vapor
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Solution Overview
Problem
Conventional methods for growing GaN structures, such as MOCVD and MBE, face challenges in controlling film thickness and quality, leading to low luminous intensity in large-sized GaN thin films and difficulties in connecting electrodes due to small diameters of GaN nanopillars, which complicates the manufacturing process.
Innovation Solution
A method for forming a three-dimensional GaN epitaxial structure using a LiAlO2 substrate and Ga source in an ultra-high vacuum chamber, with N ions in a plasma state reacting with Ga vapor at controlled temperatures between 600° C. and 750° C., and a N/Ga flux ratio of 20-40, resulting in a hexagonal micropyramid or hexagonal rod with a broadened disk-like surface for easier electrode connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If MOCVD method is used to form large-sized GaN thin film, then large area coverage is achieved, but film thickness control and manufacturing quality become difficult
Solution Approach 1:
The patent transitions from conventional planar (2D) thin film growth to three-dimensional (3D) nanorod/nanopillar structure growth. This dimensional change enables precise thickness control through the vertical growth dimension while maintaining large area coverage through the horizontal arrangement of multiple nanorods, thereby resolving the contradiction between area coverage and thickness control precision.
Solution Approach 2:
The patent segments the continuous thin film into discrete nanorod or nanopillar structures. Each nanorod can be independently controlled in terms of height and diameter, allowing precise thickness control at the nanoscale while maintaining large area coverage through the collective arrangement of numerous segmented structures.
2Quantity of substance
If MBE method is used to form GaN nanopillar with small diameter, then high density structures are achieved, but electrode connection becomes difficult
Solution Approach 1:
The patent applies local quality by creating structures with varying diameters along the vertical axis - narrower at the base for high density packing and wider at the top for easy electrode connection. This local variation in geometric quality allows the structure to simultaneously achieve high density arrangement and facile electrode attachment.
Solution Approach 2:
By transitioning to 3D nanorod/nanopillar structures with controlled aspect ratios, the patent adds the vertical dimension for electrode access while maintaining horizontal density. The vertical growth dimension provides a pathway to reach electrode connection points without compromising the horizontal packing density.
3Adaptability or versatility
If GaN structure is grown on substrate with large lattice mismatch, then growth on common substrates is enabled, but dislocation and defects increase
Solution Approach 1:
The patent uses 3D nanorod/nanopillar growth to accommodate lattice mismatch by allowing dislocations to terminate at the nanorod sides or propagate vertically rather than laterally across a continuous film. This dimensional approach enables growth on common substrates like Si while maintaining lower defect densities in the active regions.
Solution Approach 2:
By segmenting the film into discrete nanorods, the patent isolates defects within individual structures. Dislocations and defects are confined to specific nanorods rather than propagating across the entire film, thereby maintaining overall device reliability while enabling growth on substrates with lattice mismatch.
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 enhances luminous intensity and simplifies electrode connection by forming a GaN epitaxial structure with a wider surface area, reducing defects and manufacturing complexity compared to conventional methods.
Implementation Method 1
N ions in a plasma state reacting with Ga vapor at controlled temperatures between 600°C and 750°C
Implementation Method 2
N ions in a plasma state
Implementation Method 3
heating up the source metal to generate Ga vapor
Implementation Method 4
N ions in a plasma state generated by a nitrogen source
Data Source
AI summary
A manufacturing method for three-dimensional GaN epitaxial structure comprises a disposing step, in which a substrate of LiAlO2 and a source metal of Ga are disposed inside an vacuum chamber. An exposing step is importing N ions in plasma state and generated by a nitrogen source into the chamber. A heating step is heating up the source metal to generate Ga vapor. A growing step is forming a three-dimensional GaN epitaxial structure with hexagonal micropyramid or hexagonal rod having a broadened disk-like surface on the substrate by reaction between the Ga vapor and the plasma state of N ions.