Light emission from color centers in phosphorus-doped diamond

At a Glance

Metadata	Details
Publication Date	2022-01-01
Journal	EPJ Web of Conferences
Authors	Florian Sledz, Assegid M. Flatae, S. Lagomarsino, Savino Piccolomo, Shannon S. Nicley
Institutions	Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, University of Siegen
Analysis	Full AI Review Included

Technical Documentation & Analysis: Electroluminescent Diamond Emitters

Executive Summary

This research successfully demonstrates the creation and characterization of single Silicon-Vacancy (SiV) color centers within Phosphorus-doped (n-type) Single Crystal Diamond (SCD) films grown via Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD). This work is critical for advancing diamond-based optoelectronics, specifically high-temperature Light Emitting Diodes (LEDs) and single-photon emitters (SPEs).

Core Value Proposition: Simplification of electroluminescent device architecture by utilizing n-type diamond and Schottky contacts, eliminating the need for complex p-i-n structures.
Material Achievement: Successful growth of P-doped SCD films using PH₃/CH₄ ratios up to 20,000 ppm, requiring extremely high gas purity (< 1 ppb N₂) to minimize competing Nitrogen-Vacancy (NV) center formation.
SiV Center Creation: SiV centers were introduced via shallow Si-ion implantation (< 200 nm depth) followed by high-temperature (1200 °C) high-vacuum annealing (~10^-7 mbar).
Quantum Potential: Single-photon emission from SiV centers was confirmed in low-nitrogen content samples, although further low-temperature studies are recommended for quantum applications.
Classical Electronics Potential: SiV centers demonstrated photostability up to 100 °C, confirming the system’s promise for high-temperature LEDs that maintain performance where conventional LEDs degrade.
6CCVD Relevance: This research relies heavily on high-purity, low-defect SCD substrates and precise post-growth processing, areas where 6CCVD offers industry-leading customization and quality control.

Technical Specifications

Parameter	Value	Unit	Context
Growth Method	MWPECVD	N/A	Fabrication of P-doped SCD films
Methane Concentration (CH₄)	0.09% to 0.15%	N/A	Concentration in H₂ plasma
Phosphine/Methane Ratio (PH₃/CH₄)	Up to 20,000	ppm	Used for P-doping gradient/constant doping
Gas Purity (H₂/CH₄)	< 1	ppb	Required 9 N purity to minimize N-doping
Si-Ion Implantation Energy	Few tens of	keV	Achieved using Al metal foils to reduce 3 MV source
Implantation Depth	< 200	nm	Target depth for shallow SiV creation
Si-Ion Fluence Range	10⁷ to 10¹⁴	cm^-2	Tested range for SiV density control
SiV Activation Annealing Temperature	1200	°C	Required for SiV center activation
SiV Activation Annealing Pressure	~10^-7	mbar	High-vacuum conditions
SiV Photostability	Up to 100	°C	Tested operational temperature range
P-Donor Activation Energy	~0.6	eV	Requires high temperature for efficient electrical operation

Key Methodologies

The successful creation of SiV centers in n-type diamond relied on precise control over CVD growth parameters and subsequent high-temperature processing steps:

P-Doped Diamond Growth: Single-crystal diamond films were grown homo-epitaxially using a 2.45 GHz MWPECVD reactor.
Doping Control: Phosphorus (P) doping was achieved by introducing PH₃ gas, with PH₃/CH₄ ratios adjusted in steps up to 20,000 ppm to create both constant and gradient doping profiles.
Nitrogen Minimization: Extreme gas purity was maintained, filtering H₂ and CH₄ gasses to < 1 ppb (9 N purity) to ensure low background nitrogen content, which is critical for minimizing competing NV center fluorescence.
Shallow Si-Ion Implantation: Si ions were implanted using a 3 MV Tandetron accelerator. Aluminum foils were used to reduce the ion energy to a few tens of keV, ensuring a shallow implantation depth of < 200 nm from the surface.
SiV Activation Annealing: Samples were annealed in a custom-designed furnace at 1200 °C under high-vacuum conditions (~10^-7 mbar) to activate the implanted SiV color centers.

6CCVD Solutions & Capabilities

This research highlights the stringent material requirements necessary for developing diamond-based quantum and high-temperature optoelectronics. 6CCVD is uniquely positioned to supply the high-purity, custom-processed diamond materials required to replicate and advance this work.

Applicable Materials

To replicate the high-performance SiV centers and minimize background noise, researchers require diamond with extremely low intrinsic defects.

Optical Grade Single Crystal Diamond (SCD): Essential for providing the low-nitrogen host environment required to suppress NV-related fluorescence background (as noted in the paper). 6CCVD guarantees high-purity SCD necessary for high-fidelity quantum emitter studies.
Boron-Doped Diamond (BDD): While the paper utilized P-doping for n-type conductivity, 6CCVD offers highly controlled Boron-Doped Diamond (BDD) for p-type or heavily doped metallic applications, providing a complementary material for p-i-n or complex junction structures.

Customization Potential

The success of this methodology depends on precise control over film thickness, surface quality for implantation, and subsequent metalization for electrical excitation.

Research Requirement	6CCVD Capability	Sales Advantage
Substrate Quality & Dimensions	Custom Plates/Wafers up to 125 mm	Provides large-area PCD or SCD substrates for scaling up device fabrication and high-volume processing.
Precise Film Thickness	SCD/PCD Thickness: 0.1 µm to 500 µm	Allows engineers to specify the exact epitaxial layer thickness required for optimal charge transport and SiV placement relative to the surface/contacts.
Surface Preparation for Implantation	SCD Polishing: Ra < 1 nm	Ultra-smooth surfaces ensure uniform, shallow ion implantation (< 200 nm) and minimize surface defects that can degrade emitter coherence.
Electrical Contact Integration	In-House Metalization Services	6CCVD offers custom deposition of Au, Pt, Pd, Ti, W, and Cu, enabling rapid prototyping of the Schottky diodes or ohmic contacts required for electrical excitation of the SiV centers.
Global Logistics	Global Shipping (DDU/DDP)	Ensures rapid and reliable delivery of custom materials worldwide, supporting international research collaborations.

Engineering Support

6CCVD’s in-house PhD team specializes in optimizing MPCVD growth recipes for specific color centers and semiconductor applications. We offer consultation services for:

Material Selection: Assisting researchers in selecting the optimal SCD grade (e.g., low-N, high-thermal conductivity) for similar Electroluminescent Single-Photon Emitter projects.
Post-Processing Optimization: Providing guidance on surface termination and metalization schemes to achieve low-resistance ohmic contacts or precise Schottky barriers necessary for efficient hole injection into n-type diamond.
High-Temperature Electronics: Supporting the development of diamond-based devices designed for extreme environments, leveraging diamond’s superior thermal properties for high-temperature LED and power electronics applications.

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

View Original Abstract

Light emission from color centers in diamond is being extensively investigated for developing, among other quantum devices, single-photon sources operating at room temperature. By doping diamond with phosphorus, one obtains an n-type semiconductor, which can be exploited for the electrical excitation of color centers. Here, we discuss the optical properties of color centers in phosphorus-doped diamond, especially the silicon-vacancy center, presenting the single-photon emission characteristics and the temperature dependence aiming for electroluminescent single-photon emitting devices.

Tech Support

Original Source

DOI: https://doi.org/10.1051/epjconf/202226609008