Figure | Working principle of the optically induced static electric field in a single metal-semiconductor nanoantenna for the second harmonic generation.
Newswise — In solid-state electronics the control of different processes by electric field is widely utilized for industrial on-chip fundamental elements such as field-effect transistors, capacitors, memory and logic. The technological progress of modern devices tends to the miniaturization and transition from operations with electrical signals to optical ones. In turn electric field optically created, probed and controlled in a main nanophotonic building block - single resonant nanoantenna, when implemented, open up the way to the world of compact devices based on electrically-optically manipulated subwavelength elements, such as future nanophotonic processors and neuromorphic devices.
In a new paper published in Light Science & Application, a team of scientists, led by Assistant Professor Dmitry Zuev from Faculty of Physics, ITMO University, Russia, and co-workers have demonstrated a single resonant metal-high refractive index semiconductor nanostructure (MSN) with the static electric field, which is optically generated and built inside this system. To produce direct metal-semiconductor contact in the nanoantenna, they propose combination of lithography and nanomehanical manipulation of the metal component of the MSN through fs-laser irradiation. The Schottky barrier created by the contact establishes a static electric field owing to the charge separation of optically generated charge carriers in the nanoantenna. This field interacts with the third order susceptibility of the MSN semiconductor component, which is probed by the second harmonic generation (SHG) signal. They experimentally revealed that presence of the electric field provides increase of the SHG signal intensity on a time scale of seconds as well as non-quadratic dependence of the SHG signal on the excitation intensity. Such electric field-mediated nonlinear effect is theoretically studied taking into account the metal work function and surface defect density in the MSN in the framework of the drift-diffusion model.
In the MSN the presence of a static electric field created by photogenerated charge carriers provides 2 orders of magnitude in the SHG signal difference, which is achieved by the variation of the excitation intensity. Such SHG output with a high modulation depth paves the way for ultrafast logical operation in a single nanoantenna.
These scientists summarize the principle of creation of optically generated static electric field inside a single nanoantenna:
“The material choice and fabrication approaches play an important role as in future it can help to integrate proposed design in real devices. Moreover, one need: (1) to create the metal-semiconductor interface providing the absorbed energy localization directly at the metal-semiconductor interface; (2) to choose appropriate excitation regime below the damage threshold; and (3) to monitor the field presence, e.g. through some optical processes like the SHG effect”
“The numerically estimated maximum value of optically generated static electric field in the MSN achieves 108 V/m, which is a quite large value. Therefore, we suppose all possible functionalities and applications of such built-in electrical field are even not fully discovered now” they added.
“The demonstrated effects are the first step towards nontrivial designs of optical metasurfaces with expanded functionalities, where electrical field can be created in its separate units by selective irradiation by fs-laser pulses without the need of applying a voltage through electrodes. Our findings could open a way for the creation of the all optical transistor on-chip and help to escape from the time-response-limited optoelectronic technologies of the top-gate type” the scientists forecast.
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References
DOI
Original Source URL
https://doi.org/10.1038/s41377-023-01262-8
Funding information
This research received funding from the Russian Science Foundation (Project 22-72-10035) and Priority 2030 Federal Academic Leadership Program.
About Light: Science & Applications
The Light: Science & Applications will primarily publish new research results in cutting-edge and emerging topics in optics and photonics, as well as covering traditional topics in optical engineering. The journal will publish original articles and reviews that are of high quality, high interest and far-reaching consequence.
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