Pub Date : 2024-05-10DOI: 10.35848/1347-4065/ad3f5b
Koki Okuno, Naoki Okada, Kosuke Iwaide, Nobuhiko Ozaki
We investigated the growth of InAs quantum dots (QDs) in a dots-in-a-well (DWELL) from the perspective of the influence of In segregation from the InGaAs layers in the DWELL. Reflection high-energy electron diffraction (RHEED) measurements during the growth of the lower InGaAs layer indicated that In segregation increased with the In composition of the InGaAs layer. The estimated In segregation values were consistent with the decreases in the critical thickness for the QDs growth and the total volume variations of the grown QDs. These results illustrate that the segregated In from the lower InGaAs layer contributes to the QD growth in the DWELL, and their density increases. Furthermore, RHEED measurements during the growth of the upper InGaAs layer indicated the suppression of the deformation of embedded QDs , which could partially contribute to the longer emission wavelength of the QDs in the DWELL.
{"title":"In segregation influence on properties of InAs quantum dots in dots-in-a-well","authors":"Koki Okuno, Naoki Okada, Kosuke Iwaide, Nobuhiko Ozaki","doi":"10.35848/1347-4065/ad3f5b","DOIUrl":"https://doi.org/10.35848/1347-4065/ad3f5b","url":null,"abstract":"We investigated the growth of InAs quantum dots (QDs) in a dots-in-a-well (DWELL) from the perspective of the influence of In segregation from the InGaAs layers in the DWELL. Reflection high-energy electron diffraction (RHEED) measurements during the growth of the lower InGaAs layer indicated that In segregation increased with the In composition of the InGaAs layer. The estimated In segregation values were consistent with the decreases in the critical thickness for the QDs growth and the total volume variations of the grown QDs. These results illustrate that the segregated In from the lower InGaAs layer contributes to the QD growth in the DWELL, and their density increases. Furthermore, RHEED measurements during the growth of the upper InGaAs layer indicated the suppression of the deformation of embedded QDs , which could partially contribute to the longer emission wavelength of the QDs in the DWELL.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"209 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-08DOI: 10.35848/1347-4065/ad3ab9
J. M. Park, M. Okuyama
Polycrystalline BiFeO3 thick films were prepared on Pt/TiO2/SiO2/Si substates by using magnetic field-assisted pulsed laser deposition. Columnar BiFeO3 thick films were successfully obtained with a thickness of 1.8 μm, owing to an oblique incoming flux and high deposition rate by the confinement of the plume under a magnetic field. In the columnar BiFeO3 thick films, a saturated P-E hysteresis loop was obtained at RT, and the remanent polarization (Pr) and coercive field (Ec) were 42 μC cm−2 and 380 kV cm−1, respectively. Also, the piezoelectric response measured by atomic force microscopy showed a butterfly-shaped curve, and the piezoelectric d33 coefficient was about 50 pm V−1.
{"title":"Characterization of columnar BiFeO3 thick films prepared by magnetic field-assisted pulsed laser deposition","authors":"J. M. Park, M. Okuyama","doi":"10.35848/1347-4065/ad3ab9","DOIUrl":"https://doi.org/10.35848/1347-4065/ad3ab9","url":null,"abstract":"Polycrystalline BiFeO<sub>3</sub> thick films were prepared on Pt/TiO<sub>2</sub>/SiO<sub>2</sub>/Si substates by using magnetic field-assisted pulsed laser deposition. Columnar BiFeO<sub>3</sub> thick films were successfully obtained with a thickness of 1.8 <italic toggle=\"yes\">μ</italic>m, owing to an oblique incoming flux and high deposition rate by the confinement of the plume under a magnetic field. In the columnar BiFeO<sub>3</sub> thick films, a saturated <italic toggle=\"yes\">P-E</italic> hysteresis loop was obtained at RT, and the remanent polarization (<italic toggle=\"yes\">P</italic>\u0000<sub>\u0000<italic toggle=\"yes\">r</italic>\u0000</sub>) and coercive field (<italic toggle=\"yes\">E</italic>\u0000<sub>\u0000<italic toggle=\"yes\">c</italic>\u0000</sub>) were 42 <italic toggle=\"yes\">μ</italic>C cm<sup>−2</sup> and 380 kV cm<sup>−1</sup>, respectively. Also, the piezoelectric response measured by atomic force microscopy showed a butterfly-shaped curve, and the piezoelectric <italic toggle=\"yes\">d</italic>\u0000<sub>33</sub> coefficient was about 50 pm V<sup>−1</sup>.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"64 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140930059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-05-01DOI: 10.35848/1347-4065/ad39bd
Kenichi Watanabe, Yuya Oshima, Nobuhiro Shigyo and Yuho Hirata
The quenching effect is a phenomenon in which the scintillation efficiency decreases when energetic particles with high linear energy transfer, such as high-energy ions, deposit energy within the scintillator. From the viewpoint of discriminating between neutrons and gamma rays in the neutron scintillator, evaluating the quenching effect is crucial because the high-energy ions produced by neutron reactions are used to detect neutrons. Using the user-defined subroutine in the Monte Carlo simulation code PHITS, we demonstrated the calculation of the pulse height spectra obtained from Li-containing scintillators, in which the quenching effect is considered based on the Birks’ formula. By comparing the experimental pulse height spectra with simulation results, which consider the experimental broadening, for the neutron peak and Compton edge formed by mono-energetic gamma rays, we determined the quenching coefficient in the Birks’ formula for Li glass, Ce:LiCaAlF6 and Eu:LiCaAlF6 scintillators.
{"title":"Evaluation of quenching characteristics of Li-containing scintillators","authors":"Kenichi Watanabe, Yuya Oshima, Nobuhiro Shigyo and Yuho Hirata","doi":"10.35848/1347-4065/ad39bd","DOIUrl":"https://doi.org/10.35848/1347-4065/ad39bd","url":null,"abstract":"The quenching effect is a phenomenon in which the scintillation efficiency decreases when energetic particles with high linear energy transfer, such as high-energy ions, deposit energy within the scintillator. From the viewpoint of discriminating between neutrons and gamma rays in the neutron scintillator, evaluating the quenching effect is crucial because the high-energy ions produced by neutron reactions are used to detect neutrons. Using the user-defined subroutine in the Monte Carlo simulation code PHITS, we demonstrated the calculation of the pulse height spectra obtained from Li-containing scintillators, in which the quenching effect is considered based on the Birks’ formula. By comparing the experimental pulse height spectra with simulation results, which consider the experimental broadening, for the neutron peak and Compton edge formed by mono-energetic gamma rays, we determined the quenching coefficient in the Birks’ formula for Li glass, Ce:LiCaAlF6 and Eu:LiCaAlF6 scintillators.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"88 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140829366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-30DOI: 10.35848/1347-4065/ad39f6
Noah Austin-Bingamon, Binod D. C., Yoichi Miyahara
The effective quality factor of the cantilever plays a fundamental role in dynamic mode atomic force microscopy. Here we present a technique to modify the quality factor of an atomic force microscopy cantilever within a Fabry–Perot optical interferometer. The experimental setup uses two separate laser sources to detect and excite the oscillation of the cantilever. While the intensity modulation of the excitation laser drives the oscillation of the cantilever, the average intensity can be used to modify the quality factor via optomechanical force without changing the fiber-cantilever cavity length. The technique enables users to optimize the quality factor for different types of measurements without influencing the deflection measurement sensitivity. An unexpected frequency shift was observed and modelled as temperature dependence of the cantilever’s Young’s modulus, which was validated using finite element simulation. The model was used to compensate for the thermal frequency shift. The simulation provided relations between optical power, temperature, and frequency shift.
{"title":"Control of quality factor of atomic force microscopy cantilever by cavity optomechanical effect","authors":"Noah Austin-Bingamon, Binod D. C., Yoichi Miyahara","doi":"10.35848/1347-4065/ad39f6","DOIUrl":"https://doi.org/10.35848/1347-4065/ad39f6","url":null,"abstract":"The effective quality factor of the cantilever plays a fundamental role in dynamic mode atomic force microscopy. Here we present a technique to modify the quality factor of an atomic force microscopy cantilever within a Fabry–Perot optical interferometer. The experimental setup uses two separate laser sources to detect and excite the oscillation of the cantilever. While the intensity modulation of the excitation laser drives the oscillation of the cantilever, the average intensity can be used to modify the quality factor via optomechanical force without changing the fiber-cantilever cavity length. The technique enables users to optimize the quality factor for different types of measurements without influencing the deflection measurement sensitivity. An unexpected frequency shift was observed and modelled as temperature dependence of the cantilever’s Young’s modulus, which was validated using finite element simulation. The model was used to compensate for the thermal frequency shift. The simulation provided relations between optical power, temperature, and frequency shift.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"15 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140829338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-25DOI: 10.35848/1347-4065/ad32e8
Jinwei Zhang, Qianshu Wu, Zhuoran Luo, Miao Zhang and Yang Liu
Carbon doping is a standard blocking-voltage-enhancing technique for commercial silicon substrate-based AlGaN/GaN power switching transistors, although the incorporation of carbon into GaN may deteriorate the dynamic on-state resistance (dy-Ron) properties of the device. Commonly, researchers have believed that the greater the carbon doping, the greater the deterioration in dy-Ron. Surprisingly, in this work, the opposite was observed: the dy-Ron value decreased as the carbon concentration increased, particularly when the density exceeded several 1017 cm−3. This phenomenon is explained by the effect of electric field-induced band-to-band electron tunneling into the two-dimensional electron gas (2DEG) conduction channel, originating from the ionization of acceptor-like nitrogen site carbon atoms (CN) in the device off-state with large drain bias. Simulation data indicated that negatively ionized CN may generate a much larger electric field in samples with higher carbon doping, which may induce a narrower 2DEG back energy band barrier that increases the possibility of electron band-to-band tunneling.
{"title":"Alleviation of the on-state dynamic conductance decline in a GaN high electron mobility transistor with heavy carbon doping","authors":"Jinwei Zhang, Qianshu Wu, Zhuoran Luo, Miao Zhang and Yang Liu","doi":"10.35848/1347-4065/ad32e8","DOIUrl":"https://doi.org/10.35848/1347-4065/ad32e8","url":null,"abstract":"Carbon doping is a standard blocking-voltage-enhancing technique for commercial silicon substrate-based AlGaN/GaN power switching transistors, although the incorporation of carbon into GaN may deteriorate the dynamic on-state resistance (dy-Ron) properties of the device. Commonly, researchers have believed that the greater the carbon doping, the greater the deterioration in dy-Ron. Surprisingly, in this work, the opposite was observed: the dy-Ron value decreased as the carbon concentration increased, particularly when the density exceeded several 1017 cm−3. This phenomenon is explained by the effect of electric field-induced band-to-band electron tunneling into the two-dimensional electron gas (2DEG) conduction channel, originating from the ionization of acceptor-like nitrogen site carbon atoms (CN) in the device off-state with large drain bias. Simulation data indicated that negatively ionized CN may generate a much larger electric field in samples with higher carbon doping, which may induce a narrower 2DEG back energy band barrier that increases the possibility of electron band-to-band tunneling.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"124 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140804386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-24DOI: 10.35848/1347-4065/ad39bc
Yao Zhao, Weiwei Duan and Lili Yuan
Based on the principle that the polarization state of light propagating in a single-mode fiber changes with external strains, an optical fiber sensor system based on machine learning and polarization for multi-point strain measurement is proposed. To address the influence of the front sensor on the rear sensor and to minimize interference from unrelated inputs, we have employed a data processing method that constructs an individual neural network model for each sensor. This approach uses the polarization state of the reflected light of the sensors as the neural networks’ input and the sensors’ rotation angles as the output, training the designed neural networks for learning. The trained neural networks produce predicted outputs that demonstrate high consistency with the experimental data, achieving an average prediction accuracy of 99% on test data. These results validate the effectiveness of our sensor system and data processing method.
{"title":"Development of optical fiber strain sensor system based on machine learning and polarization","authors":"Yao Zhao, Weiwei Duan and Lili Yuan","doi":"10.35848/1347-4065/ad39bc","DOIUrl":"https://doi.org/10.35848/1347-4065/ad39bc","url":null,"abstract":"Based on the principle that the polarization state of light propagating in a single-mode fiber changes with external strains, an optical fiber sensor system based on machine learning and polarization for multi-point strain measurement is proposed. To address the influence of the front sensor on the rear sensor and to minimize interference from unrelated inputs, we have employed a data processing method that constructs an individual neural network model for each sensor. This approach uses the polarization state of the reflected light of the sensors as the neural networks’ input and the sensors’ rotation angles as the output, training the designed neural networks for learning. The trained neural networks produce predicted outputs that demonstrate high consistency with the experimental data, achieving an average prediction accuracy of 99% on test data. These results validate the effectiveness of our sensor system and data processing method.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"47 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140804394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-04-21DOI: 10.35848/1347-4065/ad37c1
Hideaki Numata, Noriyuki Iguchi, Masamitsu Tanaka, Koichiro Okamoto, Sadahiko Miura, Ken Uchida, Hiroki Ishikuro, Toshitsugu Sakamoto and Munehiro Tada
A 100 nm wide superconducting niobium (Nb) interconnect was fabricated by a 300 mm wafer process for Cryo-CMOS and superconducting digital logic applications. A low pressure and long throw sputtering was adopted for the Nb deposition, resulting in good superconductivity of the 50 nm thick Nb film with a critical temperature (Tc) of 8.3 K. The interconnects had a titanium nitride (TiN)/Nb stack structure, and a double-layer hard mask was used for the dry etching process. The exposed area of Nb film was minimized to decrease the effects of plasma damage during fabrication and atmosphere. The developed 100 nm wide and 50 nm thick Nb interconnect showed good superconductivity with a Tc of 7.8 K and a critical current of 3.2 mA at 4.2 K. These results are promising for Cryo-CMOS and superconducting digital logic applications in the 4 K stage.
{"title":"Superconducting Nb interconnects for Cryo-CMOS and superconducting digital logic applications","authors":"Hideaki Numata, Noriyuki Iguchi, Masamitsu Tanaka, Koichiro Okamoto, Sadahiko Miura, Ken Uchida, Hiroki Ishikuro, Toshitsugu Sakamoto and Munehiro Tada","doi":"10.35848/1347-4065/ad37c1","DOIUrl":"https://doi.org/10.35848/1347-4065/ad37c1","url":null,"abstract":"A 100 nm wide superconducting niobium (Nb) interconnect was fabricated by a 300 mm wafer process for Cryo-CMOS and superconducting digital logic applications. A low pressure and long throw sputtering was adopted for the Nb deposition, resulting in good superconductivity of the 50 nm thick Nb film with a critical temperature (Tc) of 8.3 K. The interconnects had a titanium nitride (TiN)/Nb stack structure, and a double-layer hard mask was used for the dry etching process. The exposed area of Nb film was minimized to decrease the effects of plasma damage during fabrication and atmosphere. The developed 100 nm wide and 50 nm thick Nb interconnect showed good superconductivity with a Tc of 7.8 K and a critical current of 3.2 mA at 4.2 K. These results are promising for Cryo-CMOS and superconducting digital logic applications in the 4 K stage.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"87 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140804393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The availability of photoelectrical characterizations of heavily Al-doped p-SiC Schottky contacts was clarified. We conducted a systematic study of four samples with different Al doping concentrations from 1 × 1018 to 5 × 1019 cm−3. Although the current–voltage (I–V) characteristics had lost rectification, reasonable Schottky barrier height (qϕB) values were obtained up to 1 × 1019 cm−3 by capacitance voltage, photo response, and scanning internal photoemission microscopy (SIPM) measurements. In the two-dimensional characterization by SIPM, large photocurrent spots corresponding with low qϕB were observed in an average density of 103 to 104 cm−2. However, except for these spots, a high uniformity of about 2 meV standard deviation was obtained for qϕB over the entire observed electrodes. These results indicate that SIPM is able to characterize the inhomogeneity of heavily doped p-SiC contacts with very leaky I–V characteristics.
{"title":"Photoelectrical characterization of heavily doped p-SiC Schottky contacts","authors":"Hiroki Imabayashi, Hitose Sawazaki, Haruto Yoshimura, Masashi Kato, Kenji Shiojima","doi":"10.35848/1347-4065/ad32e0","DOIUrl":"https://doi.org/10.35848/1347-4065/ad32e0","url":null,"abstract":"The availability of photoelectrical characterizations of heavily Al-doped p-SiC Schottky contacts was clarified. We conducted a systematic study of four samples with different Al doping concentrations from 1 × 10<sup>18</sup> to 5 × 10<sup>19</sup> cm<sup>−3</sup>. Although the current–voltage (<italic toggle=\"yes\">I–V</italic>) characteristics had lost rectification, reasonable Schottky barrier height (<italic toggle=\"yes\">qϕ</italic>\u0000<sub>B</sub>) values were obtained up to 1 × 10<sup>19</sup> cm<sup>−3</sup> by capacitance voltage, photo response, and scanning internal photoemission microscopy (SIPM) measurements. In the two-dimensional characterization by SIPM, large photocurrent spots corresponding with low <italic toggle=\"yes\">qϕ</italic>\u0000<sub>B</sub> were observed in an average density of 10<sup>3</sup> to 10<sup>4</sup> cm<sup>−2</sup>. However, except for these spots, a high uniformity of about 2 meV standard deviation was obtained for <italic toggle=\"yes\">qϕ</italic>\u0000<sub>B</sub> over the entire observed electrodes. These results indicate that SIPM is able to characterize the inhomogeneity of heavily doped p-SiC contacts with very leaky <italic toggle=\"yes\">I–V</italic> characteristics.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"54 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140804434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Electrically conductive Nb-doped anatase TiO2 (Ti1−xNbxO2: TNO) films can be fabricated through mist CVD using aqueous precursor solutions of water-soluble oxo-peroxo-glycolato titanium complex and ammonium niobium oxalate. Post-deposition annealing in vacuum crystallizes the as-deposited amorphous films into a conductive anatase phase, leading to the fabrication of conductive TNO films. Notably, the addition of H2O2 to the precursor solutions enhances both the crystallinity and conductivity of the annealed TNO films. A Ti0.77N0.23O2 film, annealed at 700 °C, exhibits a resistivity of 2.0 × 10−2 Ω cm at ambient temperature. In general, the solution-based fabrication of TiO2 films relies on organic solvents, which are sometimes toxic and explosive. Here, we demonstrate for the first time that conductive TNO films can be prepared from less toxic and nonflammable aqueous solutions. These findings mark a significant advancement towards a more environmentally compatible process for fabricating TNO films with sufficient conductivity.
{"title":"Fabrication of conductive Nb-doped anatase TiO2 thin films by mist chemical vapor deposition using aqueous solutions of water-soluble Ti and Nb compounds","authors":"Rento Naito, Megumi Ariga, Kaede Makiuchi, Ayaka Nakamura, Tomohito Sudare, Ryo Nakayama, Ryota Shimizu, Kentaro Kaneko, Yasushi Sato, Taro Hitosugi, Naoomi Yamada","doi":"10.35848/1347-4065/ad31d6","DOIUrl":"https://doi.org/10.35848/1347-4065/ad31d6","url":null,"abstract":"Electrically conductive Nb-doped anatase TiO<sub>2</sub> (Ti<sub>1−<italic toggle=\"yes\">x</italic>\u0000</sub>Nb<sub>\u0000<italic toggle=\"yes\">x</italic>\u0000</sub>O<sub>2</sub>: TNO) films can be fabricated through mist CVD using aqueous precursor solutions of water-soluble oxo-peroxo-glycolato titanium complex and ammonium niobium oxalate. Post-deposition annealing in vacuum crystallizes the as-deposited amorphous films into a conductive anatase phase, leading to the fabrication of conductive TNO films. Notably, the addition of H<sub>2</sub>O<sub>2</sub> to the precursor solutions enhances both the crystallinity and conductivity of the annealed TNO films. A Ti<sub>0.77</sub>N<sub>0.23</sub>O<sub>2</sub> film, annealed at 700 °C, exhibits a resistivity of 2.0 × 10<sup>−2 </sup>Ω cm at ambient temperature. In general, the solution-based fabrication of TiO<sub>2</sub> films relies on organic solvents, which are sometimes toxic and explosive. Here, we demonstrate for the first time that conductive TNO films can be prepared from less toxic and nonflammable aqueous solutions. These findings mark a significant advancement towards a more environmentally compatible process for fabricating TNO films with sufficient conductivity.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"26 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140617299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The bowl-shaped molecules of the nanocarbon material called sumanene have structural flexibility (bowl inversion). In the case of the sumanene molecule used as an intercalant between graphene layers, it has been predicted that holes and electrons are unevenly distributed according to the bowl inversion. Using the property of sumanene molecules, we expected that resistive switching for the nonvolatile memory applications could be achieved by the sumanene-inserted bilayer graphene. In this study, metal–insulator–metal devices with sumanene-inserted bilayer graphene are fabricated. As a result, it is observed that the resistance of the sumanene-inserted bilayer graphene changes by applying voltage, demonstrating resistive switching characteristics. This result implies the possibility of realizing a novel ultra-thin resistive memory device using nanocarbon technologies.
{"title":"Resistive switching memory using buckybowl sumanene-inserted bilayer graphene","authors":"Eito Ashihara, Ryoichi Kawai, Ryousuke Ishikawa, Yuichiro Mitani","doi":"10.35848/1347-4065/ad2fe2","DOIUrl":"https://doi.org/10.35848/1347-4065/ad2fe2","url":null,"abstract":"The bowl-shaped molecules of the nanocarbon material called sumanene have structural flexibility (bowl inversion). In the case of the sumanene molecule used as an intercalant between graphene layers, it has been predicted that holes and electrons are unevenly distributed according to the bowl inversion. Using the property of sumanene molecules, we expected that resistive switching for the nonvolatile memory applications could be achieved by the sumanene-inserted bilayer graphene. In this study, metal–insulator–metal devices with sumanene-inserted bilayer graphene are fabricated. As a result, it is observed that the resistance of the sumanene-inserted bilayer graphene changes by applying voltage, demonstrating resistive switching characteristics. This result implies the possibility of realizing a novel ultra-thin resistive memory device using nanocarbon technologies.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"18 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140617381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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