Group III Nitride Crystal Doping for Conductivity and Translucency
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Solution Overview
Problem
Existing methods for manufacturing group III nitride crystals, such as HVPE, ammonothermal, and OVPE, face challenges in achieving both high conductivity and low absorption coefficients when N-type dopants are added, leading to difficulties in processing these crystals due to increased absorption coefficients, which hinder the production of high-quality substrates for high-frequency or high-power electronic devices.
Innovation Solution
Doping the group III nitride crystals with an N-type dopant at a concentration of 1×10^19 cm^-3 or more and a germanium element at a concentration nine times higher than the N-type dopant, which reduces the absorption coefficient to 60 cm^-1 or less, thereby enhancing conductivity and preventing crystal coloring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If N-type dopant concentration is increased to improve conductivity, then electrical conductivity is improved, but absorption coefficient increases and crystal is colored
Solution Approach 1:
The patent changes the concentration parameters of dopants by specifying precise ranges: N-type dopant concentration of 1×10^19 to 1×10^21 atoms/cm³ and germanium element concentration of 1×10^20 to 1×10^22 atoms/cm³. This parameter optimization resolves the contradiction by finding the optimal balance point where conductivity is sufficiently improved while absorption coefficient remains controlled at 60 cm⁻¹ or less.
Solution Approach 2:
The patent creates a composite doped structure by combining multiple dopant elements (N-type dopant and germanium element) in specific concentration ratios. This composite doping approach allows the crystal to simultaneously achieve high conductivity from the N-type dopant and low absorption coefficient through the germanium element's compensating effect, resolving the harmful trade-off between these two properties.
2Reliability
If N-type dopant is added to increase conductivity, then electrical conductivity is improved, but crystal coloring occurs
Solution Approach 1:
The patent optimizes the concentration parameter of the N-type dopant to a specific range (1×10^19 to 1×10^21 atoms/cm³) rather than using high concentrations that cause severe coloring. This parameter control prevents the crystal from entering the coloring regime while still achieving the desired conductivity improvement.
Solution Approach 2:
By combining N-type dopant with germanium element in specific concentration ratios, the patent creates a composite doped crystal that maintains optical transparency. The germanium element acts as an optical stabilizer that prevents the coloring effect that would otherwise occur with N-type dopant addition, while the N-type dopant provides the necessary conductivity enhancement.
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 allows for the production of group III nitride crystals with excellent conductivity and low absorption coefficients, facilitating efficient processing and reducing material loss during substrate manufacturing, particularly suitable for high-frequency or high-power electronic devices.
Implementation Method 1
generating and growing a group III nitride crystal on a seed substrate by reacting the introduced group III element-containing gas, the nitrogen atom-containing gas, the N-type dopant-containing gas, and the germanium element-containing gas
Implementation Method 2
the group III nitride crystal is doped with an N-type dopant and a germanium element
Data Source
AI summary
A group III nitride crystal, wherein the group III nitride crystal is doped with an N-type dopant and a germanium element, the concentration of the N-type dopant is 1×1019 cm−3 or more, and the concentration of the germanium element is nine times or more higher than the concentration of the N-type dopant.