Article
Engineering, Electrical & Electronic
Dan Zhang, Chaochao Fu, Jing Xu, Chao Zhao, Jianfeng Gao, Yaodong Liu, Menghua Li, Junfeng Li, Wenwu Wang, Dapeng Chen, Tianchun Ye, Dongping Wu, Jun Luo
Summary: This paper discusses the method of using dopant segregation technique to adjust the Schottky barrier heights of NiSi/Si diodes, and presents a technique to distinguish different types of diodes.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Physical
Shuo Li, Qiang Wu, Haokun Ding, Songsong Wu, Xinwei Cai, Rui Wang, Jun Xiong, Guangyang Lin, Wei Huang, Songyan Chen, Cheng Li
Summary: In this study, a p-WSe2/n-Ge vdW heterojunction phototransistor with a Schottky barrier collector on n-Ge for broadband photodetection is reported. The phototransistor exhibits high responsivities, photocurrent gain, and fast response time, making it suitable for high-performance broadband photodetection.
Article
Materials Science, Multidisciplinary
Yota Uehigashi, Shinya Ohmagari, Hitoshi Umezawa, Hideaki Yamada, Jianbo Liang, Naoteru Shigekawa
Summary: p+-Si/p-diamond heterojunction diodes fabricated using surface-activated bonding showed improved electrical properties after post-bonding annealing at temperatures up to 873 K, with better thermal stability compared to Cu/diamond Schottky diodes. The estimated barrier height at Si/diamond bonding interfaces after annealing at 873 K is close to the assumed value when no offset is formed at the vacuum level across the interfaces.
DIAMOND AND RELATED MATERIALS
(2021)
Article
Engineering, Electrical & Electronic
Ishpal Rawal, Vipin Kumar, Vinod Kumar, Prikshit Gautam, Vijay Kumar Sharma
Summary: In this study, p-n hetero-junction devices of p-Zn1-xSbxO/n-Si- were fabricated using radio-frequency sputtering technique and analyzed for morphological and structural modifications. The AFM studies revealed the growth of agglomerated nanoparticles on the film surfaces, while XRD studies showed significant changes in crystal structure and properties with antimony incorporation.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Esra Yukselturk, Ozge Surucu, Makbule Terlemezoglu, Mehmet Parlak, Semsettin Altindal
Summary: The study investigated the I-V characteristics of the fabricated In/In2S3/p-Si photodiode under different illumination intensities, observed two linear regions in the forward-bias ln(I)-V plots, and found that the ideality factor of the diode increased with increasing illumination intensity while the barrier height decreased. The photodiode's photoresponse, photoresponsivity, and specific detectivity were calculated as a function of the illumination.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2021)
Article
Engineering, Mechanical
Mehmet Yilmaz, Hatice Kacus, Maria Luisa Grilli, Sakir Aydogan
Summary: Non-stoichiometric NiO films were fabricated using radio frequency sputtering, and their crystal structure and topographical features were evaluated. The films exhibited cubic polycrystalline nature with microstructural properties varying depending on film thickness. Electrical performance of the films, correlated with their structural properties, showed rectifying properties that improved with increasing film thickness.
JOURNAL OF SANDWICH STRUCTURES & MATERIALS
(2021)
Article
Chemistry, Physical
S. Bhuvaneswari, M. Seetha, J. Chandrasekaran, R. Marnadu, Yoshitake Masuda, Omar M. Aldossary, Mohd Ubaidullah
Summary: Octahedral novel indium tin oxide (ITO) films were fabricated on glass substrates using spray pyrolysis technique with different tin doping concentrations. XRD, surface morphology analysis, XPS inspection, and optical properties studies showed the proper tin doping in indium oxide crystal lattice, improved conductivity, and changes in bandgap.
SURFACES AND INTERFACES
(2021)
Article
Energy & Fuels
Sho Aonuki, Yudai Yamashita, Gianluca Limodio, Shunsuke Narita, Kaori Takayanagi, Ai Iwai, Kaoru Toko, Miro Zeman, Olindo Isabella, Takashi Suemasu
Summary: In this study, n-BaSi2 films were formed on p-Si substrates using ion implantation technique, and the solar-cell functionality of n-BaSi2/p-Si heterojunction was demonstrated under AM1.5 illumination. The results showed that the ion implantation damage could be recovered by postannealing, leading to high internal quantum efficiency.
PROGRESS IN PHOTOVOLTAICS
(2022)
Article
Engineering, Electrical & Electronic
Yance Chen, Xiaoxue Cao, Suhao Wang, Lixiang Liu, Jianhang Lv, Xinyu Liu, Srikrishna Chanakya Bodepudi, Ying Shen, Haiyan Sun, Li Peng, Wenzhang Fang, Jizhou Song, Yang Xu
Summary: In this study, a p-type silicon/graphene/n-type silicon heterojunction was used to fabricate a near-infrared photodetector, and dual built-in electric fields were established in the same direction to enhance electron-hole separation. The resulting device showed higher responsivities and external quantum efficiency compared to the single-junction heterojunction device.
IEEE TRANSACTIONS ON NANOTECHNOLOGY
(2022)
Article
Chemistry, Physical
Milad Sabzehparvar, Fatemeh Kiani, Nooshin Salman Tabrizi
Summary: This study presents a magnetically-recyclable TiO2-NiO-Ag p-n/Schottky heterojunction photocatalyst with enhanced photocatalytic activity, showcasing its potential for practical application in environmental remediation and other photocatalytic applications.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Engineering, Electrical & Electronic
A. Buyukbas Ulusan, A. Tataroglu, S. Altindal, Y. Azizian-Kalandaragh
Summary: The Au/(CoFe2O4-PVP)/n-Si (MPS) diode exhibits good photoresponse characteristics, showing a strong response to illumination with a decrease in parameters such as phi(B0), n, R-s, and I-0 as illumination intensity increases. The double-logarithmic plot of I-ph-P has a slope of 1.27, indicating a lower density of unoccupied trap levels, and the photo-to-dark current ratio confirms the photosensitivity of the diode. The fabricated MPS diode can be used for photovoltaic applications.
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
(2021)
Article
Chemistry, Multidisciplinary
Ruiheng Chang, Qiao Chen, Wang Shen, Youwei Zhang, Butian Zhang, Shun Wang
Summary: Controllable switching from a Schottky junction to a p-n junction in a MoS2 device is achieved using an ionic liquid-gated technique. The formation of the junctions is revealed by spatially resolved photocurrent mappings. The switching behavior is correlated with the evolution of the energy band, as confirmed by finite element simulation.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Dong Hun Lee, Honghwi Park, Michael Clevenger, Hyeonghun Kim, Chung Soo Kim, Mingyuan Liu, Giyong Kim, Han Wook Song, Kwangsoo No, Sung Yeol Kim, Dong-Kyun Ko, Anne Lucietto, Hongsik Park, Sunghwan Lee
Summary: This study demonstrates a simple processing route to fabricate oxide-based p-n heterojunctions with high rectification performance. By selecting appropriate materials and post-processing methods, high on/off rectification behavior, low saturation current, and small turn-on voltage were achieved in the heterojunctions.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Physics, Applied
Yota Uehigashi, Shinya Ohmagari, Hitoshi Umezawa, Hideaki Yamada, Jianbo Liang, Naoteru Shigekawa
Summary: In this study, we evaluated the current-voltage (I-V) and temperature-dependent I-V characteristics of p(+)-Si/p-diamond heterojunction diodes (HDs) fabricated using surface-activated bonding and compared their characteristics with those of Al/p-diamond Schottky barrier diodes (SBDs) fabricated on the same diamond substrate. We found that the characteristics of HDs were improved by annealing, with decreased ideality factor, reverse-bias current, and enhanced on/off ratio, while the characteristics of SBDs showed different responses to annealing. The barrier height at the Si/diamond bonding interfaces decreased after annealing, indicating a decrease in the density of interface states.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Physical
Avishek Banik, John Z. Tubbesing, Bin Luo, Xiaoting Zhang, Jay A. Switzer
Summary: The development of future optoelectronic materials relies on the high-performance p-type materials with optical transparency. Epitaxial growth of gamma-CuI on single crystalline Si(111) using a room-temperature electrochemical method demonstrates high in-plane and out-of-plane order. The deposition mechanism involves nucleating CuI seed crystals on n-Si(111) and simultaneous oxidation of Si to form SiOx, resulting in the lateral overgrowth of CuI seeds into a continuous film.
CHEMISTRY OF MATERIALS
(2021)
Article
Physics, Applied
Hayato Hasebe, Kazuki Kido, Haruki Takenaka, Masami Mesuda, Kaoru Toko, Dmitri B. B. Migas, Takashi Suemasu
Summary: BaSi2 is an important material for thin-film solar cell applications and the control of conductivity through impurity doping is crucial. B-doped p-BaSi2 films were successfully fabricated by molecular beam epitaxy and vacuum evaporation. In this study, B-doped BaSi2 films were prepared on Si substrates by co-sputtering BaSi2, Ba, and B-doped Si targets at 600 degrees C, followed by post-annealing at 900 degrees C or 1000 degrees C in an Ar atmosphere. Surprisingly, as-grown and 900 degrees C annealed samples exhibited n-type conductivity, while the 1000 degrees C annealed sample showed p-type conductivity. The possibility of n-type conductivity in B-doped BaSi2 was discussed based on first-principles calculations considering the presence of oxygen atoms.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Sho Aonuki, Shunsuke Narita, Kaori Takayanagi, Ai Iwai, Yudai Yamashita, Kaoru Toko, Takashi Suemasu
Summary: Boron-ion-implanted p-BaSi2 films were successfully formed by implanting B atoms into BaSi2 epitaxial films grown by molecular beam epitaxy. Raman spectroscopy revealed that the ion-implantation damage in the implanted BaSi2 films could be recovered by post-annealing at temperatures of 600 degrees C or higher for 64 min. The B-ion-implanted p-BaSi2 films showed a hole concentration of 3.1 x 10(18) cm(-3) at room temperature, making them suitable as a hole transport layer. Rectifying current-voltage characteristics were observed in B-ion-implanted p-BaSi2/n-Si heterojunction solar cells under AM1.5 G illumination, with an internal quantum efficiency of 72% at a wavelength of 900 nm. The conversion efficiency of these solar cells was 2.2%. These findings provide new ways to fabricate BaSi2 solar cells.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Ivan I. Khaliava, Alexander L. Khamets, Igor V. Safronov, Andrew B. Filonov, Takashi Suemasu, Dmitri B. Migas
Summary: We used nonequilibrium molecular dynamics to study the effect of morphology on the phonon thermal conductivity of Si/Ge superlattice nanowires with different orientations. The 112-oriented nanowires showed the lowest thermal conductivity due to their unique structure featuring effective phonon-surface and phonon-interface scattering. Comparison with other types of nanowires revealed that the superlattice morphology is the most efficient in reducing thermal conductivity.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Yuguang Cao, Jean-Marie Mouesca, Serge Gambarelli, Takashi Suemasu
Summary: Barium disilicide (BaSi2) is a promising material for thin-film solar cells. In this study, boron was used as a p-type impurity in BaSi2 and its impact on the electrical and optical properties of solar cells was investigated. The results show that interstitial boron defects have lower formation energy compared to boron in Si vacancy sites. Additionally, the hyperfine coupling constants of Ba-137 with different boron defects suggest that they can be identified using electron paramagnetic resonance.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Rui Du, Sho Aonuki, Hayato Hasebe, Kazuki Kido, Haruki Takenaka, Kaoru Toko, Masami Mesuda, Takashi Suemasu
Summary: Sputter-deposited polycrystalline BaSi2 films capped with a 5 nm thick a-SiC layer exhibited high photoresponsivity, indicating that the a-SiC layer acts as a capping layer to prevent surface oxidation of BaSi2. The a-SiC layer is considered as an electron transport layer (ETL) in the BaSi2 light absorber layer/a-SiC interlayer/TiN contact structure, based on the measured absorption edge, electron affinity, and work function of the respective layers. Using a 10 nm thick p(+)-BaSi2 layer as a hole transport layer, the BaSi2/a-SiC layered structure significantly affects the performance of a BaSi2-pn homojunction solar cell, achieving an efficiency of 22% for a 500 nm thick BaSi2 light absorber layer, as predicted by a one-dimensional device simulator (AFORS-HET v2.5).
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Takumi Horiuchi, Taro Komori, Tomohiro Yasuda, Taku Hirose, Kaoru Toko, Kenta Amemiya, Takashi Suemasu
Summary: In this study, we investigate the effect of Au doping on the magnetic structure of Mn4N films, and find a composition ratio-dependent sign reversal of the anomalous Hall effect at room temperature. X-ray magnetic circular dichroism measurement reveals a reversal of the magnetic moment of face-centered Mn atoms between x=0.1 and 0.2, becoming parallel to that of corner-site Mn atoms for x=0.2 and 0.3. This implies a ferrimagnetic-ferromagnetic phase transition in Au-doped Mn4N epitaxial films, similar to In-doped Mn4N epitaxial films.
Article
Nanoscience & Nanotechnology
Tomohiro Yasuda, Taro Komori, Taku Hirose, Takumi Horiuchi, Kaoru Toko, Takashi Suemasu
Summary: Rare-earth-free Mn4N is a promising spintronic material with ferrimagnetism, perpendicular magnetic anisotropy, and controllable magnetic properties. In this study, Mn4-xSnxN epitaxial films (x = 0-1.4) with thickness of about 25 nm were grown on MgO(001) substrates by molecular beam epitaxy. The lattice constants and magneto-transport properties of these films were investigated. The ratio of out-of-plane lattice constant c to in-plane lattice constant a, c/a, was less than 1 for x < 0.9, but changed to more than 1 for x = 1.0. Surprisingly, the sign of the anomalous Hall effect changed twice with increasing x, indicating a variation in the magnetic structure of the Mn4-xSnxN films. Possible mechanisms for this magnetic structure change include magnetic compensation, ferrimagnetic-ferromagnetic phase transition, and formation of noncollinear magnetic structures.
Article
Physics, Applied
Shohei Fukaya, Kazuhiro Gotoh, Takuya Matsui, Hitoshi Sai, Yasuyoshi Kurokawa, Noritaka Usami
Summary: In this study, a simple method was proposed to investigate the effect of metallization on the surface passivation of titanium oxide (TiO x )/Si heterostructures. The relationship between implied open-circuit voltage (iV (OC)) and photoluminescence (PL) intensity imaging of solar cell precursors before metallization was studied using PL imaging technique. Based on this relationship, the quantitative evaluation of the change in iV (OC) before and after metallization on the TiO x was performed. The results showed that the iV (OC) predicted by the PL measurement decreased by 23-104 mV after metal deposition and had a good agreement with the measured V (OC) in the finished solar cells. The evaluation of iV (OC) by PL measurement provides a useful prediction of V (OC) after metallization, which helps in analyzing the passivation degradation induced by metallization.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Kazuhiro Gotoh, Ryo Ozaki, Motoo Morimura, Aki Tanaka, Yoshiko Iseki, Kyotaro Nakamura, Kazuo Muramatsu, Yasuyoshi Kurokawa, Yoshio Ohshita, Noritaka Usami
Summary: We investigated the effect of B2H6 plasma treatment on p-type hydrogenated amorphous silicon (p-a-Si:H) surfaces for high-performance silicon heterojunction (SHJ) solar cells. The boron concentration at the p-a-Si:H surface increased after the B2H6 plasma treatment, and the specific contact resistance decreased by about one-third. The power conversion efficiency of SHJ solar cells improved due to increased fill factor (FF) resulting from decreased series resistance and increased shunt resistance, which was attributed to the enhanced upward band bending at the heterointerface between transparent conductive oxide (TCO) and p-a-Si:H caused by the B2H6 plasma treatment.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Tomohiro Yasuda, Kenta Amemiya, Takashi Suemasu
Summary: In this study, we successfully fabricated ultrathin Mn4N films with a thickness of around 4 nm and discovered a reversed sign of the anomalous Hall resistivity as the film thickness decreased. X-ray magnetic circular dichroism measurements revealed that the magnetic structure of Mn4N with a thickness of around 4 nm is different from that of conventional ferrimagnetic Mn4N films. These findings are of great importance for studying spin-orbit torque and interfacial Dzyaloshinskii-Moriya interaction in Mn4N ultrathin films.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Kosuke O. Hara, Ryota Takagaki, Keisuke Arimoto, Noritaka Usami
Summary: In this study, the microstructure and its effects on the electrical and optoelectronic properties of BaSi2 films grown by close-spaced evaporation were investigated. It was found that using Si(100) substrates, increasing film thickness and growth temperature can decrease the density of epitaxial domain boundaries, improve carrier lifetime, and enhance the performance of BaSi2 films for photovoltaic applications.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Nanoscience & Nanotechnology
Yuto Kimata, Kazuhiro Gotoh, Satoru Miyamoto, Shinya Kato, Yasuyoshi Kurokawa, Noritaka Usami
Summary: Vehicle-integrated photovoltaics (VIPV) is a promising technology for achieving a decarbonized society in the future. The solar cells used in VIPV require low cost, high efficiency, and the ability to be applied to curved surfaces. One way to meet these requirements is by reducing the thickness of the silicon substrate, although it may result in lower near-infrared light absorption and efficiency. To address this issue, a nanoimprinting method was employed in this study to fabricate submicron-sized light trapping structures (LTSs) on solar cells over a large area. By controlling the parameters such as silica coverage, diameter of silica particles, and etching time, the density, height, and size of LTSs can be controlled, leading to improved light absorption and potential short-circuit current gain.
Article
Engineering, Electrical & Electronic
Koki Nozawa, Takeshi Nishida, Takamitsu Ishiyama, Takashi Suemasu, Kaoru Toko
Summary: The carrier mobility of polycrystalline Ge thin-film transistors has been greatly improved by advanced solid-phase crystallization, offering potential for next-generation electronic devices.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Koki Nozawa, Takeshi Nishida, Takamitsu Ishiyama, Takashi Suemasu, Kaoru Toko
Summary: The carrier mobility of polycrystalline Ge thin-film transistors has greatly improved, thanks to advanced solid-phase crystallization and doping with n-type impurities. Among the dopants tested, P doping was found to be the most effective in enhancing the electron concentration and mobility in Ge layers. This improvement in electron mobility opens up possibilities for advanced electronic devices.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Kenta Yamakoshi, Yutaka Ohno, Kentaro Kutsukake, Takuto Kojima, Tatsuya Yokoi, Hideto Yoshida, Hiroyuki Tanaka, Xin Liu, Hiroaki Kudo, Noritaka Usami
Summary: A comprehensive analysis of optical and photoluminescence images from multicrystalline silicon wafers is conducted using machine learning models, resulting in the establishment of a realistic 3D model that includes the generation point of dislocation clusters. The study reveals the mechanism of dislocation generation and its importance in materials science.
ADVANCED MATERIALS
(2023)
