GaN Layered Substrate Transfer with Ga-Polar Surface and High Crystallinity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing GaN layered substrates with good crystallinity and a Ga polar face surface are inefficient, requiring multiple transfer processes, leading to high costs and defects due to warpage and poor crystallinity on N polar faces during epitaxial growth.
Innovation Solution
A method involving high-temperature nitriding treatment and epitaxial growth on a C-plane sapphire substrate with an off-angle, followed by ion implantation and delamination to transfer a GaN thin film onto a support substrate, ensuring a Ga polar face surface with reduced transfer frequency and improved crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If GaN is epitaxially grown directly on a Si substrate, then large-diameter substrates can be produced, but warpage occurs due to thermal expansion coefficient difference requiring thick buffer layers
Solution Approach 1:
The patent introduces an AlN buffer layer as an intermediary between the Si substrate and GaN film. This buffer layer has a thermal expansion coefficient intermediate between Si and GaN, effectively reducing warpage while enabling large-diameter substrate production
2Adaptability or versatility
If the GaN thin film is transferred to ensure a Ga face surface, then device applications become possible, but multiple transfer processes are required increasing complexity and cost
Solution Approach 1:
Instead of growing GaN on a Si substrate and then transferring, the patent inverts the approach by first growing high-quality GaN on an AlN substrate (which naturally provides a Ga face), then transferring this GaN film to the Si substrate. This single transfer process achieves both high crystallinity and Ga face orientation required for device applications
3Stability of the object's composition
If a thick buffer layer is inserted to relax warpage, then substrate stability improves, but GaN layer thickness is limited
Solution Approach 1:
The patent segments the structure into distinct functional layers: an AlN buffer layer on the Si substrate to handle thermal expansion and provide stability, and a separate GaN film layer grown on AlN substrate that can be transferred. This segmentation allows the GaN layer to achieve greater thickness without being constrained by the buffer layer requirements
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
This method allows for the production of GaN layered substrates with a Ga polar face surface in a single transfer process, reducing material loss, cost, and in-plane thickness variation, while maintaining high crystallinity and pressure resistance.
Implementation Method 1
subjecting a C-plane sapphire substrate having an off-angle of 0.5 to 5 degrees to a high-temperature nitriding treatment at 800° C. to 1,000° C.
Implementation Method 2
carrying out epitaxial growth of GaN on the surface of the surface-treated C-plane sapphire substrate
Implementation Method 3
forming an ion implantation region by carrying out ion implantation on the GaN film
Data Source
AI summary
Provided is a method for producing a GaN layered substrate, comprising the steps of: subjecting a C-plane sapphire substrate 11 having an off-angle of 0.5° to 5° to a high-temperature nitriding treatment at 800° C. to 1,000° C. to carry out a surface treatment of the C-plane sapphire substrate; carrying out epitaxial growth of GaN on the surface of the surface-treated C-plane sapphire substrate 11 to produce a GaN film carrier having a surface of an N polar face; forming an ion implantation region 13ion by carrying out ion implantation on the GaN film 13; laminating and joining a support substrate 12 with the GaN film-side surface of the ion-implanted GaN film carrier; and separating at the ion-implanted region 13ion in the GaN film 13 to transfer a GaN thin film 13a onto the support substrate 12, to produce a GaN layered substrate 10 having, on the support substrate 12, a GaN thin film 13a having a surface of a Ga polar face. A GaN layered substrate having a good crystallinity and a surface of a Ga face is obtained by a single transfer process.