Shallow Colour Centres in Diamond via Cryogenic Ion Implantation

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Solution Overview

Problem

Existing methods for creating shallow color centers in diamond substrates often result in defects near the surface, affecting the spin properties and coherence times, making it challenging to achieve high-quality color centers close to the surface for quantum applications.

Innovation Solution

The use of the channelling effect during ion implantation, combined with precise control of the miscut angle and subsequent annealing and inductively coupled plasma etching, allows for the creation of shallow, negatively charged color centers at a depth of less than 3 nm from the surface, minimizing surface defects and maintaining the crystal structure's integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional ion implantation methods are used to create shallow color centers, then color centers can be formed near the surface, but surface defects are generated that negatively impact spin properties

Engineering Contradiction:
Improvedepth control of color centersVSAvoidsurface defects affecting spin properties
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The invention changes the ion implantation energy parameter to a specific range (50-500 eV) and controls the implantation temperature at cryogenic conditions (4K), which fundamentally alters the interaction mechanism between ions and the diamond lattice, enabling shallow implantation without surface damage

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces conventional high-energy ion implantation mechanisms with a low-energy mechanism that relies on ion diffusion rather than ballistic penetration, substituting the mechanical impact process with a thermal diffusion process that occurs at cryogenic temperatures

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If ion implantation is performed at low energies to create shallow color centers, then color centers are formed near the surface, but additional defects are created during the process

Engineering Contradiction:
Improvedepth of color centers from surfaceVSAvoidquality of color centers
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention performs preliminary cooling of the diamond substrate to cryogenic temperatures (4K) before ion implantation, which prevents defect formation during the implantation process by reducing atomic mobility and preventing displacement cascades

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention introduces a two-step process where ions are first implanted at low energy into a cryogenically cooled substrate, then the substrate is annealed to allow defect annealing and color center formation, using the temperature cycle as an intermediary mechanism

Inventive Principle:
Principle #24Intermediary (Mediator)

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 color centers with improved signal strength, coherence times, and uniform properties, enhancing their suitability for quantum sensing and computing applications by ensuring a high percentage of centers are located close to the surface with minimal damage to the crystal lattice.

Implementation Method 1

a diamond substrate comprising shallow colour centres implanted by utilizing a channelling effect is characterized in that the colour centres comprise negatively charged colour centres at a depth of less than 3 nm from the surface of the diamond substrate

Methodology Applied
Scientific EffectChannelling effect:

Data Source

PatentEP4428274A1Shallow colour centres in diamond for application in quantum technology
Publication Date: 2024.09.11 UNIV ULM
  • EP4428274A1 patent drawingFigure 1a~1b
  • EP4428274A1 patent drawingFigure 2~3
  • EP4428274A1 patent drawingFigure 4a~4b

AI summary

This invention relates to a diamond substrate comprising shallow colour centres and to a method for the creation of shallow colour centres in a diamond substrate.