Abstract The electron beam absorbed current (EBAC) method identifies the open and/or short points in various semiconductor devices, which can be applied to characterize the current path and local resistance in graphene. In this study, potassium (K)-doped few-layer graphene with inhomogeneous K atoms seemed to be one of the appropriate materials to characterize the current path by EBAC. Nonuniform contrast in the EBAC image due to inhomogeneous local resistances is observed, which is explained by the variation of the Fermi level in the graphene channel from the G-band peak shifts from Raman spectroscopy. The changes in the contrast of the EBAC images are obtained by applying a gate voltage. These changes are attributed to the modulation of the local carrier densities by applying the gate voltage. For comparison, uniform contrast in EBAC images and uniform G-band peak positions of undoped few-layer graphene FETs are confirmed. The obtained results suggest that homogeneous Fermi level leads to uniform current path. EBAC enables us to evaluate the uniformity of local resistance and current through a pass in the graphene channel, which can be applied to other two-dimensional materials, such as transition metal dichalcogenides, graphene oxide and h -BN.
{"title":"Electrical resistivity mapping of potassium-doped few-layer CVD graphene by EBAC measurements","authors":"Yuki Okigawa, Hideaki Nakajima, Toshiya Okazaki, Takatoshi Yamada","doi":"10.1088/1361-6463/ad0aee","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0aee","url":null,"abstract":"Abstract The electron beam absorbed current (EBAC) method identifies the open and/or short points in various semiconductor devices, which can be applied to characterize the current path and local resistance in graphene. In this study, potassium (K)-doped few-layer graphene with inhomogeneous K atoms seemed to be one of the appropriate materials to characterize the current path by EBAC. Nonuniform contrast in the EBAC image due to inhomogeneous local resistances is observed, which is explained by the variation of the Fermi level in the graphene channel from the G-band peak shifts from Raman spectroscopy. The changes in the contrast of the EBAC images are obtained by applying a gate voltage. These changes are attributed to the modulation of the local carrier densities by applying the gate voltage. For comparison, uniform contrast in EBAC images and uniform G-band peak positions of undoped few-layer graphene FETs are confirmed. The obtained results suggest that homogeneous Fermi level leads to uniform current path. EBAC enables us to evaluate the uniformity of local resistance and current through a pass in the graphene channel, which can be applied to other two-dimensional materials, such as transition metal dichalcogenides, graphene oxide and h -BN.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":" 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135340948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract We demonstrate experimentally and numerically the electromagnetic induced transparency (EIT) effect in a strongly coupled planar terahertz metamaterial. The circular shaped four-arcs geometry combined cross resonators ensures that polarization insensitive response of the EIT for the orthogonal polarization incident terahertz. The EIT response can be varied by changing the gap between the arc and cross shaped resonators. The field profiles indicate a strong coupling between the resonators leading to the EIT effect. In order to understand the underlying physical mechanism, we have employed a coupled harmonic oscillator model which suggests increase in coupling when the distance between resonators is reduced. Terahertz time domain spectroscopy of the fabricated samples with same shape and sizes of the simulated structures verify the numerical findings. Our study with symmetric and easy to fabricate planar metasurface can pave the way for design and construction of terahertz photonic components such as optical switches, slow light devices, etc.
{"title":"Electromagnetically induced transparency in a strongly coupled orthogonal polarization insensitive planar terahertz metamaterial","authors":"Lavi Kumar vaswani, Bhagwat Singh Chouhan, Anuraj Panwar, Gagan Kumar","doi":"10.1088/1361-6463/ad0aed","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0aed","url":null,"abstract":"Abstract We demonstrate experimentally and numerically the electromagnetic induced transparency (EIT) effect in a strongly coupled planar terahertz metamaterial. The circular shaped four-arcs geometry combined cross resonators ensures that polarization insensitive response of the EIT for the orthogonal polarization incident terahertz. The EIT response can be varied by changing the gap between the arc and cross shaped resonators. The field profiles indicate a strong coupling between the resonators leading to the EIT effect. In order to understand the underlying physical mechanism, we have employed a coupled harmonic oscillator model which suggests increase in coupling when the distance between resonators is reduced. Terahertz time domain spectroscopy of the fabricated samples with same shape and sizes of the simulated structures verify the numerical findings. Our study with symmetric and easy to fabricate planar metasurface can pave the way for design and construction of terahertz photonic components such as optical switches, slow light devices, etc.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":" 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135340942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.1088/1361-6463/ad0ac1
Xun Hu, Lijing Kong, Pan Yang, Na Gao, Huang Kai, Shuping Li, Junyong Kang, Rong Zhang
Abstract A comparable concentration of carriers injected and transported into the active region, that is, balanced hole and electron injection, significantly affects the optoelectronic performance of AlGaN-based deep ultraviolet light emitting diodes (DUV LEDs). In this study,-we introduce a novel structure characterized by a carrier injection balanced modulation layer, incorporating a polarization-regulating gradient p-AlGaN in a DUV LED. We conducted a systematic examination of its impact on the carrier injection and transport processes.
Theoretical simulations demonstrate the mitigation of abrupt variations in Al content at the interface between EBL/p-AlGaN and p-AlGaN/p-GaN within the valence bands. Consequently, holes are more likely to be injected into the active region rather than accumulating at these interfaces. Meanwhile, due to the reduced barrier height at the top of the valence band, the holes were efficiently transported into the quantum well and confined with comparable and balanced concentrations of electrons by suppressing overflow, thereby promoting the radiative recombination rate. Compared with the conventional DUV LED, the hole concentration and radiative recombination rate of the designed structure in the final quantum well are significantly increased to 179.8% and 232.3%, respectively. The spontaneous emission intensity achieves nearly twice at the same current injection density. Moreover, the efficiency droop is significantly suppressed when operated at a gradually increasing current density. This study presents a promising approach that can serve as a reference for achieving high-efficiency AlGaN-based DUV LEDs.
{"title":"Enhanced performance of AlGaN-based deep-UV LED by incorporating carrier injection balanced modulation layer synergistically with polarization-regulating structures","authors":"Xun Hu, Lijing Kong, Pan Yang, Na Gao, Huang Kai, Shuping Li, Junyong Kang, Rong Zhang","doi":"10.1088/1361-6463/ad0ac1","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0ac1","url":null,"abstract":"Abstract A comparable concentration of carriers injected and transported into the active region, that is, balanced hole and electron injection, significantly affects the optoelectronic performance of AlGaN-based deep ultraviolet light emitting diodes (DUV LEDs). In this study,-we introduce a novel structure characterized by a carrier injection balanced modulation layer, incorporating a polarization-regulating gradient p-AlGaN in a DUV LED. We conducted a systematic examination of its impact on the carrier injection and transport processes.
Theoretical simulations demonstrate the mitigation of abrupt variations in Al content at the interface between EBL/p-AlGaN and p-AlGaN/p-GaN within the valence bands. Consequently, holes are more likely to be injected into the active region rather than accumulating at these interfaces. Meanwhile, due to the reduced barrier height at the top of the valence band, the holes were efficiently transported into the quantum well and confined with comparable and balanced concentrations of electrons by suppressing overflow, thereby promoting the radiative recombination rate. Compared with the conventional DUV LED, the hole concentration and radiative recombination rate of the designed structure in the final quantum well are significantly increased to 179.8% and 232.3%, respectively. The spontaneous emission intensity achieves nearly twice at the same current injection density. Moreover, the efficiency droop is significantly suppressed when operated at a gradually increasing current density. This study presents a promising approach that can serve as a reference for achieving high-efficiency AlGaN-based DUV LEDs.
","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":" 39","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135341410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.1088/1361-6463/ad0ac2
Dingchen Li, Chuan Li, Menghan Xiao, Li Jiawei, Zhiwen Yang, Qixiong Fu, Ming Zhang, Kexun Yu, Yuan Pan
Abstract Water scarcity is a global challenge that hinders human development. In recent years, electrostatic fog collection technology has emerged as a promising technology to alleviate this issue. Although electrostatic fog collectors based on a variety of electrode structures have been developed previously, there has been less research into other factors affecting the efficiency of electrostatic fog collection (e.g. electrical factors, environmental factors, etc.), which has delayed the commercial application of the technology. In this paper, we experimentally investigate the effects of power supply polarity, voltage, airflow direction, airflow velocity, fog concentration and temperature on collection efficiency using a typical wire-mesh electrode fog collector as an example. The results show that both electrical and environmental factors influence the collection efficiency by changing the charge and the electric field force of the droplets. Negative polarity corona and high voltage are more favorable for fog collection. High velocity airflow and high fog concentration increase the amount of water collected due to the ability to bring more droplets into the electric field. However, the collection efficiency is reduced by the weakening of the corona discharge. High temperature accelerates the evaporation of fog droplets, which is not favorable for fog collection. In conclusion, this work will not only contribute to revealing the underlying mechanisms of the electrostatic fog collection but also will guide the development of highly efficient fog collectors.
{"title":"Deconstructing Plasma Fog Collection Technology: An Experimental Study on Factors Impacting Collection Efficiency","authors":"Dingchen Li, Chuan Li, Menghan Xiao, Li Jiawei, Zhiwen Yang, Qixiong Fu, Ming Zhang, Kexun Yu, Yuan Pan","doi":"10.1088/1361-6463/ad0ac2","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0ac2","url":null,"abstract":"Abstract Water scarcity is a global challenge that hinders human development. In recent years, electrostatic fog collection technology has emerged as a promising technology to alleviate this issue. Although electrostatic fog collectors based on a variety of electrode structures have been developed previously, there has been less research into other factors affecting the efficiency of electrostatic fog collection (e.g. electrical factors, environmental factors, etc.), which has delayed the commercial application of the technology. In this paper, we experimentally investigate the effects of power supply polarity, voltage, airflow direction, airflow velocity, fog concentration and temperature on collection efficiency using a typical wire-mesh electrode fog collector as an example. The results show that both electrical and environmental factors influence the collection efficiency by changing the charge and the electric field force of the droplets. Negative polarity corona and high voltage are more favorable for fog collection. High velocity airflow and high fog concentration increase the amount of water collected due to the ability to bring more droplets into the electric field. However, the collection efficiency is reduced by the weakening of the corona discharge. High temperature accelerates the evaporation of fog droplets, which is not favorable for fog collection. In conclusion, this work will not only contribute to revealing the underlying mechanisms of the electrostatic fog collection but also will guide the development of highly efficient fog collectors.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":" 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135341265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-08DOI: 10.1088/1361-6463/ad0ac0
Kazuaki Iguchi, Yuta Nishigawa, Yoriko Suda, Yasushi Nanai, Tsuyoshi Okuno
Abstract In afterglow phosphors, luminescence appears and can be observed with the naked eye for minutes to hours or more, even after photoexcitation ceases. Red afterglow and photostimulated luminescence (PSL) at 650 nm are studied in CaS:Eu2+,Mn2+ phosphors. Infrared light at 980 nm from a laser diode induces the red PSL for 990 s. Two types of trap states are found to be present in the phosphors by using thermoluminescence (TL). Deep trap states are reflected in a TL peak in the temperature region of 520 K, and are related to PSL. Shallow trap states reflected in the other TL peak at 250 K are related to afterglow. The intensity dependence of photoexcitation on PSL shows that carriers are more easily accumulated in the deep trap states than shallow trap states. Experiments of electron paramagnetic resonance are conducted to discuss the possible origins of PSL and the afterglow.
{"title":"Red photostimulated luminescence and afterglow in CaS:Eu<sup>2+,</sup>Mn<sup>2+</sup> phosphors","authors":"Kazuaki Iguchi, Yuta Nishigawa, Yoriko Suda, Yasushi Nanai, Tsuyoshi Okuno","doi":"10.1088/1361-6463/ad0ac0","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0ac0","url":null,"abstract":"Abstract In afterglow phosphors, luminescence appears and can be observed with the naked eye for minutes to hours or more, even after photoexcitation ceases. Red afterglow and photostimulated luminescence (PSL) at 650 nm are studied in CaS:Eu2+,Mn2+ phosphors. Infrared light at 980 nm from a laser diode induces the red PSL for 990 s. Two types of trap states are found to be present in the phosphors by using thermoluminescence (TL). Deep trap states are reflected in a TL peak in the temperature region of 520 K, and are related to PSL. Shallow trap states reflected in the other TL peak at 250 K are related to afterglow. The intensity dependence of photoexcitation on PSL shows that carriers are more easily accumulated in the deep trap states than shallow trap states. Experiments of electron paramagnetic resonance are conducted to discuss the possible origins of PSL and the afterglow.&#xD;","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":" 25","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135341418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-07DOI: 10.1088/1361-6463/ad0a3e
Simon Evertz, Nina Nicolin, Ningyan Cheng, Daniel Primetzhofer, James P. Best, Gerhard Dehm
Abstract Wüstite, Fe 1-x O, is a crucial phase for the transition to CO 2 -free steel manufacturing as well as promising for electrochemical applications such as water splitting and ammonia synthesis. To study the effect of interfaces in these applications, thin-film model systems with defined interfaces are ideal. Previous studies lack a description of the growth mechanism to obtain Fe 1-x O thin films. Here, we investigate the phase formation of metastable Fe 1-x O during reactive magnetron sputtering while systematically varying the O 2 /Ar flow ratio from 1.8 to 7.2% and the pressure-distance product between 3.5 and 7.2 Pa∙cm. If bulk diffusion is minimized, thin films containing 96 vol.% wüstite and 4 vol.% Fe as impurity phase were achieved. Therefore, the formation of the wüstite phase appears to be surface diffusion dominated. To reveal the influence of impurity phases in wüstite on the electrical resistivity, systematic electrical resistivity measurements while cooling in situ were performed for the first time. The electrical resistivity was lower than that of single crystals of the respective iron oxides. This is attributed to the formation of Fe-rich layers at the substrate-film interface, which serve as additional conduction paths.
{"title":"Phase formation and electrical properties of reactively sputtered Fe<sub>1-x</sub>O thin films","authors":"Simon Evertz, Nina Nicolin, Ningyan Cheng, Daniel Primetzhofer, James P. Best, Gerhard Dehm","doi":"10.1088/1361-6463/ad0a3e","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0a3e","url":null,"abstract":"Abstract Wüstite, Fe 1-x O, is a crucial phase for the transition to CO 2 -free steel manufacturing as well as promising for electrochemical applications such as water splitting and ammonia synthesis. To study the effect of interfaces in these applications, thin-film model systems with defined interfaces are ideal. Previous studies lack a description of the growth mechanism to obtain Fe 1-x O thin films. Here, we investigate the phase formation of metastable Fe 1-x O during reactive magnetron sputtering while systematically varying the O 2 /Ar flow ratio from 1.8 to 7.2% and the pressure-distance product between 3.5 and 7.2 Pa∙cm. If bulk diffusion is minimized, thin films containing 96 vol.% wüstite and 4 vol.% Fe as impurity phase were achieved. Therefore, the formation of the wüstite phase appears to be surface diffusion dominated. To reveal the influence of impurity phases in wüstite on the electrical resistivity, systematic electrical resistivity measurements while cooling in situ were performed for the first time. The electrical resistivity was lower than that of single crystals of the respective iron oxides. This is attributed to the formation of Fe-rich layers at the substrate-film interface, which serve as additional conduction paths.&#xD;","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"7 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135480175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-06DOI: 10.1088/1361-6463/ad066d
Shahid Hussain, Xueyu Guan, Ruonan Ji, Shao-Wei Wang
Abstract The use of plasmonic chiral metamaterials for the control of circular polarization has the potential to replace conventional optical equipment for polarization-related applications. The ultra-broadband chiroptic response using plasmonic constituents is delivered by elaborate three-dimensional (3D) helical structures, nevertheless, their implementation is complicated, time-consuming, and poses a significant scaling difficulty at the nano level. Ultra-broadband response from planar constituents is particularly necessary as a means to circumvent the challenges of 3D metamaterials. Here we present a planar plasmonic structure composed of tri-layer anisotropic arrays constituting nanowires and cut-wires to generate dual overlapped chiral bands. Based on this tri-layer approach, we numerically realized ultra-broadband planar plasmonic metamaterials to function in the near- and mid-infrared regions with a bandwidth range of 1.38–3.07 µ m and 4.00–8.10 µ m, and maximum circular dichroism performance of 0.90 and 0.92 respectively. The structures are ultracompact, misalignments tolerant, and can be extended to additional spectral regions through structural engineering. The proposed metamaterial has the potential to be used in the creation of ultra-compact, high-performance devices for a wide variety of uses, such as those in the fields of optical communication, biological diagnosis, high-contrast polarization imaging, high-accuracy polarimetric measurements, and spectroscopy.
{"title":"Ultra-wideband chiroptical response by tri-layer anisotropic plasmonic metamaterial","authors":"Shahid Hussain, Xueyu Guan, Ruonan Ji, Shao-Wei Wang","doi":"10.1088/1361-6463/ad066d","DOIUrl":"https://doi.org/10.1088/1361-6463/ad066d","url":null,"abstract":"Abstract The use of plasmonic chiral metamaterials for the control of circular polarization has the potential to replace conventional optical equipment for polarization-related applications. The ultra-broadband chiroptic response using plasmonic constituents is delivered by elaborate three-dimensional (3D) helical structures, nevertheless, their implementation is complicated, time-consuming, and poses a significant scaling difficulty at the nano level. Ultra-broadband response from planar constituents is particularly necessary as a means to circumvent the challenges of 3D metamaterials. Here we present a planar plasmonic structure composed of tri-layer anisotropic arrays constituting nanowires and cut-wires to generate dual overlapped chiral bands. Based on this tri-layer approach, we numerically realized ultra-broadband planar plasmonic metamaterials to function in the near- and mid-infrared regions with a bandwidth range of 1.38–3.07 µ m and 4.00–8.10 µ m, and maximum circular dichroism performance of 0.90 and 0.92 respectively. The structures are ultracompact, misalignments tolerant, and can be extended to additional spectral regions through structural engineering. The proposed metamaterial has the potential to be used in the creation of ultra-compact, high-performance devices for a wide variety of uses, such as those in the fields of optical communication, biological diagnosis, high-contrast polarization imaging, high-accuracy polarimetric measurements, and spectroscopy.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"105 6","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135584882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract A double network hydrogel based on Poly(vinyl-alcohol) (PVA) cross-linked with Glutaraldehyde (GTA) was recently developed by using self-assembling phenylalanine (Phe) peptide derivative (Fmoc-Phe-Phe-OMe), with the aim to improve the mechanical-elastic properties of PVA-GTA hydrogels. In this study, a characterization of the properties of Xylenol Orange based Fricke gel dosimeters obtained by infusing a Fricke solution into the double network hydrogel was performed. The gel dosimeters were irradiated with 6 MV and 15 MV X-rays produced by a medical linear accelerator and investigated by means optical absorbance measurements. 
The double network hydrogel formulation maintained a satisfactory level of radiological water-equivalence within the investigated radiotherapy range. Fricke gel dosimeters prepared with such network kept the desired properties of independence of the response of the dose rate and energy in the investigated intervals. Furthermore, the addition of self-assembling Phe peptide derivative proved not avoid the motion of radio-inducted ferric ions into the hydrogel, probably maintaining the main characteristics of the standard, no Phe peptide infused, formulation. The time course of formation of the optical response after the irradiation was observed to be similar to what previously measured in traditional PVA-GTA Fricke gel dosimeters, while a decrease of the sensitivity to radiation dose of the order of 30% was found. The extent of the decrease does not seem such as to impair the use of these dosimeters for evaluation of doses typical of radiation therapy applications. 
The overall dosimetric properties, coupled with the mechanical-elastic characteristics of the double network hydrogel, pave the way to the development of phantoms able both to mimic the deformation of organs possibly occurring during radiotherapy treatments and at the same time to assess the 3D dose distribution within such volumes.
{"title":"Dosimetric characterization of double network Fricke hydrogel based on PVA-GTA and phenylalanine peptide derivative","authors":"Salvatore Gallo, Silvia Locarno, Elisa Brambilla, Cristina Lenardi, Emanuele Pignoli, Ivan Veronese","doi":"10.1088/1361-6463/ad0987","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0987","url":null,"abstract":"Abstract A double network hydrogel based on Poly(vinyl-alcohol) (PVA) cross-linked with Glutaraldehyde (GTA) was recently developed by using self-assembling phenylalanine (Phe) peptide derivative (Fmoc-Phe-Phe-OMe), with the aim to improve the mechanical-elastic properties of PVA-GTA hydrogels. In this study, a characterization of the properties of Xylenol Orange based Fricke gel dosimeters obtained by infusing a Fricke solution into the double network hydrogel was performed. The gel dosimeters were irradiated with 6 MV and 15 MV X-rays produced by a medical linear accelerator and investigated by means optical absorbance measurements. &#xD;The double network hydrogel formulation maintained a satisfactory level of radiological water-equivalence within the investigated radiotherapy range. Fricke gel dosimeters prepared with such network kept the desired properties of independence of the response of the dose rate and energy in the investigated intervals. Furthermore, the addition of self-assembling Phe peptide derivative proved not avoid the motion of radio-inducted ferric ions into the hydrogel, probably maintaining the main characteristics of the standard, no Phe peptide infused, formulation. The time course of formation of the optical response after the irradiation was observed to be similar to what previously measured in traditional PVA-GTA Fricke gel dosimeters, while a decrease of the sensitivity to radiation dose of the order of 30% was found. The extent of the decrease does not seem such as to impair the use of these dosimeters for evaluation of doses typical of radiation therapy applications. &#xD;The overall dosimetric properties, coupled with the mechanical-elastic characteristics of the double network hydrogel, pave the way to the development of phantoms able both to mimic the deformation of organs possibly occurring during radiotherapy treatments and at the same time to assess the 3D dose distribution within such volumes.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"105 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135819076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-03DOI: 10.1088/1361-6463/acfcc5
Sumit Kumar, Simran Nehra, Shikha Shrivastava, A. Rathi, Kamlesh Kumar Maurya, Sunil Ojha, Sonu Chhillar, C. S. Yadav, Vipin Chawla, Anjana Dogra
Abstract In search of novel conducting oxide heterointerfaces, we previously uncovered an distinctive quasi two-dimensional electron gas (q-2DEG) type behaviour in non-stoichimetric Ca x Ta y O 3-δ /SrTiO 3 heterostructure. However, the underlying mechanism remained enigmatic. In this study, we delve into the intricate interplay of growth conditions, stoichiometry, and transport properties of these heterostructures. Using (Ca 0.5 TaO 3 ) 2 Target and the pulsed laser deposition technique, we grow the epitaxial thin films while systematically varying growth parameters, inculding laser energy density, oxygen pressures, and post-deposition annealing. Structural analysis unveiled a notable presence of oxygen vacancies in the as-grown films, while annealed samples exhibited an oxygen surplus. Building upon these findings, our comprehensive charge transport measurements revealed that while oxygen vacancies do contribute to conductivity, the polar catastrophe model takes precedence as the primary source of interfacial conductance in these heterostructures. This study provides valueable insights into the behavior of these innovative heterostructures, paving the way for future advancements in the field.
为了寻找新的导电氧化物异质界面，我们之前在非化学测量的Ca x Ta y O 3-δ /SrTiO 3异质结构中发现了一种独特的准二维电子气(q-2DEG)型行为。然而，潜在的机制仍然是个谜。在这项研究中，我们深入研究了这些异质结构的生长条件、化学计量学和输运性质之间复杂的相互作用。利用(Ca 0.5 TaO 3) 2靶和脉冲激光沉积技术，系统地改变生长参数，包括激光能量密度、氧压力和沉积后退火，生长外延薄膜。结构分析揭示了生长薄膜中明显存在氧空位，而退火样品则表现出氧过剩。在这些发现的基础上，我们的综合电荷输运测量显示，虽然氧空位确实有助于电导率，但极性突变模型优先成为这些异质结构中界面电导率的主要来源。这项研究为这些创新异质结构的行为提供了有价值的见解，为该领域的未来发展铺平了道路。
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Pub Date : 2023-11-03DOI: 10.1088/1361-6463/ad098c
Vl A Margulis, E E Muryumin
Abstract A theory is presented for the acoustoelectric (AE) effect in narrow graphene nanoribbons (GNRs) deposited on a piezoelectric substrate when a surface acoustic wave (SAW) is launched onto the surface of the piezoelectric. It is assumed that the electron density in such GNRs can be controlled by applying an external gate voltage, and the acoustic wavelength is much smaller than the mean free path of electrons, so that the quantum mode of interaction of those electrons with the SAW in realized. Using the kinetic theoryapproach, we calculate the AE current flowing through the GNR sample and arising as a result of momentum transfer from coherent SAW phonons to conduction electrons. It is shown that size quantization of the electron energy spectrum in narrow GNRs leads to giant periodic oscillations of the AE current with a change in the gate voltage. AE current surges occur whenever the Fermi level, rising with increasing gate voltage, crosses in turn the bottom of each of the successive size-quantized electron energy subbands. The oscillations predicted are giant in the sense that the maximum values of the current exceed its minimum values by at least an order of magnitude, and they can be observed in narrow GNRs ∼ 10 nm wide even at room temperature.
{"title":"Giant quantum oscillations of acoustoelectric current in narrow graphene nanoribbons","authors":"Vl A Margulis, E E Muryumin","doi":"10.1088/1361-6463/ad098c","DOIUrl":"https://doi.org/10.1088/1361-6463/ad098c","url":null,"abstract":"Abstract A theory is presented for the acoustoelectric (AE) effect in narrow graphene nanoribbons (GNRs) deposited on a piezoelectric substrate when a surface acoustic wave (SAW) is launched onto the surface of the piezoelectric. It is assumed that the electron density in such GNRs can be controlled by applying an external gate voltage, and the acoustic wavelength is much smaller than the mean free path of electrons, so that the quantum mode of interaction of those electrons with the SAW in realized. Using the kinetic theoryapproach, we calculate the AE current flowing through the GNR sample and arising as a result of momentum transfer from coherent SAW phonons to conduction electrons. It is shown that size quantization of the electron energy spectrum in narrow GNRs leads to giant periodic oscillations of the AE current with a change in the gate voltage. AE current surges occur whenever the Fermi level, rising with increasing gate voltage, crosses in turn the bottom of each of the successive size-quantized electron energy subbands. The oscillations predicted are giant in the sense that the maximum values of the current exceed its minimum values by at least an order of magnitude, and they can be observed in narrow GNRs ∼ 10 nm wide even at room temperature.&#xD;","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"102 4‐5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135818972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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