Photoluminescence from voids created by femtosecond-laser pulses inside cubic-BN
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2015-12-03 |
| Journal | Optics Letters |
| Authors | R. Buividas, I. Aharonovich, G. Seniutinas, X. W. Wang, L. Rapp |
| Institutions | University of Technology Sydney, Swinburne University of Technology |
| Citations | 30 |
| Analysis | Full AI Review Included |
MPCVD Diamond for Deterministic Color Center Engineering: Analysis of fs-Laser Void Formation in Wide Bandgap Materials
Section titled “MPCVD Diamond for Deterministic Color Center Engineering: Analysis of fs-Laser Void Formation in Wide Bandgap Materials”This technical documentation analyzes the findings of “Photoluminescence from voids created by femtosecond laser pulses inside cubic-BN” and identifies how 6CCVD’s expertise in MPCVD diamond growth and fabrication directly supports the replication and extension of this advanced defect engineering research into the diamond photonics platform.
Executive Summary
Section titled “Executive Summary”- Core Achievement: Demonstrated deterministic fabrication of optically stable, room-temperature color centers (RC1, RC2, RC3 defects) in cubic Boron Nitride (c-BN) using ultra-short (fs) laser-induced void formation.
- Methodology: Utilized high numerical aperture (NA = 1.42) focusing of 230 fs laser pulses (515 nm or 1030 nm) deep beneath the c-BN surface to create sub-wavelength voids (50-200 nm).
- Photonic Relevance: The defects, linked to N-vacancy formation (Frenkel pairs), exhibit bright Photoluminescence (PL) in the red spectral range (e.g., RC3 ZPL at 628 nm) with a typical excited state lifetime of ~4 ns.
- Material Analogy: The study highlights c-BN’s strong structural and electronic analogy to diamond, confirming that similar defect formation mechanisms are viable via laser patterning, establishing a critical pathway for the deterministic engineering of NV-centers and other point defects in Single Crystal Diamond (SCD).
- 6CCVD Value Proposition: 6CCVD provides the necessary Electronic/Optical Grade SCD substrates, high-precision polishing (Ra < 1 nm), and custom geometry services required to facilitate high-NA, sub-surface fs-laser microfabrication for advanced quantum applications.
Technical Specifications
Section titled “Technical Specifications”The table below summarizes the critical experimental parameters and material properties identified in the research, focusing on data points relevant for replicating the process in MPCVD diamond substrates.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Target Material Bandgap | 6.5 | eV | Cubic Boron Nitride (c-BN) |
| Material Refractive Index (n) | ~2.125 | None | Relevant for tight focusing/spherical aberration |
| Laser Pulse Duration (Tp) | 230 | fs | Ultra-short pulse irradiation source |
| Primary Wavelength (λ) | 515 / 1030 | nm | Second Harmonic / Fundamental |
| Focusing Numerical Aperture (NA) | 1.42 | None | Required for sub-wavelength spatial resolution |
| Focus Depth Below Surface | 10 - 20 | µm | Internal material modification regime |
| Void/Structure Diameter | 50 - 200 | nm | Sub-wavelength feature size achieved |
| Void Formation Threshold (515 nm) | 4.5 | nJ | Minimum single pulse energy |
| Identified Defect Emission (RC3 PL) | 628 ± 2 | nm | Photoluminescence Zero Phonon Line (ZPL) |
| PL Excited State Lifetime (τ) | ~4 | ns | Measured at room temperature |
Key Methodologies
Section titled “Key Methodologies”The study utilized femtosecond laser irradiation to deterministically create point defects through internal structural modification, a technique directly applicable to SCD for quantum applications.
- High-Pressure Growth Material: c-BN crystals grown via the belt-type high pressure equipment were used, emphasizing the need for high-quality, wide bandgap material.
- fs-Laser Direct Writing: Ultra-short pulses (Tp = 230 fs) were employed, critical for achieving high peak irradiance (> 10 TW/cm2) necessary for nonlinear absorption and void formation deep within the material bulk.
- Tight Focusing: A high Numerical Aperture objective lens (NA = 1.42) was implemented to achieve diffraction-limited focal size and concentrate energy to create sub-wavelength damage sites (50-200 nm diameter).
- Deterministic Defect Formation: Voids were fabricated in controlled arrays using single-pulse conditions at precise energy levels (Ep typically 9-90 nJ range) to eliminate cross-talk and control defect location.
- Optical Characterization: Confocal microscopy (405 nm excitation) and time-resolved PL measurements (510 nm/100 ps) were used to locate and characterize the created color centers at room temperature.
6CCVD Solutions & Capabilities
Section titled “6CCVD Solutions & Capabilities”This research validates femtosecond laser modification as a powerful tool for deterministic defect placement in wide bandgap materials, a methodology 6CCVD is uniquely positioned to support within the diamond platform (NV centers, SiV centers, etc.).
Applicable Materials
Section titled “Applicable Materials”The precise control over defect placement demonstrated here requires the highest purity material to ensure the quantum properties of the resulting color centers are not compromised by spurious impurities.
- Recommendation: Electronic/Optical Grade Single Crystal Diamond (SCD).
- Specifications:
- Purity: Ultra-low nitrogen content (typically < 5 ppb), critical for maximizing the sensitivity and coherence time of externally introduced color centers (like NV⁻ centers).
- Thickness: Custom wafers available in the range of 0.1 µm to 500 µm, allowing researchers to select the optimal thickness for specific objectives (e.g., thin films for integrated photonics or bulk substrates for deep focusing).
- Crystal Quality: MPCVD SCD exhibits superior lattice quality and homogeneity, minimizing background noise and maximizing the quantum efficiency of deterministically written defects.
Customization Potential
Section titled “Customization Potential”The experimental requirements (tight focusing, sub-surface modification, specific crystal orientation) align perfectly with 6CCVD’s fabrication capabilities.
| Service Category | Requirement from Paper | 6CCVD Capability & Solution |
|---|---|---|
| Surface Finish | Necessary high-NA optical access, minimizing scattering. | Polishing: Ra < 1 nm (SCD). Essential for high-NA objectives (NA=1.42) used for sub-surface writing. |
| Dimensions/Geometry | Use of specific facet planes; arrays fabricated tens of µm below the surface. | Custom Dimensions: Plates/wafers up to 125 mm. Custom Laser Cutting/Shaping: For specialized optical windows, prisms, or micro-optical elements. |
| Metalization | Future integration of color centers into micro-optical circuits. | In-house Metalization: Deposition of single or multilayer stacks including Ti/Pt/Au, W, Cu, Pd. Customized contact fabrication for electrode integration. |
| Growth Parameters | Controlling precursor defects (like N-vacancies in c-BN). | Custom Growth Recipes: Ability to precisely tune gas flow ratios (e.g., N2 or B incorporation) to control background defect concentration in SCD or create heavily Boron-Doped Diamond (BDD). |
Engineering Support
Section titled “Engineering Support”6CCVD’s in-house PhD team can assist with material selection and design for similar quantum and nanophotonic projects. We offer deep expertise in:
- Optimizing nitrogen incorporation within SCD during growth to maximize the yield of NV centers formed by post-processing (e.g., implantation followed by annealing, or laser voiding).
- Providing crystallographically oriented substrates necessary for maximizing PL collection efficiency from specific defect centers.
- Consultation on surface preparation techniques to ensure compatibility with high-energy fs-laser processing and post-processing steps.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Photoluminescence (PL) from femtosecond-laser-modified regions inside cubic-boron nitride (c-BN) was measured under UV and visible light excitation. Bright PL at the red spectral range was observed, with a typical excited state lifetime of ∼4 ns. Sharp emission lines are consistent with PL of intrinsic vibronic defects linked to the nitrogen vacancy formation (via Frenkel pair) observed earlier in high-energy electron-irradiated and ion-implanted c-BN. These, formerly known as the radiation centers, RC1, RC2, and RC3, have been identified at the locus of the voids formed by a single femtosecond-laser pulse. The method is promising to engineer color centers in c-BN for photonic applications.