Bright Single-Photon Emitting Diodes Based on the Silicon-Vacancy Center in AlN/Diamond Heterostructures

At a Glance

Metadata	Details
Publication Date	2020-02-19
Journal	Nanomaterials
Authors	Igor A. Khramtsov, Dmitry Yu. Fedyanin
Institutions	Moscow Institute of Physics and Technology
Citations	16
Analysis	Full AI Review Included

Executive Summary

This research proposes and numerically validates a novel, high-brightness Single-Photon Emitting Diode (SPED) based on a Silicon-Vacancy (SiV) center within an n-AlN/i-diamond/p-diamond heterostructure, designed for room-temperature quantum applications.

Performance Breakthrough: The maximum simulated Single-Photon Electroluminescence (SPEL) rate reaches 3.9 x 10⁶ cps, which is five times higher than the maximum rate achievable in conventional diamond p-i-n diodes utilizing the superinjection effect.
Electrical Excitation Solution: The device overcomes the critical challenge of low free electron density in diamond by using n-type Aluminum Nitride (AlN) as an efficient electron injector.
Tunneling Mechanism: Despite a large Conduction Band Offset (CBO) of 0.9 eV at the AlN/diamond interface, high forward bias (< 6 V) creates an intense electric field (> 5 x 10⁶ V/cm), reducing the barrier width to < 3 nm, enabling efficient quantum tunneling of electrons into the intrinsic diamond layer.
Nanoscale Scalability: The high SPEL rate is achieved in a truly nanoscale architecture (300 nm i-diamond layer), making it suitable for integration into complex nano-optoelectronic circuits.
Interface Robustness: The device performance remains robust against typical interface defects. Efficient electron injection is maintained even with recombination center densities up to 10¹⁰ cm^-2 at the 0.9 eV CBO interface.
Future Potential: If the SiV center’s quantum efficiency were 100% (instead of the current 30%), the maximum theoretical SPEL rate could exceed 40 Mcps.

Technical Specifications

Parameter	Value	Unit	Context
Maximum SPEL Rate (Simulated)	3.9 x 10⁶	cps	At 500 A/cm² current density
SPEL Rate Enhancement	5x Higher	Ratio	Compared to diamond p-i-n superinjection diodes
SiV Center Emission Wavelength	738	nm	Room temperature operation
Operating Bias Voltage (High Rate)	< 6	V	Required for efficient tunneling injection
Maximum Current Density	100	A/cm²	Achieved at moderate bias voltages
Conduction Band Offset (CBO)	0.9	eV	AlN/Diamond interface (C-N polarity, worst case)
Electric Field at Junction (High Bias)	> 5 x 10⁶	V/cm	Facilitates quantum tunneling
Electron Tunneling Barrier Width	< 3	nm	Under high forward bias
i-Diamond Layer Thickness	300	nm	Nanoscale device dimension
Injected Electron Density (i-region)	> 3 x 10¹⁵	cm^-3	Exceeds bulk AlN electron density
SiV Shelving State Lifetime (tau_s)	100	ns	Limits maximum SPEL rate (based on Ref. 36)
SiV Quantum Efficiency (QE)	30	%	Based on recent experimental results (Ref. 33)
AlN Doping (n-type, Si)	10¹⁸	cm^-3	Donor compensation ratio 10%
Diamond Doping (p-type, B)	10¹⁸	cm^-3	Donor compensation ratio 1%
Interface Defect Tolerance (0.9 eV CBO)	< 10¹⁰	cm^-2	Density of recombination centers that does not affect performance

Key Methodologies

The study relies on a comprehensive theoretical and numerical approach using self-consistent 2D simulations to model carrier transport and single-photon emission kinetics in the proposed heterostructure.

Device Architecture Modeling:
- The structure modeled is an n-AlN/i-diamond/p-diamond heterojunction SPED, with the SiV color center positioned in the 300 nm intrinsic (i-type) diamond region.
- Material parameters (effective masses, mobilities, activation energies) for diamond and AlN were incorporated based on established literature.
Carrier Transport Simulation:
- Self-consistent 2D numerical simulations were performed using the Atlas Silvaco software package.
- The simulation calculated the distribution of electron and hole densities (n and p) and current flow (J) across the heterostructure under varying forward bias voltages (up to 6.5 V).
Quantum Tunneling Analysis:
- Due to the large 0.9 eV Conduction Band Offset (CBO), electron injection was dominated by quantum tunneling rather than thermionic emission.
- The tunneling current density (J) was calculated using the WKB approximation, incorporating the transparency T(E) of the potential barrier, which is highly sensitive to the electric field gradient at the junction.
SPEL Rate Calculation:
- The single-photon electroluminescence rate (R_SPEL) was determined using the steady-state rate equation (Eq 1), which depends critically on the local densities of injected electrons (n) and holes (p) in the vicinity of the SiV center.
- The calculation incorporated known SiV parameters, including the radiative lifetime (tau_r), non-radiative lifetime (tau_nr), and the long lifetime of the shelving state (tau_s ~ 100 ns).
Interface Defect Impact Modeling:
- The effect of charged defects at the non-ideal AlN/diamond interface was modeled by introducing recombination centers (N^int_rec).
- The interface recombination rate (U_int) was calculated, showing how defects deplete accumulated electrons in AlN, thereby increasing the effective barrier width and suppressing tunneling injection.

Commercial Applications

The development of bright, electrically driven, room-temperature single-photon sources based on SiV centers in AlN/diamond heterostructures is crucial for the practical realization of integrated quantum technologies.

Integrated Quantum Photonics:
- Enables the creation of scalable, on-chip quantum circuits where numerous SPSs can be individually addressed and triggered using low-voltage electrical signals.
Quantum Key Distribution (QKD) Systems:
- Provides high-rate, room-temperature single-photon generation necessary for robust and secure fiber-optic communication networks.
Solid-State Quantum Computing:
- Electrically pumped SiV centers serve as highly coherent qubits and spin-photon interfaces, essential for scalable solid-state quantum processors operating outside cryogenic environments.
Advanced Quantum Sensing:
- Integration of SiV-based sensors (e.g., for magnetic fields or temperature) into compact, electrically controlled arrays, leveraging diamond’s superior material properties.
Nano-Optoelectronic Devices:
- The demonstrated nanoscale device architecture provides a blueprint for manufacturing compact, energy-efficient optoelectronic components compatible with existing semiconductor fabrication processes.

View Original Abstract

Practical implementation of many quantum information and sensing technologies relies on the ability to efficiently generate and manipulate single-photon photons under ambient conditions. Color centers in diamond, such as the silicon-vacancy (SiV) center, have recently emerged as extremely attractive single-photon emitters for room temperature applications. However, diamond is a material at the interface between insulators and semiconductors. Therefore, it is extremely difficult to excite color centers electrically and consequently develop bright and efficient electrically driven single-photon sources. Here, using a comprehensive theoretical approach, we propose and numerically demonstrate a concept of a single-photon emitting diode (SPED) based on a SiV center in a nanoscale AlN/diamond heterojunction device. We find that in spite of the high potential barrier for electrons in AlN at the AlN/diamond heterojunction, under forward bias, electrons can be efficiently injected from AlN into the i-type diamond region of the n-AlN/i-diamond/p-diamond heterostructure, which ensures bright single-photon electroluminescence (SPEL) of the SiV center located in the i-type diamond region. The maximum SPEL rate is more than five times higher than what can be achieved in SPEDs based on diamond p-i-n diodes. Despite the high density of defects at the AlN/diamond interface, the SPEL rate can reach about 4 Mcps, which coincides with the limit imposed by the quantum efficiency and the lifetime of the shelving state of the SiV center. These findings provide new insights into the development of bright room-temperature electrically driven single-photon sources for quantum information technologies and, we believe, stimulate further research in this area.

Tech Support

Original Source

DOI: https://doi.org/10.3390/nano10020361

References

2015 - Electrically Driven Quantum Light Sources [Crossref]
2012 - Engineered quantum dot single-photon sources [Crossref]
2011 - Diamond-based single-photon emitters [Crossref]
2016 - Quantum nanophotonics in diamond [Crossref]
2019 - Quantum nanophotonics with group IV defects in diamond [Crossref]
2015 - Robust luminescence of the silicon-vacancy center in diamond at high temperatures [Crossref]
2014 - Multiple intrinsically identical single-photon emitters in the solid state [Crossref]
2016 - Ultrabright single-photon source on diamond with electrical pumping at room and high temperatures [Crossref]
2019 - Superinjection in Diamond p-i-n Diodes: Bright Single-Photon Electroluminescence of Color Centers Beyond the Doping Limit [Crossref]