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Project titleHighly efficient electrically-driven single-photon sources based on color centers in diamond and silicon carbide
Project LeadFedyanin Dmitry
AffiliationMoscow Institute of Physics and Technology,
Implementation period2017 - 2019
Research area 09 - ENGINEERING SCIENCES, 09-707 - Hardware for quantum computers and communication systems
KeywordsSingle-photon source, electrical pumping, single-photon emitting diode, optical nanostructures, color centers, nanoscale diode, point defects in the crystal lattice of diamond, defects in silicon carbide, single-photon emission dynamics, quantum computers, quantum cryptography, quantum optoelectronics at room temperature
The project is focused on the study of single-photon/single-electron processes in defects of the crystal lattice of diamond and silicon carbide and on the development of electrically pumped true single-photon sources, which are characterized by high intensity of single-photon emission, high energy efficiency and ability to generate single photons at room temperature. Сolor centers, in the crystal lattice of diamond and other wide bandgap semiconductor materials, such as silicon carbide, gallium nitride, zinc oxide and hexagonal boron nitride, are considered to be the most promising candidates for the role of electrically driven single-photon sources thanks to a narrow linewidth of their emission spectrum and bright luminescence at room temperature. However, the physics behind the process of single-photon emission from color centers under electrical pumping is poorly understood, and the fundamental limits of electrically driven single-photon sources based on color centers are not yet established. We will study the mechanism of single-photon emission under electrical pumping from color centers in diamond and silicon carbide and develop novel and efficient schemes of electrical pumping. We expect that this will give the possibility to increase the single-photon emission rate by three orders of magnitude from the levels, which were recently observed in the experiments. We will also present characteristics of electrically pumped single-photon sources based color center in diamond and silicon carbide at room and higher temperatures and establish their fundamental and technical limitations. The successful solution of the problems posed in the project will create the basis for the transition to quantum cryptography schemes based on true single-photon sources (instead of attenuated lasers), which will lead to an increase in the security level of quantum key distribution schemes (QKDs). Moreover, increasing the brightness and efficiency of single-photon sources based on color centers in diamond and silicon carbide will make them attractive for implementing practical schemes of linear optical quantum computation, the most promising technology of quantum computing which is potentially capable of operation under standard conditions.
We expect that at the end of this project, we will demonstrate significant results for both fundamental science and practical applications. It should be noted that practical implementation of quantum information technologies, including secure communication lines based on quantum cryptography, require devices and components capable of operating under normal conditions. However, this task is still a challenge for quantum optics and optoelectronics, where most effects can be observed only at cryogenic and liquid helium temperatures. In addition, the components should be characterized by high efficiency and be capable of integrating into large-scale circuits. To satisfy these requirements, one needs to move to electrically pumped devices. Color centers in diamond and silicon carbide are the best candidates for true single-photon sources operating at room temperature [A. Boretti, L. Rosa, A. Mackie and S. Castelletto, Adv. Optical Mater. 3, 1012-1033 (2015)]. We also expect that the output characteristics of the electrically driven single-photon sources based on color centers will be an order of magnitude higher than that of the previously developed single-photon sources with both electrical and optical pumping. This feature makes color centers in diamond and silicon carbide extremely attractive for the development of practical single-photon sources for secure communication lines based on quantum cryptography and quantum information systems. One of the main results of this research project will be new theoretical models which give the possibility to describe electrically pumped single-photon sources based on color centers in diamond and silicon carbide and predict their characteristics, optimize them and improve them. Another important result will be the development of new configurations of true single-photon sources that are characterized by a high intensity of single-photon emission of 10^7-10^9 photons per second when pumped at temperatures above 300 K. To achieve high brightness of electrically-pumped single-photon sources on diamond and silicon carbide, we will develop a plasmon nanoantenna, which increases both the quantum efficiency of the color centers due to the Purcell effect and the collection efficiency. We expect to introduce a nanoantenna which ensures collection efficiency of more than 70% and maintains the size of the single-photon source at the nanometer level. To further decrease the dimensions of the single-photon sources and improve their characteristics, we will introduce a novel pumping schemes based on a Schottky contact. This approach will allow injecting minority carriers to the semiconductor directly from the metal contact. Therefore, one can use either n-type, p-type substrate (this depends on the type of the contact) instead of the expensive epitaxial p-i-n and p-n structures. For numerical simulations of the proposed single-photon sources, we will use nextnano software and our own scientific code. Using the results of numerical simulations, we will obtain both steady-state and dynamic characteristics of the single-photon sources compare them with the experimental results. The level of the results of our research will be at the world top level. Furthermore, many results will be “pioneering” and will facilitate practical implementation of single-photon sources in secure communication lines based on quantum cryptography and quantum information systems. We expect to publish our results in the leading scientific journals, such as Nano Letters (impact factor 13,779), ACS Photonics (5,404 ), Scientific Reports (5,228), Advanced Optical Materials (5.359), Optics Letters (3,040), etc., and present them in international conferences. At the end of the project, we will publish at least 10 papers in peer-review scientific journals with an impact factor of greater than 2,5: 2 papers in the first year of the project, 3 in the second year and 5 in the third year.
Annotation of the results obtained in 2017
In spite of the rapid development of quantum photonic technologies, there are still no bright and efficient sources of single photons that can operate under standard conditions. To date, the most promising candidates for the role of practical single-photon sources are color centers in diamond and related wide-bandgap semiconductors. Color centers are point defects in the crystal lattice. Their optical properties are close to that of isolated atoms. At the same time, color centers, as well as quantum dots, can be excited electrically demonstrating remarkable emission characteristics at room and higher temperatures. However, the single-photon electroluminescence of color centers has been poorly studied, and their potential for practical application is not yet known. In the first stage of the project, we have developed models and theoretical approaches for numerical simulations of the single-photon electroluminescence of color centers in diamond and silicon carbide. We have developed the software for the numerical simulation of the single-photon electroluminescence of color centers in p-n and p-i-n structures. The results of the numerical simulations give the possibility to accurately predict the emission properties of electrically pumped color centers. The theoretical studies of silicon carbide single-photon emitting diodes have shown that the single-photon emission rate can be increased to 0.1-10 Gcps, which lays the foundation for the development of high-bandwidth quantum communications. Our numerical studies of the electrically pumped single-photon sources on diamond revealed a novel effect, i.e., the superinjection effect in diamond homojunctions. Previously, it was believed that the superinjection effect is a distinct feature of semiconductor heterostructures. However, we have shown that diamond-based diodes can operate in the regimes that are unreachable by conventional semiconductors, which allows to reach the superinjection conditions. Our simulations show that it is possible to create a density of electrons in the i-region of the diamond p-i-n diode that is three orders of magnitude higher than the density of electrons in the n-type injection region. This effect gives the possibility to overcome fundamental limitations related to the high activation energy of donors in diamond and design high-performance practical single-photon sources. More information can be found on the project web page: https://mipt.ru/en/science/labs/nano/funding_ru/russian-science-foundation-highly-efficient-electrically-driven-single-photon-sources-based-on-color.php
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13. Вишневый А.А., Федянин Д.Ю. Noise reduction in plasmonic amplifiers Applied Physics Express, - (year - 2018).
14. Храмцов И.А., Вишневый А.А., Федянин Д.Ю. Enhancing the brightness of electrically driven single-photon sources using color centers in silicon carbide npj Quantum Information, 4, 15 (year - 2018).
Annotation of the results obtained in 2018
At the first stage of the project, we discovered the effect of superinjection of electrons in homojunction diamond p-i-n diodes, which allows injecting into the i-region of a diode three orders of magnitude more electrons than the doping of the n-type injection layer provides. Since the high activation energy of donors in diamond (~ 0.6 eV) and substantial (~ 10%) compensation of donors by acceptor-type defects limit the electron density to less than 10^11 см^-3, the superinjection effect is of great practical interest. It gives the possibility to significantly improve the characteristics of diamond electronic and optoelectronic devices, including electrically driven single-photon sources. At the second stage of the project, we investigated the dependence of the strength of the superinjection effect on the parameters of the p-i-n diode. We found that the superinjection is also possible in diamond p-n diodes. However, the strength of the effect, i.e., the maximum density of injected electrons, is more than ten times lower. The strength of the superinjection effect increases as the size of the i-region increases from 0 to 30 micrometers. The optimal size was found to be about 10 micrometers since a high density of injected electrons is achieved at low injection currents and bias voltages. We also investigated the possibility to observe and exploit the superinjection effect in silicon carbide homojunction structures. Using a rigorous numerical approach, we show that at room temperature, in 4H-SiC, 3C-SiC and 6H-SiC p-i-n diodes, the density of injected holes can exceed the density of holes in the p-type injection layer by up to 800 times, which allows to overcome the doping problem. Besides the superinjection effect, we have investigated the characteristics of electrically driven single-photon sources based on color centers in diamond p–i–n diodes. We derived an expression for the second-order autocorrelation function and calculated it using the results of the numerical simulations of the diamond single-photon emitting diode (SPED). We found a response time of the SPED based on NV-centers and SiV-centers in diamond and evaluated the influence of self-heating on the emission properties. Finally, we proposed a novel scheme for electrical pumping of color centers in diamond. It is based on a Schottky contact between gold and hydrogen passivated n-type diamond. Despite that Schottky diodes are usually treated as majority carrier devices, we found that an exceptionally high Schottky barrier height gives the possibility to efficiently inject holes from the metal to the n-type diamond. This approach gives the possibility to avoid a complicated procedure of p-i-n structure growth and fabricate electrically driven single-photon sources using only n-type diamond wafers. More information can be found on the project web page: https://mipt.ru/en/science/labs/nano/funding_ru/russian-science-foundation-highly-efficient-electrically-driven-single-photon-sources-based-on-color.php
1. Храмцов И.А., Федянин Д.Ю. Superinjection in single-photon emitting diamond diodes Серия книг International Conference on Numerical Simulation of Optoelectronic Devices, 18TH INTERNATIONAL CONFERENCE ON NUMERICAL SIMULATION OF OPTOELECTRONIC DEVICES (NUSOD 2018), 123-124 (year - 2018).
2. Храмцов И.А., Федянин Д.Ю. Superinjection in diamond homojunction P-I-N diodes Semiconductor Science and Technology, Semicond. Sci. Technol. 34, 03LT03 (year - 2019).
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