GaN Laminated Structure Mg Activation via Protective Layering
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Solution Overview
Problem
The existing manufacturing method for GaN devices results in inactive Mg in the p-type GaN layer due to H2 bonding, leading to increased resistance and difficulty in achieving high current and normally-off operation, which are essential for power devices.
Innovation Solution
A method involving the formation of an n-type or i-type first layer, a p-type second layer with Mg, and an n-type or i-type third layer without activation annealing, ensuring Mg remains active and reducing resistance, allowing for the creation of a nitride semiconductor laminated structure suitable for high-current power devices with a normally-off operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the p-type GaN layer is laminated in an H2 atmosphere, then the lamination process can be completed, but H2 mixes into the layer and bonds with Mg, inactivating the acceptor and increasing resistance
Solution Approach 1:
The patent applies preliminary action by forming the p-type GaN layer with Mg doping first, then immediately covering it with an n-type or i-type GaN layer before H2 can diffuse and bond with the Mg atoms. This sequence prevents H2 contamination of the Mg acceptors while maintaining the p-type characteristics, eliminating the need for subsequent activation annealing that would otherwise be required to restore Mg functionality.
Solution Approach 2:
The patent skips the traditional activation annealing step by rushing through the lamination process immediately after forming the p-type layer. By quickly depositing the protective n-type or i-type layer, the process bypasses the period during which H2 could bond with Mg and inactivate it, thereby maintaining low resistance without requiring the time-consuming activation annealing treatment.
2Reliability
If activation annealing is performed to activate Mg, then Mg functions as an acceptor, but the process complexity and time increase
Solution Approach 1:
The patent performs the protective action preliminarily by covering the Mg-doped p-type layer with an n-type or i-type layer immediately after formation. This preliminary protective layer prevents H2 from bonding with Mg, so the Mg remains naturally active without requiring subsequent activation annealing, thus maintaining productivity while ensuring reliable acceptor function.
3Reliability
If the p-type GaN layer is formed with Mg doping, then it can provide p-type conductivity, but H2 bonding inactivates the Mg and increases layer resistance
Solution Approach 1:
The patent introduces an intermediary n-type or i-type GaN layer that acts as a protective barrier between the H2 atmosphere and the Mg-doped p-type layer. This intermediary layer prevents H2 from reaching and bonding with the Mg atoms, thereby preserving the p-type conductivity and maintaining low resistance without requiring additional activation steps.
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 enables the production of GaN devices with reduced resistance, high current handling, and reliable normally-off operation, enhancing their suitability for power devices by maintaining Mg in an active state and eliminating the need for activation annealing, thereby improving mass productivity.
Implementation Method 1
the p-type GaN layer is first laminated on the sapphire substrate in an H2 atmosphere by epitaxially growing a GaN-based semiconductor compound
Data Source
AI summary
A method for forming a nitride semiconductor laminated structure includes forming a first layer that is an n-type or i-type first layer composed of a group III nitride semiconductor using an H2 carrier gas; forming a second layer by laminating a p-type second layer composed of a group III nitride semiconductor and containing Mg on the first layer using an H2 carrier gas; and forming a third layer that is an n-type or i-type third layer composed of a group III nitride semiconductor on the second layer using an H2 carrier gas after forming the second layer. A method for manufacturing a nitride semiconductor device includes the method steps for forming the nitride semiconductor laminated structure.