Diamond Monocrystal Growth via Lateral Epitaxy and Defect Masking
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Solution Overview
Problem
Current methods for producing single crystals by chemical vapor deposition (CVD) face challenges in achieving high crystalline quality and purity due to the propagation of core dislocations from substrates, and existing techniques for reducing dislocations either compromise purity or require expensive, high-quality substrates.
Innovation Solution
A process involving alternating surface depressions and elevations on the substrate, where lateral homoepitaxial growth is used to block dislocation propagation, combined with etching and mask formation to systematically treat the surface, allowing for repeated growth cycles to achieve low dislocation densities without expensive substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If CVD techniques are used to produce single crystals, then purity control is improved, but core dislocation density increases due to substrate propagation
Solution Approach 1:
The substrate surface is segmented into multiple regions with alternating elevations and hollows, creating spatial separation between defect zones and growth zones. This segmentation prevents dislocation propagation from affecting the entire crystal, allowing high-purity regions to form in the elevations while hollows contain defects.
Solution Approach 2:
Different regions of the substrate are given different functions: elevations serve as growth zones for high-quality crystal formation, while hollows serve as defect traps. This local differentiation allows the system to simultaneously achieve high purity in growth regions and dislocation containment in defect regions.
2Reliability
If HPHT techniques are used to produce single diamond crystals, then core dislocation density is reduced, but purity control deteriorates due to liquid metal bath environment
Solution Approach 1:
A patterned mask structure serves as an intermediary between the HPHT growth environment and the crystal substrate. The mask with its elevation-hollow pattern acts as a spatial filter that allows beneficial dislocation reduction while blocking harmful impurity incorporation from the liquid metal bath, enabling simultaneous achievement of both low dislocation density and high purity.
3Reliability
If expensive high-quality substrates are used, then core dislocation density is reduced, but manufacturing cost increases
Solution Approach 1:
The invention uses relatively inexpensive substrates that can be deliberately patterned with elevations and hollows. These substrates serve as disposable templates that guide crystal growth and trap defects, eliminating the need for expensive pre-screened high-quality substrates while achieving the same dislocation reduction effect.
Solution Approach 2:
The substrate surface is preliminarily patterned with elevations and hollows before crystal growth begins. This preliminary structuring creates a template that guides subsequent crystal growth to occur preferentially in elevation regions, preventing dislocation propagation before it can affect the growing crystal, thereby reducing the need for expensive substrate selection.
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 method effectively reduces dislocation densities to very low levels, enabling the production of high-quality single crystals that can be used as seeds for further growth, thereby improving the crystalline quality and purity of the material.
Implementation Method 1
form a single crystal layer by lateral homoepitaxial growth between the elevations
Implementation Method 2
etching the single crystal layer, deposition of metallic nanoparticles in the defect zones of the single crystal surface
Data Source
Figure 1
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AI summary
The invention relates to a method for forming a monocrystal of material from a monocrystalline substrate having a surface with alternating recesses and elevations, comprising steps of: a) forming a layer of monocrystal by lateral epitaxial growth between the elevations; b) detecting defect areas in the layer of monocrystal by light etching of the layer of monocrystal; c) forming a mask on the layer of monocrystal between the detected defect areas; d) etching the layer of monocrystal provided with the mask, so as to form recesses in the defect areas of the layer and elevations outside the defect areas of the layer; and e) repeating step a).