Electrical excitation of silicon-vacancy centers in single crystal diamond

At a Glance

Metadata	Details
Publication Date	2015-04-27
Journal	Applied Physics Letters
Authors	Amanuel M. Berhane, Sumin Choi, Hiromitsu Kato, Toshiharu Makino, Norikazu Mizuochi
Institutions	University of Technology Sydney, Osaka University
Citations	37
Analysis	Full AI Review Included

Technical Documentation & Analysis: Electrically Driven SiV Centers in SCD

Executive Summary

This research demonstrates a critical step toward integrated quantum devices by achieving stable, room-temperature electrical excitation of Silicon-Vacancy (SiV)^- centers in single crystal diamond (SCD).

Core Achievement: First demonstration of stable electroluminescence (EL) from the negatively charged SiV^- defect in SCD, a key requirement for scalable nanophotonics.
Device Architecture: A custom p-i-n SCD diode structure was fabricated, utilizing a 10 µm intrinsic (i) layer for targeted Si ion implantation.
Defect Engineering: SiV^- centers were generated via 1.5 MeV ion implantation, ensuring the defects resided predominantly within the intrinsic region of the diode.
Spectral Confirmation: Both EL and photoluminescence (PL) measurements confirmed the characteristic 738 nm Zero Phonon Line (ZPL) corresponding exclusively to the (SiV)^- charge state.
Operational Stability: The device exhibited stable EL emission for over 6 minutes at room temperature, operating at a current density of 7.9 A/cm².
Scalability Potential: This work validates the use of electrically driven SiV^- centers as highly promising building blocks for integrated quantum information processing and on-chip photonics.

Technical Specifications

The following hard data points were extracted from the research paper detailing the material structure and operational performance of the SiV^- SCD diode.

Parameter	Value	Unit	Context
Target Color Center	SiV^-	N/A	Negatively charged Silicon-Vacancy
Zero Phonon Line (ZPL)	738	nm	Emission wavelength confirmed by EL and PL
p-type Substrate Thickness	0.5	mm	Starting material layer
Intrinsic (i) Layer Thickness	10	µm	MPCVD grown layer for defect placement
n-type Mesa Thickness	0.5	µm	Top layer of PIN diode
Ion Implantation Energy (Si)	1.5	MeV	Used to place Si atoms at depth
Ion Implantation Dose	1 x 10¹¹	atoms/cm²	Low dose over the sample area
End of Range (SRIM Estimate)	820	nm	Estimated depth of Si atom concentration
Forward Threshold Voltage	43	V	Required for diode rectification
Threshold Current Density	7.9	A/cm²	Corresponds to 0.89 mA forward current
Maximum EL Count Rate (r_sat)	5.7	kcounts/s	Achieved at saturation current (I_sat)
Metalization Stack	Ti/Pt/Au	N/A	30 nm Ti / 100 nm Pt / 200 nm Au

Key Methodologies

The following steps outline the fabrication and characterization process used to create the electrically excited SiV^- devices:

Material Growth: A Single Crystal Diamond (SCD) p-i-n diode structure was grown via MPCVD. The structure consisted of a 0.5 mm p-type substrate, a 10 µm intrinsic layer, and a 0.5 µm n-type diamond mesa.
Defect Introduction: Silicon (Si) ion implantation was performed at 1.5 MeV with a low dose of 1 x 10¹¹ atoms/cm², specifically targeting the intrinsic (i) layer of the diode structure.
Device Definition: Circular mesas (pillars) with a 120 µm diameter were fabricated to define the active area of the PIN diode.
Contact Metalization: A multi-layer metal stack (30 nm Ti / 100 nm Pt / 200 nm Au) was deposited onto both the n-type and p-type sides of the device to serve as contact electrodes.
Electrical Characterization: I-V rectification curves were measured, confirming a forward threshold voltage of 43 V and a threshold current density of 7.9 A/cm².
Optical Characterization: Electroluminescence (EL) was measured using an external voltage source and a scanning confocal microscope. Photoluminescence (PL) was measured using a continuous wave 532 nm excitation laser for comparison.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-purity, custom-engineered diamond materials and fabrication services necessary to replicate, optimize, and scale the SiV^- quantum devices demonstrated in this research.

Applicable Materials for Quantum Device Replication

The successful fabrication of the p-i-n diode relies on precise control over material purity, thickness, and doping profiles.

Material Requirement (Paper)	6CCVD Solution	Customization & Advantage
Intrinsic (i) Layer (10 µm)	Electronic Grade Single Crystal Diamond (SCD)	Ultra-low nitrogen concentration (ppm level) essential for high-coherence color centers like SiV. We offer SCD thickness control from 0.1 µm up to 500 µm.
Substrate Material (0.5 mm p-type)	High-Purity SCD Substrates	We supply robust substrates up to 10 mm thick, suitable for subsequent epitaxial growth of doped layers (p-type or n-type) or direct ion implantation.
Doping Requirements	Boron-Doped Diamond (BDD)	While the paper used p-type (likely Boron-doped) and n-type (Phosphorous-doped) layers, 6CCVD specializes in highly controlled BDD for p-type conductivity, crucial for optimizing charge injection dynamics.

Customization Potential & Fabrication Services

6CCVD’s in-house capabilities directly address the complex fabrication steps required for integrated diamond quantum devices.

Custom Dimensions and Thickness: The paper utilized a 0.5 mm thick substrate and a 10 µm intrinsic layer. 6CCVD provides custom SCD plates and wafers up to 125 mm (PCD) and substrates up to 10 mm thick, ensuring compatibility with standard semiconductor processing equipment.
Precision Metalization Matching: The research utilized a specific Ti/Pt/Au contact stack (30 nm Ti / 100 nm Pt / 200 nm Au). 6CCVD offers internal metalization services, including Au, Pt, Pd, Ti, W, and Cu, allowing researchers to precisely replicate or optimize ohmic contacts for charge injection efficiency.
Surface Quality: Achieving high-quality contacts and minimizing surface defects is critical for diode performance. 6CCVD guarantees Ra < 1 nm polishing for SCD, providing the atomically smooth surface necessary for reliable metal deposition and subsequent processing.
Post-Processing Services: We offer custom laser cutting and shaping services, enabling the precise definition of the 120 µm diameter circular mesas and other complex geometries required for nanophotonics integration.

Engineering Support

6CCVD’s in-house PhD team specializes in material selection and optimization for quantum applications. We provide consultation on:

Defect Engineering: Assisting researchers in selecting the optimal SCD material purity and crystal orientation for efficient SiV creation via ion implantation or in-situ growth.
Charge State Control: Advising on the use of Boron-Doped Diamond (BDD) layers and intrinsic layer thickness to control the Fermi level and stabilize the desired (SiV)^- charge state for enhanced EL efficiency.
Integrated Nanophotonics: Supporting the design and fabrication of diamond structures (e.g., photonic crystal cavities, waveguides) using our high-quality SCD to enhance photon collection efficiency for similar electrically driven color center projects.

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

View Original Abstract

Electrically driven emission from negatively charged silicon-vacancy (SiV)− centers in single crystal diamond is demonstrated. The SiV centers were generated using ion implantation into an i region of a p-i-n single crystal diamond diode. Both electroluminescence and the photoluminescence signals exhibit the typical emission that is attributed to the (SiV)− centers. Under forward and reversed biased PL measurements, no signal from the neutral (SiV)0 defect could be observed. The realization of electrically driven (SiV)− emission is promising for scalable nanophotonics devices employing color centers in single crystal diamond.

Tech Support

Original Source

DOI: https://doi.org/10.1063/1.4919388