III-N Epitaxy on Rare Earth Oxide Buffer
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Solution Overview
Problem
The challenge in growing III-N materials on semiconductor substrates like silicon or germanium arises from significant crystal lattice mismatch, which existing methods using rare earth oxides fail to adequately address, as they still result in substantial strain due to incomplete lattice matching.
Innovation Solution
The method involves epitaxially growing a single crystal III-N material on a substrate with a layer of rare earth oxide, elevating the temperature to 750° C. to 1250° C. in the presence of nitrogen or III-containing species, causing a portion of the rare earth oxide to transform into a new alloy, such as rare earth nitride or silicide, thereby reducing lattice mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If layers of rare earth oxides are grown between the substrate and the III-N material, then the crystal lattice mismatch is partially reduced, but substantial strain remains due to incomplete lattice matching
Solution Approach 1:
The patent transforms the rare earth oxide layer into a rare earth nitride layer through chemical composition change. This parameter change (from oxide to nitride) fundamentally alters the lattice constant, enabling much better lattice matching with the III-N material layer. The transformation is achieved through in-situ nitridation during the epitaxial growth process, converting the interface structure to reduce strain.
Solution Approach 2:
The patent creates a composite interface structure consisting of rare earth oxide and rare earth nitride phases. The rare earth nitride forms at the interface with the III-N material, while the rare earth oxide remains in other regions. This composite structure optimizes lattice matching at the critical interface while maintaining the benefits of the rare earth oxide buffer layer.
2Manufacturing precision
If the temperature is elevated to 750°C to 1250°C during epitaxial growth, then the rare earth oxide transforms to a new alloy reducing lattice mismatch, but the process complexity increases
Solution Approach 1:
The patent combines the buffer layer formation and the interface transformation into a single integrated process step. The rare earth oxide layer is deposited, and then immediately transformed into rare earth nitride through in-situ nitridation during the subsequent III-N material epitaxial growth. This merging eliminates separate transformation steps and reduces overall process complexity despite the high temperature requirement.
Solution Approach 2:
The rare earth oxide layer is prepared in advance as a buffer layer before the epitaxial growth begins. This preliminary action sets up the interface structure that will be transformed during growth. By having the oxide layer pre-formed and positioned, the subsequent nitridation transformation occurs in-situ without requiring separate deposition or transformation steps.
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 effectively reduces lattice mismatch between the III-N material and the semiconductor substrate, achieving a closer lattice match and enabling the growth of high-quality single crystal III-N materials with minimal strain, as demonstrated by X-ray data showing lattice parameters within 0.5% of literature values.
Implementation Method 1
a portion of the layer of rare earth oxide is transformed to a new alloy
Implementation Method 2
epitaxially growing a single crystal III-N material on the substrate
Implementation Method 3
in the presence of one of a nitrogen containing species or a III-material species, whereby a portion of the layer of rare earth oxide is transformed to a new alloy
Data Source
AI summary
A method of growing single crystal III-N material on a semiconductor substrate includes providing a substrate including one of crystalline silicon or germanium and a layer of rare earth oxide. A layer of single crystal III-N material is epitaxially grown on the substrate using a process that elevates the temperature of the layer of rare earth oxide into a range of approximately 750° C. to approximately 1250° C. in the presence of an N or a III containing species, whereby a portion of the layer of rare earth oxide is transformed to a new alloy.