Fe-Doped GaN Buffer Layer for Leak Current Control
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Solution Overview
Problem
Existing semiconductor element manufacturing methods face challenges in reducing leak current and crystal grain boundaries due to surface roughness, particularly when using AlGaN or GaN layers doped with Fe, which affect the heat conductivity and crystallinity of the channel layer.
Innovation Solution
A method involving epitaxial growth of AlN, AlxGayInzN buffer and resistance layers, where x, y, and z satisfy x+y+z=1, with controlled Fe addition to the resistance layer to diffuse Fe into the buffer layer, reducing leak current and surface roughness while maintaining high resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AlGaN layer is formed to limit leak current, then leak current is reduced, but heat conductivity is reduced due to need to select low Al composition ratio
Solution Approach 1:
A GaN layer doped with Fe is introduced as an intermediary layer between the AlN layer and the nitride semiconductor layer. This Fe-doped GaN layer serves as a mediator that provides high resistance to limit leak current while maintaining high heat conductivity, as Fe doping in GaN does not significantly reduce heat conductivity unlike Al doping in AlGaN. The intermediary layer thus resolves the contradiction between leak current control and heat conductivity maintenance.
2Reliability
If GaN layer with Fe is formed between AlN layer and nitride semiconductor layer, then leak current is controlled through high resistance, but crystal grain boundaries increase and surface roughens
Solution Approach 1:
The concentration of Fe doping in the GaN layer is optimized to achieve high resistance for leak current control while minimizing the formation of crystal grain boundaries. By carefully controlling the Fe doping parameter, the layer maintains sufficient resistance without excessive three-dimensional growth that would cause surface roughening and dislocation formation.
3Reliability
If irregularities exist in AlN layer surface, then Fe-doped GaN layer grows three-dimensionally causing dislocations, but without Fe doping leak current cannot be controlled
Solution Approach 1:
Fe doping is applied locally in the GaN layer rather than uniformly throughout the entire semiconductor structure. The Fe-doped GaN layer is positioned specifically between the AlN layer and the nitride semiconductor layer where high resistance is needed for leak current control, while other regions maintain undoped or differently doped compositions to preserve crystallinity and avoid excessive three-dimensional growth.
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 effectively reduces leak current and crystal grain boundaries, enhancing the semiconductor element's performance by controlling the Fe concentration at the interface and maintaining high resistance values, thus improving the semiconductor element's output and withstand voltage.
Implementation Method 1
AlGaInN is epitaxially grown on a substrate formed of sapphire, SiC or Si by metal organic chemical vapor deposition (MOCVD)
Implementation Method 2
AlGaInN is epitaxially grown on a substrate formed of sapphire, SiC or Si by metal organic chemical vapor deposition (MOCVD)
Implementation Method 3
controlled Fe addition to the resistance layer to diffuse Fe into the buffer layer
Data Source
AI summary
A method of manufacturing a semiconductor element includes a first step of epitaxially growing an AlN layer on a substrate, a second step of forming a buffer layer on the AlN layer by epitaxially growing AlxGayInzN where x, y, and z satisfy x+y+z=1 and y is not zero without adding Fe, a third step of forming a resistance layer on the buffer layer by epitaxially growing AlxGayInzN where x, y, and z satisfy x+y+z=1 and y is not zero while adding Fe, a step of epitaxially growing a channel layer on the resistance layer, a step of epitaxially growing an electron supply layer above the channel layer, and a step of forming an electrode above the electron supply layer.