Optoelectronics and Photonics
A.H. Mehrfar; A. Eslami Majd
Abstract
Background and Objectives: The use of two-dimensional materials in the photodetector fabrication has received much attention in recent years. Graphene is a two-dimensional material that has been extensively researched to make photodetectors. The responsivity of graphene photodetectors was limited by ...
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Background and Objectives: The use of two-dimensional materials in the photodetector fabrication has received much attention in recent years. Graphene is a two-dimensional material that has been extensively researched to make photodetectors. The responsivity of graphene photodetectors was limited by the low optical absorption in graphene (~2.3% for single layer graphene). Therefore, graphene along with other materials has been used to fabricate a photodetector with the desired properties. The graphene is used for the improvement of the silicide platinum photodetector.Methods: The platinum silicide photodetector with graphene has been experimentally fabricated and characterized, and all steps of the device fabrication and the characterization are completely provided in addition to required equations for device analysis is completely provided. A graphene layer is transferred on the platinum silicide layer, and the graphene layer creates the photoconductor gain in the platinum silicide photodetector. Results: In the proposed device, near-infrared light is detected in the platinum silicide, and by placing a layer of graphene on the platinum silicide, the optical current and responsivity increase compared to the platinum silicide photodetector without graphene. Experimental results show that the optical current, external quantum efficiency, and responsivity increase in the platinum silicide photodetector with graphene. The graphene not only functions as the charge transport channel, but also works as a photoconductor.Conclusion: The optical current and responsivity are increased by the platinum silicide photodetector with graphene. In our photodetector, the highest responsivity is 120 mA/W in the 1310 nm wavelength, and the optical current is 100 nA at the applied voltage of 8 V. Our photodetector has optical current, responsivity, and external quantum efficiency twice as much as platinum silicide photodetector. Experimental results show the good performance of graphene with platinum silicide photodetector.
Optoelectronics and Photonics
F. Parandin; M. Malmir
Abstract
Background and Objectives: Recently, photonic crystals have been considered as the basic structures for the realization of various optical devices for high speed optical communication.Methods: In this research, two dimensional photonic crystals are used for designing all optical logic gates. A photonic ...
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Background and Objectives: Recently, photonic crystals have been considered as the basic structures for the realization of various optical devices for high speed optical communication.Methods: In this research, two dimensional photonic crystals are used for designing all optical logic gates. A photonic crystal structure with a triangular lattice is proposed for making NAND, XNOR, and OR optical logic gates. Using the structure as the intended logic gate is possible without the need to change the structure through the use of the phase difference at the inputs. Line and point defects have been used to propagate light from inputs to output. The logical values "0" and "1", are defined based on the amount of transferred optical power to the output.Results: The simple structure and the use of line and point defects, instead of ring resonators, reduce the complexity of the design and its use in optical logic integrated circuits. Another advantage of proposed structure, in comparison to the previous structures is the reduction in delay time that increases its speed. The maximum delay time of the proposed optical NAND, XNOR, and OR gates is about 0.1ps.Conclusion: In this study, one structure is suggested for realizing NAND, XNOR, and OR logic gates. This structure has a small size and low delay time, and is suitable for use in optical integrated circuits.
Optoelectronics and Photonics
M. Shaveisi; A. Rezaei
Abstract
Background and Objectives: This study presents the importance of reversible logic in designing of high performance and low power consumption digital circuits. In our research, the various forms of sequential reversible circuits such as D, T, SR and JK flip-flops are investigated based on carbon nanotube ...
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Background and Objectives: This study presents the importance of reversible logic in designing of high performance and low power consumption digital circuits. In our research, the various forms of sequential reversible circuits such as D, T, SR and JK flip-flops are investigated based on carbon nanotube field-effect transistors. Methods: By simultaneous using of the reversible logic gates and carbon nanotube transistors in implementation of various flip-flops and introducing suitable transistor circuits of conventional reversible gates, all reversible flip-flops are simulated in two voltages, 0.3 and 0.5 Volt. The Hspice_H-2013.03-SP2 software is used to simulate these circuits using the 32nm CNTFET technology (the standard Stanford spice model). Results: The simulation results indicate a significant reduction in the average power consumption of D, T, SR and JK flip-flops, respectively about 99.98%, 82.79%, 60.46%, and 81.53%. Conclusion: Our results show that the proposed structures have achieved a high performance in terms of average power consumption and PDP.======================================================================================================Copyrights©2018 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.======================================================================================================
