Direct Laser Writing of Nucleation Sites for Patterned Diamond Growth

At a Glance

Metadata	Details
Publication Date	2025-03-11
Journal	Journal of Electronic Materials
Authors	Sumeer Khanna, J. Narayan, Roger J. Narayan
Citations	1
Analysis	Full AI Review Included

Technical Documentation & Analysis: Direct Laser Writing of Nucleation Sites for Patterned Diamond Growth

Executive Summary

This research demonstrates a novel, scalable method for fabricating patterned diamond structures by combining Direct Laser Writing (DLW) lithography with Hot-Filament Chemical Vapor Deposition (HFCVD). This process sequence is highly relevant for engineers developing next-generation quantum and high-power electronic devices.

Patterned Nucleation: 3D polymer structures fabricated via two-photon polymerization (2PP) were thermally carbonized (pyrolyzed at 540°C) to create highly selective, patterned nucleation sites on Si (100) and Sapphire (0001) substrates.
High sp³ Content: The resulting carbonized structures exhibited a high sp³ content (45-55%), providing effective starting points for diamond growth.
High-Quality Diamond: The grown diamond crystallites showed exceptional quality, confirmed by a sharp Raman peak (1333-1335 cm⁻¹) with an ultra-low Full Width at Half Maximum (FWHM) of ≤ 5 cm⁻¹.
Rapid, Controlled Growth: Diamond crystallites grew rapidly (~0.7 µm/h) in the preferred <100> direction, displaying clear fourfold faceting and micrometer-scale uniformity (1-2 µm).
Advanced Nucleation Potential: Pulsed Laser Annealing (PLA) was successfully used to convert the carbonized layer into the Q-carbon phase, achieving 70-80% sp³ content, which offers superior, barrier-less nucleation sites for future high-density, uniform diamond films.
Application Relevance: The patterned diamond arrays are directly applicable to quantum computing (NV centers via nitrogen doping), superconducting devices, and high-power electronics.

Technical Specifications

The following hard data points were extracted from the experimental results and methodologies:

Parameter	Value	Unit	Context
Carbonization Temperature	540	°C	Thermal annealing in inert atmosphere
Substrate Temperature (HFCVD)	~700	°C	During diamond deposition
Filament Temperature (HFCVD)	~2000	°C	Tungsten (W) filaments
HFCVD Gas Pressure (H₂)	100	T	Hydrogen flow
HFCVD Gas Pressure (CH₄)	2	T	Methane flow
Carbonized sp³ Content	45-55	%	Measured via Raman/XPS after pyrolysis
Q-Carbon sp³ Content (PLA)	70-80	%	After Pulsed Laser Annealing
Diamond Raman Peak Shift	1333-1335	cm⁻¹	High-quality diamond signature
Diamond FWHM	≤ 5	cm⁻¹	Full Width at Half Maximum (indicates low defect density)
Diamond Crystallite Size	1-2	µm	Micrometer scale
Diamond Growth Rate	~0.7	µm/h	Rapid growth, no incubation time observed
Calculated Residual Stress (Max)	2.85	GPa	Based on 1335 cm⁻¹ Raman shift
DLW Laser Wavelength	780	nm	Two-Photon Polymerization (2PP)
DLW Pulse Duration	80-100	fs	Femtosecond laser pulses

Key Methodologies

The patterned diamond growth was achieved through a precise, multi-step sequence:

CAD Modeling: 3D structures (e.g., triangular rods, blocks) were designed using SolidWorks, defining the final 2D pattern array for selective nucleation.
3D Printing (DLW-2PP): Structures were fabricated on Si (100) and Sapphire (0001) substrates using a Nanoscribe PPGT2 platform based on two-photon absorption (2PA).
- Laser parameters included 780 nm wavelength, 80-100 fs pulse duration, and 50 mW average power.
Thermal Annealing (Carbonization): The polymer structures were pyrolyzed in ambient air via a two-step thermal cycle:
- Stabilization: Ramp to 420°C, held for 15 minutes.
- Carbonization: Ramp to 540°C, held for 15 minutes. This process resulted in volume reduction and the formation of glassy carbon structures (45-55% sp³).
Optional Q-Carbon Conversion: In advanced experiments, Pulsed Laser Annealing (PLA) was applied (~0.7 J/cm²) to convert the carbonized layer into the Q-carbon phase with embedded nanodiamonds (ND), significantly increasing the sp³ content (70-80%) for enhanced nucleation density.
Diamond Growth (HFCVD): Diamond was deposited using Hot-Filament CVD with Tungsten filaments (~2000°C).
- Process gases were Methane (CH₄) and Hydrogen (H₂).
- Deposition occurred at a substrate temperature of ~700°C for approximately 3 hours, resulting in continuous, faceted diamond crystallites.

6CCVD Solutions & Capabilities

The research successfully demonstrates the potential for highly controlled, patterned diamond growth, a critical requirement for advanced micro- and nano-electronic devices. 6CCVD, as an expert supplier of MPCVD diamond, offers the materials and customization capabilities necessary to replicate, scale, and extend this research into commercial applications.

Applicable Materials for Replication and Extension

Application Requirement (from Paper)	6CCVD Material Solution	Technical Rationale
High-Quality Patterned Growth	Optical Grade Single Crystal Diamond (SCD)	SCD offers the lowest defect density (Ra < 1nm polished), providing the ideal template for high-fidelity epitaxial growth (Domain-Matching Epitaxy, DME) referenced in the paper.
Superconducting/Electronic Devices	Heavy Boron-Doped Diamond (BDD)	BDD is essential for replicating the Q-carbon/Q1/Q2/Q3 phases mentioned, which exhibit distinct superconducting transition temperatures (up to 110 K).
Quantum Sensing (NV Centers)	High-Purity SCD (Nitrogen Doped)	6CCVD can supply SCD wafers with controlled nitrogen doping during growth, enabling the fabrication of high-coherence Nitrogen Vacancy (NV) centers directly within the patterned structures.
Large-Area Selective Coatings	Polycrystalline Diamond (PCD) Wafers	For scaling the patterned growth to industrial dimensions, 6CCVD offers PCD plates/wafers up to 125mm in diameter, far exceeding typical lab-scale substrates.

Customization Potential for Device Integration

The DLW technique allows for complex 3D patterning, which requires equally precise material preparation and post-processing. 6CCVD provides comprehensive services to meet these advanced requirements:

Custom Dimensions and Substrates: While the paper used Si and Sapphire, 6CCVD can provide SCD and PCD plates in custom dimensions and thicknesses (SCD/PCD: 0.1 µm to 500 µm; Substrates: up to 10 mm thick) suitable for integration with existing microfabrication lines.
Ultra-Low Roughness Polishing: Achieving the high-quality interface necessary for potential epitaxial growth (DME) requires exceptional surface preparation. 6CCVD guarantees ultra-smooth polishing:
- SCD: Surface roughness (Ra) < 1 nm.
- Inch-size PCD: Surface roughness (Ra) < 5 nm.
Integrated Metalization Services: For creating functional devices (e.g., electrodes, contacts) on the patterned diamond, 6CCVD offers in-house metalization capabilities, including deposition of Au, Pt, Pd, Ti, W, and Cu layers, eliminating the need for external processing steps.
Precision Laser Cutting: 6CCVD can perform precision laser cutting and shaping of diamond wafers to match the specific geometric requirements of the patterned arrays.

Engineering Support

The successful transition from HFCVD (Hot-Filament) to scalable MPCVD (Microwave Plasma) requires specialized knowledge. 6CCVD’s in-house PhD engineering team specializes in optimizing MPCVD recipes for specific applications, including:

Nucleation Optimization: Assisting researchers in translating the Q-carbon/PLA nucleation enhancement technique to high-throughput MPCVD systems for highly uniform, high-density diamond films.
Material Selection for Quantum Projects: Providing expert consultation on selecting the optimal SCD grade and controlled doping levels required for similar Nitrogen Vacancy (NV) Center projects.
Global Logistics: Ensuring reliable, global delivery of custom diamond materials (DDU default, DDP available) to support international research collaborations.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Abstract Direct laser writing (3D printing) is rapidly emerging as a versatile method for fabricating novel 3D structures that are needed for quantum computing, superconducting devices, selective coatings, and biomedical sensors. Here, we have created 2D patterns with potential for 3D diamond structures by direct laser writing lithography, which are carbonized in an inert Ar atmosphere at 540°C and then used as nucleation sites for diamond growth via hot-filament chemical vapor deposition (HFCVD). An array of 3D structures was fabricated via a two-photon polymerization process using a photo-polymeric resin on Si (100) and sapphire (0001) substrates. These 3D structures carbonized by thermal annealing show approximately 45-55% sp 3 content, as confirmed by Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) analytical techniques. As per the end application of the device, the computer-aided design (CAD) of the structure can be modified to innovative shapes that can be carbonized to provide selective nucleation sites for placing diamond crystallites at the desired locations, which is an important component for device fabrication. The diamond crystallites show a distinctive Raman peak upshift in the range of 1333-1335 cm −1 with a full width at half maximum of ≤ 5 cm −1 , indicating some strain across the diamond and Si (100) substrate. A fourfold growth morphology with {111} planes of diamond crystallites is shown by high-resolution scanning electron microscopy (HR-SEM), which correlates with the <100> growth of diamond. Additionally, we show the possibility of creating 3D structures in Q-carbon phase with embedded nanodiamond crystallites via pulsed laser annealing (PLA) of carbonized structures. Graphical Abstract

Tech Support

Original Source

DOI: https://doi.org/10.1007/s11664-025-11847-1