GaN Epitaxial Growth Carbon Doping Control
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Solution Overview
Problem
Conventional power electronics face challenges in achieving high voltage capabilities with low resistance and low defect density, particularly in gallium nitride (GaN) semiconductor devices due to background carbon incorporation, which affects dopant concentration and device performance.
Innovation Solution
The method involves controlling the carbon density in GaN semiconductor devices by adjusting the molar ratio of group V to group III elements during epitaxial growth, using techniques such as selective epitaxial growth and metal organic chemical vapor deposition (MOCVD) to reduce carbon incorporation and achieve low dopant concentrations, enabling high breakdown voltages and low resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional epitaxial growth methods are used, then carbon incorporation occurs in GaN layers, but this leads to increased background dopant concentration and reduced device performance
Solution Approach 1:
The patent applies parameter changes by adjusting the molar ratio of group V to group III elements during epitaxial growth to at least 5,000, and controlling carbon concentration to less than 1×10^18 atoms/cm³. This precise parameter control enables low background dopant concentration while maintaining high electron mobility and breakdown voltage, directly resolving the contradiction between manufacturing precision and device reliability
Solution Approach 2:
The patent implements local quality by creating specific regions with different carbon concentrations and doping levels within the GaN device structure. By controlling carbon density locally in the drift region versus other areas, the invention achieves low background dopant concentration where needed while maintaining overall device functionality and high performance
2Loss of energy
If high dopant concentration is used to reduce resistance, then on-state resistance decreases, but breakdown voltage capability is reduced
Solution Approach 1:
The patent resolves this contradiction by changing the carbon concentration parameter to less than 1×10^18 atoms/cm³ and maintaining low background dopant concentration (less than 1×10^16 atoms/cm³). This enables the drift region to achieve both low resistance and high breakdown voltage by eliminating carbon-induced background doping that would otherwise force a trade-off between these parameters
Solution Approach 2:
The patent employs composite material structures with multiple epitaxial layers having different doping concentrations and carbon densities. By combining low-carbon drift regions with appropriately doped contact and barrier layers, the invention achieves both low on-state resistance and high breakdown voltage capability through the synergistic properties of the composite structure
3Area of stationary object
If thick vertical drift layers are grown to achieve high breakdown voltage, then device area is reduced, but background carbon incorporation increases
Solution Approach 1:
The patent applies parameter changes by maintaining carbon concentration at less than 1×10^18 atoms/cm³ during the growth of thick vertical drift layers. By controlling the carbon parameter and V/III ratio at least 5,000, the invention enables growth of thick drift regions needed for high breakdown voltage without the background carbon incorporation that would otherwise occur, thus achieving both small device area and precise carbon concentration control
Solution Approach 2:
The patent implements preliminary action by establishing low carbon concentration conditions and appropriate V/III ratios before growing the thick drift layer. By preparing the epitaxial growth environment with controlled parameters in advance, the invention prevents carbon incorporation during the growth of thick vertical structures, enabling high breakdown voltage with minimal device area
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 approach results in GaN devices with superior properties, including high electron mobility, low defect density, and reduced resistance, allowing for efficient high voltage operation with smaller device area, faster switching, and increased reliability compared to conventional materials.
Implementation Method 1
growing an n-type III-nitride-based epitaxial layer
Implementation Method 2
background carbon incorporation in epitaxial films
Implementation Method 3
metal organic chemical vapor deposition (MOCVD)
Data Source
AI summary
A method of growing an n-type III-nitride-based epitaxial layer includes providing a substrate in an epitaxial growth reactor, forming a masking material coupled to a portion of a surface of the substrate, and flowing a first gas into the epitaxial growth reactor. The first gas includes a group III element and carbon. The method further comprises flowing a second gas into the epitaxial growth reactor. The second gas includes a group V element, and a molar ratio of the group V element to the group III element is at least 5,000. The method also includes growing the n-type III-nitride-based epitaxial layer.