Si-Doped GaN Substrate for Uniform Conductivity and Low Defects
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Solution Overview
Problem
Existing GaN substrates face issues with cissing and non-uniform doping, leading to increased resistance and reduced device yield when high Si concentrations are used, which hinders the production of conductive GaN substrates for laser diodes and vertical GaN power devices.
Innovation Solution
The development of a GaN substrate with a Si-doped layer that incorporates Si atoms efficiently by narrowing the terrace width during epitaxial growth and controlling the distance between the ejection nozzle and the substrate surface, ensuring uniform doping and reducing recessed defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Si doping concentration is increased to reduce resistance, then electrical conductivity is improved, but cissing occurs and device yield deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Si doping concentration within a specific range (1×10^18 to 1×10^19 atoms/cm³) and adjusting the terrace width during epitaxial growth. By optimizing these parameters, the patent achieves low resistance while preventing cissing, thus resolving the contradiction between electrical conductivity and device yield.
2Reliability
If Si doping concentration is increased to reduce resistance, then electrical conductivity is improved, but Si distribution becomes non-uniform and activation rate decreases
Solution Approach 1:
The patent controls the Si doping concentration within a specific range and adjusts the terrace width to ensure uniform Si distribution. By optimizing these parameters, the patent maintains high activation rate and uniform doping throughout the substrate, resolving the contradiction between electrical conductivity and manufacturing precision.
Solution Approach 2:
The patent introduces terrace width as an additional control dimension during epitaxial growth. By controlling the terrace width in the spatial dimension, the patent achieves uniform Si distribution across the substrate surface, preventing non-uniform doping even at high Si concentrations.
3Reliability
If Si doping concentration is increased to reduce resistance, then electrical conductivity is improved, but resistance at end portions increases
Solution Approach 1:
The patent optimizes the Si doping concentration and terrace width parameters to ensure uniform resistance characteristics across the entire substrate, including end portions. By controlling these parameters within specific ranges, the patent achieves consistent electrical conductivity throughout the substrate, resolving the contradiction between overall conductivity and resistance uniformity.
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 achieves resistance reduction and improves device yield by preventing cissing and ensuring uniform Si distribution, making the substrate suitable for laser diodes and vertical GaN power devices.
Implementation Method 1
a Si-doped GaN layer on at least a surface of the main surface 1, in which the Si-doped GaN layer has a Si concentration of 1×10^18 atoms/cm³ or more
Data Source
AI summary
A GaN substrate includes a main surface 1 inclined by 0° to 10° from a (0001) crystal plane which is a Ga-polar plane, and including a Si-doped GaN layer on at least a surface of the main surface 1, in which the Si-doped GaN layer has a Si concentration of 1×1018 atoms/cm3 or more, and a total of bottom areas of recessed defects on a surface of the Si-doped GaN layer is 15% or less of an area of the entire surface of the Si-doped GaN layer.