A 3D diamond detector for particle tracking

At a Glance

Metadata	Details
Publication Date	2015-10-07
Journal	Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
Authors	M. Artuso, F. Bachmair, L. Bäni, M. Bartosik, J. B. Beacham
Institutions	Istituto Nazionale di Fisica Nucleare, Syracuse University
Citations	32
Analysis	Full AI Review Included

Technical Documentation & Analysis: 3D Diamond Detectors for Particle Tracking

This document analyzes the research paper “A 3D diamond detector for particle tracking” (Artuso et al., 2016) and outlines how 6CCVD’s advanced MPCVD diamond materials and fabrication services can support the replication, scaling, and optimization of this critical high-energy physics technology.

Executive Summary

The development of 3D diamond detectors using femtosecond laser processing represents a significant advancement for high-radiation environments, such as the High-Luminosity Large Hadron Collider (HL-LHC).

Decoupled Geometry: The 3D electrode structure successfully decouples the charge collection distance (CCD) from the sensor thickness, a critical limitation in traditional planar detectors.
Low Voltage Operation: Full charge collection was achieved in the 3D detector at an ultra-low bias voltage of 25 V, compared to the > 450 V required by the planar strip detector fabricated on the same material.
Material Efficiency: This low-voltage operation allows for the effective use of diamond materials with lower intrinsic CCD, potentially reducing material costs for large-scale tracking arrays.
Fabrication Method: Conductive channels were created by inducing a phase change (graphitization) within the electronic grade Single Crystal CVD (scCVD) diamond bulk using a femtosecond laser.
Performance Equivalence: The 3D detector (13,900 e) achieved a Most Probable Charge (MPC) signal equivalent to the high-voltage planar detector (13,800 e).
Optimization Required: Raman spectroscopy on Polycrystalline CVD (pCVD) samples identified systematic differences in channel quality between the laser entry (“seed”) and exit sides, indicating a need for precise material and laser parameter optimization for large-scale production.

Technical Specifications

The following hard data points were extracted from the research paper detailing the material properties and performance metrics.

Parameter	Value	Unit	Context
Detector Material (Testbeam)	Electronic Grade scCVD	N/A	Primary sensor material
scCVD Thickness	440	µm	Sample dimension
scCVD Area	4.7 x 4.7	mm²	Sample dimension
3D Cell Size	150 x 150	µm²	Electrode geometry
Planar Strip Pitch	50	µm	Comparison geometry
3D Bias Voltage (Full Collection)	25	V	Key performance metric
Planar Bias Voltage (Full Collection)	> 450 (Tested at 500)	V	Comparison metric
Most Probable Charge (3D)	13,900	electrons (e)	Signal magnitude
Most Probable Charge (Planar)	13,800	electrons (e)	Signal magnitude
Laser Wavelength (scCVD)	800	nm	Femtosecond processing
Laser Pulse Duration (scCVD)	100	fs	Femtosecond processing
Laser Energy Density (scCVD)	2	J cm^-2	Processing parameter
Laser Velocity (scCVD)	20	µm s^-1	Channel growth speed
pCVD Thickness (Raman Study)	500	µm	Material for channel optimization
pCVD Laser Repetition Rate	200	kHz	Yb:YAG laser setup

Key Methodologies

The experiment relied on precise material selection, specialized laser processing, and comprehensive characterization techniques.

Material Selection: Electronic grade Single Crystal CVD (scCVD) diamond (440 µm thick) was used for the primary detector testbeam, while a 500 µm thick Polycrystalline CVD (pCVD) sample was used for laser parameter optimization via Raman spectroscopy.
3D Electrode Fabrication: Conductive channels were formed in the diamond bulk using a femtosecond laser (800 nm, 100 fs pulse duration) focused to a 4 µm spot size.
Phase Change Induction: The laser focal plane was moved from the back (“seed side”) to the front (“exit side”) of the sample at 20 µm s^-1, transforming the diamond lattice into a conductive combination of diamond-like carbon, amorphous carbon, and graphite.
Metalization Patterning: The sample surface was metallized using a custom mask to create three distinct test regions: a traditional planar strip detector, a 3D detector (with conductive channels), and a 3D phantom (metal pattern only, no channels).
Testbeam Measurement: The detector was exposed to 120 GeV pions at the CERN-SPS beam line. Signals were read out using a VA2 charge sensitive amplifier chip.
Charge Collection Analysis: Full charge collection was verified by comparing the Most Probable Charge (MPC) collected by the 3D structure (25 V bias) against the planar structure (> 450 V bias).
Channel Quality Assessment: Raman spectroscopy (440 nm laser) was used to analyze the ratio of the diamond peak (1332 nm^-1) height to the graphite G-peak (1580 nm^-1) height, quantifying the quality and composition of the conductive channels under various laser power/velocity settings.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-purity diamond substrates and specialized processing required to replicate and scale 3D diamond detector technology for future high-energy physics applications.

Applicable Materials

To replicate the high-performance results demonstrated in this paper, researchers require substrates with exceptional purity and crystalline quality.

Optical Grade Single Crystal Diamond (SCD): This material is the direct equivalent to the electronic grade scCVD used in the testbeam. 6CCVD provides high-purity SCD plates with guaranteed low nitrogen content, ensuring maximum Charge Collection Distance (CCD) necessary for optimal detector performance prior to 3D processing.
High-Quality Polycrystalline Diamond (PCD): For large-area tracking arrays or optimization studies (as performed in Section 3 of the paper), 6CCVD offers PCD wafers up to 125 mm in diameter. Our PCD materials provide the necessary thickness uniformity (up to 500 µm) and surface quality (Ra < 5 nm) required for large-scale, high-throughput laser processing.
Custom Thicknesses: The paper utilized 440 µm and 500 µm thick samples. 6CCVD routinely supplies SCD and PCD plates in the critical thickness range of 0.1 µm to 500 µm, allowing researchers to precisely match the required aspect ratio for 3D electrode geometry.

Customization Potential

The fabrication of 3D detectors requires highly specialized post-processing, which 6CCVD is equipped to support.

Requirement from Paper	6CCVD Capability	Technical Advantage
Custom Metalization Mask	Full in-house metalization capability	We offer deposition of Au, Pt, Pd, Ti, W, and Cu, allowing for precise replication of the complex strip and 3D cell patterns (150 x 150 µm² cells) used in the study.
High Surface Quality	Polishing to Ra < 1 nm (SCD)	Extremely low surface roughness ensures optimal lithography and metal adhesion, which is critical for the “seed side” and “exit side” contacts mentioned in the Raman analysis.
Custom Dimensions	Plates/wafers up to 125 mm (PCD)	Enables scaling of the 3D detector design from the small 4.7 x 4.7 mm² test samples to full-size tracking modules required for facilities like HL-LHC.
Substrate Preparation	Laser cutting and shaping	We provide substrates pre-cut to specific non-standard geometries, minimizing material waste and preparation time for subsequent femtosecond laser processing.

Engineering Support

The systematic difference in conductive channel structure between the seed and exit sides (as identified by Raman spectroscopy) highlights the complexity of 3D laser processing.

6CCVD’s in-house PhD team specializes in the structural and electronic properties of MPCVD diamond. We offer consultation services to assist researchers in selecting the optimal SCD or PCD grade to minimize defects and maximize charge carrier mobility for similar High-Energy Particle Tracking projects.
We provide detailed material characterization data (e.g., nitrogen concentration, crystalline orientation, surface termination) to ensure the substrate is perfectly prepared for specialized post-processing techniques like femtosecond laser graphitization.
Global logistics are handled efficiently, with DDU default shipping and DDP options available worldwide, ensuring rapid delivery of critical materials to international research collaborations.

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

Tech Support

Original Source

DOI: https://doi.org/10.1016/j.nima.2015.09.079