Single Crystal Diamond Seed Substrate with Through-Opening
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Solution Overview
Problem
The challenge is to produce single crystal diamond with high crystalline quality and purity by chemical vapor deposition, as existing methods face limitations due to high dislocation densities in diamond synthesized by plasma-enhanced chemical vapor deposition, which hinder its application in high-value fields like optics and electronics, and the use of high-quality HPHT substrates is restricted by their scarcity and cost.
Innovation Solution
A single-crystal diamond seed substrate is shaped with a through-opening to promote lateral growth, inhibiting dislocation propagation and reducing dislocation density, allowing for the growth of large, high-purity diamond crystals using a substrate of moderate quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If diamond is synthesized by plasma-enhanced chemical vapor deposition, then large dimensions and moderate substrate quality are achieved, but dislocation density becomes very high (10^4 to 10^6 cm^-2)
Solution Approach 1:
The substrate surface is segmented into multiple facets (typically 3-8 facets) arranged around a central axis. Each facet acts as an independent growth zone with controlled orientation, allowing dislocations to be confined to specific regions rather than propagating uniformly across the entire crystal. This segmentation enables large-area growth while maintaining high crystalline quality in each facet region.
Solution Approach 2:
Different regions of the substrate are given different crystallographic orientations and growth conditions. The facets are oriented at specific angles (typically 70-80 degrees relative to the substrate normal) to optimize dislocation confinement. The central region near the opening has different properties from the peripheral regions, creating localized quality zones that collectively produce a high-quality large crystal.
2Manufacturing precision
If high-quality HPHT substrates are used, then dislocation density is greatly reduced, but substrate availability becomes extremely limited and cost increases
Solution Approach 1:
The invention uses readily available, relatively inexpensive CVD-grown diamond substrates with moderate initial quality instead of rare, expensive HPHT substrates. The through-opening structure acts as a 'disposal' mechanism for dislocations, allowing the use of lower-quality starting materials while achieving high-quality output. The substrate serves its purpose of initiating growth and then allows dislocations to be eliminated through the opening.
Solution Approach 2:
The invention changes the structural parameters of the substrate by introducing a through-opening and creating faceted surfaces with specific orientations. This transforms a flat, closed substrate into an open, multi-faceted structure that fundamentally alters dislocation propagation behavior. The geometric parameters (facet angles, opening size, number of facets) are optimized to achieve dislocation confinement while maintaining ease of manufacture.
3Speed
If traditional substrate growth methods are used, then growth proceeds vertically, but dislocations propagate along preferred directions perpendicular to the substrate surface
Solution Approach 1:
The invention introduces lateral dimensions to dislocation confinement by creating faceted surfaces that extend sideways from the growth axis. Instead of dislocations propagating only vertically, the faceted geometry redirects dislocation paths into lateral directions where they terminate at the facet surfaces or are confined to specific zones. This dimensional redirection maintains vertical growth speed while eliminating vertical dislocation propagation.
Solution Approach 2:
The faceted structure creates nested growth zones where inner facets are surrounded by outer facets. Dislocations generated in inner regions are confined by the geometry of surrounding facets, creating a protective nested structure. The through-opening at the center allows dislocations from all facets to eventually terminate, creating a nested confinement system that maintains high growth rates while reducing dislocation density.
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 density in the grown diamond crystals, enabling the production of large, high-quality diamond monocrystals with low dislocation concentrations, suitable for advanced applications without the need for expensive, high-quality substrates.
Implementation Method 1
homoepitaxial growth of diamond by chemical vapor deposition
Data Source
Figure 1~3
Figure 4~6d
Figure 5a~5c
AI summary
The invention concerns a single crystal diamond seed substrate, for homoepitaxial diamond growth by chemical vapour deposition, having a body consisting of: - a bottom wall acting as a support on the base or substrate holder of a reactor, and - one or more outer side walls, and one or more outer top walls on which the homoepitaxial growth takes place, characterised in that the inside of the body is perforated by a through-opening extending between the top wall or walls and the bottom wall, thus delimiting one or more inner walls on which the homoepitaxial growth also takes place, the through-opening having a width of at least 0.5 mm.