GaN Substrate Co-Doping for Low-Inclusion 3D Epitaxial Growth
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Solution Overview
Problem
Current methods for fabricating semiconductor substrates based on group 13 nitride materials, such as gallium nitride (GaN), face challenges in achieving homogeneous crystal quality, low surface density of macro-inclusions, and improved electronic properties, particularly under three-dimensional growth conditions, which affect the performance of optoelectronic and electronic devices.
Innovation Solution
A process involving three-dimensional epitaxial growth using metalorganic vapor phase epitaxy (MOVPE) with a dopant gas containing oxygen and germanium or silicon, controlled to achieve specific concentration ratios and growth conditions that reduce macro-inclusions and enhance crystal quality, resulting in wafers with improved electrical and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three-dimensional lateral growth process is used, then dislocation density is reduced to less than 10^7/cm^2, but macro-inclusions with size greater than 10 μm are formed and doping heterogeneity occurs
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration ratios of dopants (N-O: 1×10^17 to 1×10^18/cm³, N-Ge: 1×10^17 to 1×10^18/cm³, N-Si: 1×10^17 to 1×10^18/cm³) during three-dimensional lateral growth. This controlled doping approach maintains low dislocation density while preventing macro-inclusion formation and ensuring homogeneous electrical and optical properties throughout the GaN crystal structure.
2Productivity
If higher growth rate is used (greater than 450 μm/h), then productivity is improved, but surface density of macro-inclusions increases and crystal quality decreases
Solution Approach 1:
The patent optimizes growth parameters by maintaining a controlled growth rate regime and precisely adjusting dopant concentrations (O, Ge, Si) to achieve homogeneous distribution. This parameter optimization allows achieving both high productivity and excellent crystal quality with low macro-inclusion density, resolving the trade-off between growth speed and material quality.
3Device complexity
If conventional single dopant approach is used, then process simplicity is maintained, but doping heterogeneity and non-uniform electrical properties occur in different facet areas
Solution Approach 1:
The patent employs a composite doping strategy by simultaneously introducing three different dopants (Oxygen, Germanium, and Silicon) in specific concentration ranges. This composite approach creates a balanced doping profile that ensures homogeneous electrical and optical properties across all facet areas (basal and non-basal), overcoming the limitations of single-dopant methods while maintaining process feasibility.
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 process yields GaN wafers with reduced macro-inclusion density, enhanced crystal quality, and improved electrical resistivity, enabling better performance in optoelectronic and electronic components like LEDs and power electronics.
Implementation Method 1
deposition of at least one single-crystal layer by three-dimensional epitaxial growth on a starting substrate
Implementation Method 2
Current processes for fabricating a semiconductor material substrate based on nitrides of elements of column 13 or IIIA rest on vapor deposition techniques
Implementation Method 3
supply of an n-dopant gas comprising a first chemical element selected from the chemical elements of group 16 of the periodic table, and at least one second chemical element selected from the chemical elements of group 14 of the periodic table
Data Source
AI summary
A process for fabricating a single-crystal semiconductor material of group 13 nitride, in particular GaN, including the steps of:deposition of at least one single-crystal layer by three-dimensional epitaxial growth on a starting substrate, the layer including areas resulting from the growth of basal facets, and areas resulting from the growth of facets of different orientations, called non-basal facets;supply of an n-dopant gas including a first chemical element selected from the chemical elements of group 16 of the periodic table, and at least one second chemical element selected from the chemical elements of group 14 of the periodic table, such that the concentration of the second element in the areas resulting from the growth of the basal facets is higher than 1.0×1017/cm3, and the concentration of the first element in the areas resulting from the growth of the non-basal facets is lower than 2.0×1018/cm3.