CVD Diamond Substrate Defect Control via HPHT Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current diamond synthesis techniques face challenges in achieving high crystalline quality with low extended defect density and controlled point defect concentrations, particularly in high pressure-high temperature (HPHT) and chemical vapour deposition (CVD) processes, which affect the growth rate, doping precision, and production of multilayer samples with sharp interfaces.
Innovation Solution
The development of a method to produce single crystal CVD diamond with controlled extended defect density and point defect concentration by using HPHT techniques to create substrates with low extended defect densities, allowing for subsequent CVD growth that minimizes dislocation nucleation and achieves exceptional crystalline quality and precise doping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HPHT synthesis with nitrogen getters is used to reduce nitrogen content, then crystalline quality improves, but growth rate decreases
Solution Approach 1:
The synthesis process is divided into two distinct stages: first HPHT synthesis to create the diamond substrate with controlled nitrogen content, then CVD growth to achieve high crystalline quality. This segmentation allows each process to optimize for its specific function without compromising the other.
Solution Approach 2:
A nitrogen getter is introduced as an intermediary substance in the HPHT synthesis process to selectively remove nitrogen from the system. This mediator enables precise control of nitrogen content without requiring extreme parameter adjustments that would slow growth rate.
2Manufacturing precision
If HPHT techniques are used to grow diamond, then high crystalline quality can be achieved, but controlled doping with point defects becomes difficult
Solution Approach 1:
The invention changes the fundamental parameters of the synthesis process by transitioning from HPHT to CVD conditions. This parameter change enables precise control of point defect concentration through gas phase doping during CVD growth, while maintaining the high crystalline quality established during HPHT substrate formation.
3Quantity of substance
If HPHT synthesis is used to produce diamond, then material can be obtained, but production of multilayer samples with sharp interfaces is difficult
Solution Approach 1:
The diamond structure is segmented into multiple layers through sequential CVD growth on HPHT substrates. Each layer can be independently controlled with sharp interfaces, allowing production of multilayer samples with precise interface definition that cannot be achieved through conventional HPHT synthesis alone.
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 results in CVD diamond with extended defect densities below 400/cm² and controlled point defect densities, addressing limitations in HPHT processes such as growth rate, doping precision, and multilayer sample production, while enabling the creation of high-quality diamond materials for various applications.
Implementation Method 1
The synthesis of diamond by various methods is well known and well established. One such example is the synthesis of diamond under high temperature and high pressure (HPHT).
Implementation Method 2
In the temperature gradient method, the driving force for crystal growth is the supersaturation due to the difference in solubilities of the carbon source material and the growing crystal as a result of a temperature difference between the two. The carbon that is present in the higher temperature region migrates to the seed crystal
Implementation Method 3
The nitrogen getter or agent is added to the solvent/catalyst, which is typically a molten alloy of the transition metals cobalt, iron and nickel. This agent has the effect of preferentially sequestering the nitrogen in the metallic melt, either as a solute or as a precipitated nitride or carbo-nitride.
Implementation Method 4
such material has many potential applications, including use as a substrate in a subsequent chemical vapour deposition (CVD) growth process
Data Source
AI summary
The invention relates to a single crystal CVD diamond material, wherein the extended defect density as characterized by X-ray topography is less than 400/cm2 over an area of greater than 0.014 cm2. The invention further relates to a method for producing a CVD single crystal diamond material according to any preceding claim comprising the step of selecting a substrate on which to grow the CVD single crystal diamond, wherein the substrate has at least one of a density of extended defects as characterized by X-ray topography of less than 400/cm2 over an area greater than 0.014 cm2; an optical isotropy of less than 1×10-5 over a volume greater than 0.1 mm3; and a FWHM X-ray rocking curve width for the (004) reflection of less than 20 arc seconds.