Laser-induced luminescence of boron-doped synthetic diamond at various laser pulse durations
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2022-01-01 |
| Journal | Оптика и спектроскопия |
| Authors | E. A. Oleynichuk, П. А. Данилов, V. N. Lednev, P. A. Sdvizhenskii, М. С. Кузнецов |
| Institutions | Prokhorov General Physics Institute, All-Russian Research Institute for Optical and Physical Measurements |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This study investigates the laser-induced broadband luminescence (A-band) in Type IIb boron-doped synthetic diamond (BDD) using ultrashort laser pulses, establishing key relationships between pulse duration, intensity, and emission mechanisms.
- Material and Excitation: HPHT synthetic Type IIb BDD (boron concentration ~1017 cm-3) was excited using 515 nm ultrashort pulses with durations varying from 0.3 ps to 6.2 ps.
- Broadband Emission: A characteristic A-band luminescence, attributed to radiative recombination at dislocations and point imperfections, was observed across the 350-650 nm range.
- Pulse Duration Effect: Increasing the laser pulse duration (at similar pulse energy) caused a measurable shift of the luminescence maximum toward the low-energy (longer wavelength) region.
- Nonlinear Excitation Confirmed: The luminescence yield of the blue peak (~434 nm) exhibited a nonlinear dependence on incident laser intensity (slope coefficient 1.2 ± 0.1 to 1.4 ± 0.1), confirming efficient two-photon excitation mechanisms.
- Linear Excitation: Conversely, the red shoulder peak (~537 nm) showed a linear dependence on intensity (slope coefficient ~1.0 ± 0.1), suggesting dominance by single-photon processes.
- Engineering Relevance: The findings provide critical data for controlling defect-related luminescence in BDD, essential for developing diamond-based optoelectronic devices and high-power laser components.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Diamond Type | IIb (HPHT) | N/A | Boron-doped synthetic diamond |
| Sample Thickness | ~300 | µm | Thin wafer geometry |
| Crystal Orientation | (001) | N/A | Wafer surface orientation |
| Boron Concentration ({100} sector) | ~1017 | cm-3 | Estimated from 2800 cm-1 absorption band |
| Excitation Wavelength (PL) | 515 | nm | Second harmonic of Yb fiber laser |
| Pulse Durations Tested | 0.3, 1.3, 6.2 | ps | Variable ultrashort pulse regime |
| Maximum Pulse Energy (Emax) | 3.3 | µJ | Used for excitation |
| Pulse Repetition Rate | 100 | kHz | Constant rate |
| Raman Shift (Optical Phonon) | 1331 | cm-1 | Corresponds to 572 nm peak at 532 nm pump |
| A-Band Luminescence Range | 350-650 | nm | Broadband emission range |
| Blue Peak Wavelength | ~434 | nm | Exhibits nonlinear intensity dependence |
| Red Peak Wavelength | ~537 | nm | Exhibits linear intensity dependence |
| Intensity Slope (434 nm peak) | 1.2 ± 0.1 to 1.4 ± 0.1 | N/A | Nonlinear (Two-photon) excitation |
| Intensity Slope (537 nm peak) | 1.0 ± 0.1 to 1.1 ± 0.1 | N/A | Linear (Single-photon) excitation |
Key Methodologies
Section titled “Key Methodologies”The experiment utilized a combination of spectroscopic and ultrashort laser techniques to characterize the BDD sample and measure its photoluminescence (PL) response.
- Material Selection and Preparation: A synthetic HPHT Type IIb boron-doped diamond wafer (4x4 mm, ~300 µm thick) was selected. The central {100} growth sector, containing fewer imperfections, was chosen for PL measurements.
- Initial Characterization (IR and Raman):
- Transmission spectra (2-25 µm) were measured using a Bruker Vertex 70v IR Fourier-spectrometer to confirm the IIb type and estimate boron concentration (approx. 1017 cm-3).
- Confocal Raman spectroscopy (Confotec MR350, 532 nm pump) was used to confirm the diamond lattice structure (Raman line at 1331 cm-1).
- Ultrashort Pulse Excitation: The second harmonic radiation (515 nm) of a Satsuma fiber ytterbium laser was used as the pump source. Pulse durations were varied (0.3, 1.3, and 6.2 ps) at a constant 100 kHz repetition rate.
- Focusing and Geometry: The 515 nm laser beam was focused approximately 150 µm beneath the surface using a microscope objective (NA = 0.25).
- Luminescence Collection and Detection:
- PL was collected orthogonally to the pump beam using a LOMO UV objective lens (NA = 0.2).
- The resulting spectra were analyzed using an Andor Shamrock 303i ICCD-spectrometer across the 300-800 nm range.
- The intense region around the pump wavelength (460-530 nm) was intentionally excluded to prevent detector damage.
- Intensity Dependence Analysis: The maximum PL amplitude for the 434 nm and 537 nm peaks was plotted against the incident laser intensity on a double logarithmic scale to determine the slope coefficients, revealing the order of the excitation process (linear vs. nonlinear).
Commercial Applications
Section titled “Commercial Applications”The research on laser-induced luminescence and nonlinear excitation in boron-doped diamond (BDD) supports several high-value commercial and scientific applications:
- Optoelectronic Devices: BDD is a p-type semiconductor with a large band gap. This work aids in developing high-efficiency UV and visible light emitters, detectors, and integrated photonic circuits based on controlled defect centers.
- High-Power Laser Optics: Understanding the nonlinear (two-photon) absorption mechanisms is crucial for designing diamond windows, lenses, and optical components that must survive extreme power densities from femtosecond and picosecond lasers without catastrophic failure.
- Extreme Environment Electronics: Due to its high thermal conductivity and radiation hardness, BDD is utilized for robust electronics and sensors in demanding environments, including:
- Deep space and near-Earth satellite research.
- Nuclear power plant monitoring and control systems.
- Quantum Sensing and Computing Platforms: The A-band luminescence is associated with dislocations and point imperfections. Controlling the formation and excitation of these defects is a prerequisite for engineering specific, stable color centers (like NV or SiV) required for quantum memory and sensing applications.
- Advanced Electrochemistry: BDD electrodes are highly valued for their chemical inertness and wide potential window, used in industrial processes such as wastewater treatment, ozone generation, and specialized chemical synthesis.
View Original Abstract
Excitation of type IIb synthetic diamond by ultrashort laser pulses in the visible range causes broadband luminescence in the UV visible range; the observed luminescence band can be attributed to the A band characteristic of diamonds. The photoluminescence spectra were obtained at different laser pulse durations (0.3-6.2 ps) depending on the pulse energy. A nonlinear dependence of the luminescence yield on the intensity of ultrashort pulses is established. Keywords: broadband luminescence, boron doped diamond, two-photon luminescence, A-band.