Novel Sensors for Particle Tracking - a Contribution to the Snowmassn Community Planning Exercise of 2021

At a Glance

Metadata	Details
Publication Date	2022-02-23
Journal	arXiv (Cornell University)
Authors	S. Spagnolo, S. Kim, J. Metcalfe, A. Sumant
Institutions	Centre de Nanosciences et de Nanotechnologies, Center for Nanoscale Science and Technology
Citations	1
Analysis	Full AI Review Included

Novel Sensors for Particle Tracking: Leveraging MPCVD Diamond for Extreme Environments

This technical documentation, prepared by 6CCVD Material Science & Engineering, analyzes the requirements and achievements detailed in the research paper, “Novel Sensors for Particle Tracking,” focusing on the application of 3D Single Crystal Diamond (SCD) detectors in future High Energy Physics (HEP) environments.

Executive Summary

6CCVD is positioned to supply the high-ppurity Single Crystal Diamond (SCD) materials required to meet the extreme radiation hardness and dimensional tolerances demonstrated for next-generation particle trackers.

Radiation Hardness: The research targets a detector platform essentially immune to radiation doses up to $10^{17} \text{ hadrons/cm}^2$, exceeding projected doses for HL-LHC experiments.
3D Diamond Geometry: Utilizes column-like electrodes placed within the diamond bulk to reduce charge carrier drift distance far below the mean free path, thereby compensating for signal loss in trap-dominated (highly irradiated) materials.
Advanced Microstructuring: Electrodes are created using femtosecond laser microstructuring (130 fs, 800 nm, 2 µm spot) to convert diamond into an electrically resistive mixed carbon phase.
Performance Metrics: Achieved high column yield ($\ge 99.8%$) with small column diameters ($2.6 \text{ µm}$) and controllable column resistivity ($0.1 - 1 \text{ }\Omega\text{cm}$).
Irradiation Resilience: Initial tests showed that after a fluence of $3.5 \times 10^{15} \text{n}/\text{cm}^2$, the 3D diamond structure exhibited more than three times less charge loss compared to equivalent planar diamond detectors.
High-Resolution Targets: Design goals include reducing cell size to $25 \text{ µm} \times 25 \text{ µm}$, yielding a maximum drift distance of $25 \text{ µm}$, optimizing vertexing and timing resolution.

Technical Specifications

The following hard data points relate directly to the design and performance requirements for diamond and related 3D sensor technologies discussed in the paper.

Parameter	Value	Unit	Context
Diamond Radiation Hardness Goal	$10^{17}$	hadrons/cm²	Target dose for 3D diamond detector operational immunity.
Initial Test Fluence (Diamond)	$3.5 \times 10^{15}$	n/cm²	Fluence level where 3D diamond demonstrated superior charge collection.
Diamond 3D Cell Size (Current)	$50 \times 50$	µm²	Cell dimensions utilized in current prototype sensors.
Diamond 3D Cell Size (Proposed)	$25 \times 25$	µm²	Proposed dimensions for enhanced resolution/drift distance optimization.
Laser Pulse Duration	130	fs	Required duration for focused femtosecond laser microstructuring.
Laser Wavelength	800	nm	Laser used for creating internal diamond columns.
Laser Focus Spot Diameter	2	µm	Required spot size to achieve diamond phase conversion.
Achieved Column Diameter	2.6	µm	Small diameter of the internal electrically resistive electrode.
Achieved Column Yield	$\ge 99.8$	%	High fabrication yield achieved using Spatial Light Modulator (SLM).
Column Resistivity	$0.1 - 1$	Ωcm	Resistivity of the laser-modified carbon phase material.
Maximum Drift Distance (Small Cell)	25	µm	Maximum travel distance for charge carriers in $25 \text{ µm} \times 25 \text{ µm}$ cells.
Silicon Timing Resolution Goal	10	ps	Target timing resolution for advanced 3D Silicon sensors.
HL-LHC Silicon Fluence	$2.3 \times 10^{16}$	neq/cm²	Expected 10-year integrated fluence for innermost silicon tracking volume.

Key Methodologies

The core innovation in diamond tracking relies on internal microstructuring to achieve optimal drift distance and high radiation tolerance.

Material Selection: Use of high-purity SCD substrates to provide the basic semiconductor stopping medium for charged particles.
Internal Electrode Generation: Employing a 130 fs pulsed laser at 800 nm, focused to a 2 µm spot diameter, to selectively microstructure the bulk diamond.
Phase Conversion: The focused energy density converts the diamond structure into an electrically resistive mixture of different carbon phases, forming the conductive column electrodes.
Precision Fabrication: Utilization of a Spatial Light Modulator (SLM) to correct spherical aberrations, ensuring high column yield ($\ge 99.8%$) and tight diameter control ($2.6 \text{ µm}$).
Drift Distance Optimization: Designing the cell pitch (e.g., $50 \text{ µm}$ or $25 \text{ µm}$) such that the maximum charge carrier drift distance is significantly less than the radiation-induced mean free path ($\lt 50 \text{ µm}$), thereby maximizing signal collection post-irradiation.
Planar Processing: Subsequent steps include the application of contact metalization layers (implied, not fully specified in paper) compatible with high energy physics readout systems.

6CCVD Solutions & Capabilities: Enabling Extreme Environment Diamond Detectors

The successful replication and scaling of these novel 3D diamond detectors depend critically on the quality, purity, and custom preparation of the MPCVD diamond substrate. 6CCVD specializes in providing the precise material engineering required for this advanced research.

Applicable Materials

To replicate or advance the 3D diamond detector research for HEP, researchers require defect-free, high-purity Single Crystal Diamond (SCD) that maximizes charge carrier mobility and initial signal size before irradiation.

Material Recommendation: Optical Grade SCD (Undoped). 6CCVD provides high-purity SCD wafers with low native defect density, ensuring optimal starting charge carrier properties essential for particle detection applications where maximizing charge collection efficiency is paramount.
Substrate Capability: We offer SCD wafers in thicknesses suitable for high-energy tracking applications, ranging from $0.1 \text{ µm}$ up to $500 \text{ µm}$, allowing researchers to tailor the depletion depth independently of the 3D electrode geometry.

Customization Potential

The paper emphasizes the need for small pitch sizes ($25 \text{ µm} \times 25 \text{ µm}$) and optimized device geometry (e.g., slim edges, internal electrode placement). 6CCVD’s advanced processing capabilities directly support these requirements:

6CCVD Capability	Research Requirement Addressed	Value Proposition
Custom Wafer Dimensions	Need for large area coverage (up to $125 \text{ mm}$ PCD/SCD) and optimized edge geometry (e.g., $150 \text{ µm}$ slim edges mentioned in the paper).	Provides large-scale, custom-cut substrates ready for advanced laser microstructuring and system integration.
Ultra-Smooth Polishing	Requirements for low surface roughness for subsequent semiconductor processing steps (implied compatibility with CMOS/wafer bonding).	Standard Ra < 1nm polishing on SCD ensures clean interfaces for metalization and bonding, crucial for high-efficiency detectors.
Custom Metalization Schemes	Need for electrical contacts/readout pads compatible with detector electronics (Au, Ti/Pt/Au contact systems are typical).	Internal capability for depositing $\text{Ti, Pt, Au, Pd, W, or Cu}$ films enables optimized contact resistivity for high-speed signal extraction from the 3D electrodes.

Engineering Support

The complexity of shifting from planar to 3D diamond detection architecture requires specialized material knowledge regarding bulk properties and laser interaction.

Application Focus: 6CCVD’s in-house PhD engineering team can assist with material selection, optimizing SCD crystallographic orientation and controlling nitrogen/defect concentration to ensure maximum effectiveness during the femtosecond laser microstructuring process, vital for similar High Energy Physics Tracking projects.
Global Supply Chain: We offer reliable global shipping (DDU default, DDP available), ensuring researchers worldwide receive critical, specialized diamond substrates promptly and securely.

For custom specifications or material consultation regarding 3D diamond fabrication and high-flux detector projects, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Five contemporary technologies are discussed in the context of their\npotential roles in particle tracking for future high energy physics\napplications. These include sensors of the 3D configuration, in both diamond\nand silicon, submicron-dimension pixels, thin film detectors, and scintillating\nquantum dots in gallium arsenide. Drivers of the technologies include radiation\nhardness, excellent position, vertex, and timing resolution, simplified\nintegration, and optimized power, cost, and material.\n

Tech Support

Original Source

DOI: https://doi.org/10.48550/arxiv.2202.11828