Article
Nanoscience & Nanotechnology
Hyun Kyu Seo, Jin Joo Ryu, Su Yeon Lee, Kanghyoek Jeon, Hyunchul Sohn, Gun Hwan Kim, Min Kyu Yang
Summary: Novel computing systems are required to process unstructured data with low power and parallel processing, similar to the functionality of the human brain. Research has focused on resistive switching devices and crossbar arrays to mimic the functioning of the human brain in electronic devices. This study highlights improvements in the reliability characteristics of a self-rectifying resistive switching cell and the importance of asymmetric electrodes and linear conductance update for inference performance.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Physical
Yantao Yu, Chunqi Wang, Youquan Wen, Chao Jiang, Isaac Abrahams, Zuojuan Du, Jia Sun, Xiaozhong Huang
Summary: The resistive switching behaviors of nitrogen-doped TiO2 nanorod arrays were investigated, and non-volatile and volatile switching were achieved below and above a relative lattice nitrogen content of 21%, respectively. The volatile devices exhibited spiking and decay features similar to the Leaky Integrate-and-Fire model, and the volatile behavior was attributed to the high defect concentration caused by nitrogen doping.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Engineering, Electrical & Electronic
M. Sinha, S. Neogi, R. Ghosh
Summary: The operating temperature is an important factor in controlling the selectivity of a chemiresistive type sensor for gas/vapor detection. By regulating the temperature dependent adsorption/desorption process, the selectivity of the sensor can be switched between different target gases, making it suitable for practical applications. In this study, a high performance, low temperature, and versatile VOC sensor was developed using hydrothermally synthesized ZnO nanorod networks. The selectivity of the sensor prototype was successfully switched from methanol to formaldehyde by adjusting the operating temperature. The sensor exhibited high sensitivity, selectivity, repeatability, and a low response time, making it a reliable VOC sensor for practical applications.
SENSORS AND ACTUATORS A-PHYSICAL
(2023)
Article
Chemistry, Applied
Sheng Lin, He Ren, Zhi Wu, Lan Sun, Xia-Guang Zhang, Yu-Mei Lin, Kelvin H. L. Zhang, Chang-Jian Lin, Zhong-Qun Tian, Jian-Feng Li
Summary: A direct Z-scheme photoelectrocatalytic electrode based on a WO3-x nanowire-bridged TiO2 nanorod array heterojunction was constructed for overall water splitting and hydrogen evolution. The WO3-x/TiO2 heterojunction exhibited superior photoelectrochemical activity, achieving high rates of hydrogen and oxygen evolution without the need for sacrificial agents or redox mediators. The efficient charge transfer pathway between WO3-x nanowires and TiO2 nanorods, presence of oxygen vacancies in WO3-x, and applied bias potential on the photoelectrode all contributed to the superior overall water splitting performance.
JOURNAL OF ENERGY CHEMISTRY
(2021)
Article
Chemistry, Physical
Yuhang Wang, Zhiquan He, Xubo Lai, Boyang Liu, Yibao Chen, Liuwan Zhang, Fengping Wang
Summary: The resistive switching parameters of anatase phase polycrystalline TiO2 thin film can be controlled by light illumination and oxygen atmosphere, resulting in a forming free bipolar resistive switching effect with ON/OFF ratio over 10^4. Surface potential shift accompanied by resistance switching was reversible, and the device demonstrated good optical erasing performance. The mechanism for the observed switching behavior was confirmed to be charge trapping/detrapping, providing a new way to fabricate controllable and optical erasable resistive switching devices in nanoscale.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Engineering, Electrical & Electronic
Hongjia Song, Yanhang Luo, Xiangli Zhong, Jinbin Wang, Hongxia Guo, Peitian Cong
Summary: The degradation trend and mechanism of the total ionizing dose effects on TiO2 nano-rod arrays (NRAs)-based resistive random access memory (ReRAM) were studied. The results showed that the high resistance state (HRS) decreased with the total dose, while the low resistance state (LRS) remained almost unchanged. X-ray photoelectronspectrometer (XPS) characterization revealed that radiation-induced non-lattice oxygen and oxygen vacancy were the main reasons for the degradation of HRS and RESET voltage. A mathematical model of the I-V curves for ReRAM under irradiation was developed based on the VTEAM model, which showed good agreement with experimental results.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Priya Kaith, Parul Garg, Ashok Bera
Summary: This work explores the potential of spin-coated CuFe2O4 (CFO) thin films as an active material in resistive switching memory (RSM). By adding a TiO2 layer in the conventional device, the limitations of scattered SET and RESET voltages and endurance deterioration were overcome, and additional advantages of multilevel switching and improved temperature stability were achieved. The solution-processed FTO/TiO2/CFO/Ag bilayer device shows stable endurance with a maximum ON/OFF ratio of 100 and exhibits excellent temperature stability up to 250 degrees C. These results enhance the multifunctionality of CFO with the potential of being a low-cost multilevel RSM.
APPLIED PHYSICS LETTERS
(2023)
Article
Chemistry, Multidisciplinary
Jiabao Wang, Zhenkai Ji, Xiuzhen Xu, Tiantian Chen, Bo Chen, Guohua Gao, Jiwei Ma, Xipeng Nie, Xiaobin Xu
Summary: This work presents a hybrid lithographic method for growing TiO2 nanorod arrays with arbitrary patterns. The method combines top-down soft lithography and bottom-up hydrothermal approach. The morphology and density of the nanorods can be controlled by adjusting the precursor concentration, reaction time, temperature, and patterns. The work provides a new strategy for the low-cost and facile preparation of patterned TiO2 nanorod arrays and has potential applications in micro-nano-optoelectronic devices and other fields.
Article
Nanoscience & Nanotechnology
Anjan Kumar Jena, Mousam Charan Sahu, Kannan Udaya Mohanan, Sameer Kumar Mallik, Sandhyarani Sahoo, Gopal K. Pradhan, Satyaprakash Sahoo
Summary: In this study, Ag/TiO2/Pt memristors were fabricated using pulsed laser deposition technique, demonstrating both digital and analog switching behavior, and successfully realizing essential synaptic functions. This work enriches the application of TiO2-based resistive random-access memory and provides further support for low-power neuromorphic computing.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Saurabh Srivastava, Joseph Palathinkal Thomas, Xiaoyi Guan, Kam Tong Leung
Summary: This study introduces a new heterojunction design of oxide multilayer stacking to manipulate the oxidation state, successfully changing the BRS behavior to CRS and constructing a device architecture with a double-junction active matrix to overcome the undesirable sneak current path.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Multidisciplinary Sciences
Senad Bulja, Rose Kopf, Al Tate, Mark Cappuzzo, Dmitry Kozlov, Holger Claussen, Dirk Wiegner, Wolfgang Templ, Dariush Mirshekar-Syahkal
Summary: Resistive switching (RS) of Transition Metal Oxides (TMOs) is a promising option for the development of next generation memory and 6G wireless communication technologies. The exact mechanism of RS is not yet fully understood, but it is believed to involve the formation and rupture of conductive filaments in the oxide materials. The study reveals the differences in switching behavior and resistance between amorphous TiO2 and NiO, with TiO2 showing superior high frequency characteristics. These findings are important for understanding the conduction mechanism in binary/multinary oxides and enabling their use in non-volatile memory and 6G applications.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Ceramics
Lee Doowon, Bae Dongjoo, Kim Sungho, Hee-Dong Kim
Summary: This study investigates the correlation between the resistive switching characteristics and the traps of Zr3N2-based resistive random-access memory (RRAM) devices. It is found that the resistive switching characteristics are closely related to the nitride trap density in the Zr3N2 films, and controlling the nitride trap density is crucial for achieving a stable resistance state.
CERAMICS INTERNATIONAL
(2022)
Article
Materials Science, Multidisciplinary
Min Ju Yun, Doowon Lee, Sungho Kim, Christian Wenger, Hee-Dong Kim
Summary: This study reports the formation of free/self-rectifying resistive switching characteristics in a crystalline HfO2-based resistive switching memory device, which exhibits resistive switching behaviors without the need for a forming process. Additionally, the resistive switching performance is improved when using a top electrode with a lower work function.
MATERIALS CHARACTERIZATION
(2021)
Article
Engineering, Electrical & Electronic
Arnab Hazra, Radha Bhardwaj
Summary: The resistive switching phenomenon was measured in an SrTiO3/TiO2 heterostructured nanotube array. The morphology and defect density of the nanotubes were significantly altered due to the growth of SrTiO3. The best-performing material was synthesized with a 2.5 mM precursor, exhibiting an ROFF/RON ratio of approximately 12, with excellent retention and endurance characteristics.
ACS APPLIED ELECTRONIC MATERIALS
(2023)
Article
Chemistry, Analytical
Xuan Wang, Yuanlong Qin, Xinyu Zhang, Yumin Leng, Zhengbo Chen
Summary: An electrochemical aptasensor was constructed using Au/TiO2 nanorod arrays for ultrasensitive detection of adenosine. The aptasensor showed linear correlation between the peak SWV current values and the logarithmic concentration of adenosine, with a minimum detection limit of 0.42 fM. The aptasensor exhibited high specificity, precision, stability, and applicability for adenosine, providing a promising clinical diagnostic tool for adenosine detection.
MICROCHEMICAL JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Yalun Tang, Chi-Hsin Huang, Kenji Nomura
Summary: A cost-effective, vacuum-free liquid-metal-printed 2D tin-doped indium oxide (ITO) thin-film transistor (TFT) was developed, and its performance and characteristics were studied. The main factor contributing to the differences in device performance was found to be the shallow acceptor-like in-gap defects in the midgap region.
Article
Physics, Applied
Kornelius Tetzner, Kingsley Egbo, Michael Klupsch, Ralph-Stephan Unger, Andreas Popp, Ta-Shun Chou, Saud Bin Anooz, Zbigniew Galazka, Achim Trampert, Oliver Bierwagen, Joachim Wuerfl
Summary: In this work, SnO/beta-Ga2O3 heterojunction vertical diodes and lateral field-effect transistors for power electronic applications were realized. The deposited films of p-type SnO on n-type (100) beta-Ga2O3 showed excellent electrical characteristics. The heterojunction diodes and field-effect transistors exhibited stable performance and demonstrated state-of-the-art electrical properties.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Zbigniew Galazka, Steffen Ganschow, Palvan Seyidov, Klaus Irmscher, Mike Pietsch, Ta-Shun Chou, Saud Bin Anooz, Raimund Grueneberg, Andreas Popp, Andrea Dittmar, Albert Kwasniewski, Manuela Suendermann, Detlef Klimm, Thomas Straubinger, Thomas Schroeder, Matthias Bickermann
Summary: Two inch diameter highly conducting (Si-doped) beta-Ga2O3 single crystals with high structural quality and surface smoothness were grown by the Czochralski method, making them suitable substrates for homoepitaxy and electronic device fabrication.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Ying-Chun Shen, Cheng-Yu Lee, Hsing-Hsiang Wang, Ming-Hsuan Kao, Po-Cheng Hou, Yen-Yu Chen, Wen-Hsien Huang, Chang-Hong Shen, Yu-Lun Chueh
Summary: Researchers have developed a flexible photodetector based on a two-dimensional Sb2Se3 film, which exhibits high photosensing current and detection ranges from visible to near-infrared. The photodetector was fabricated using an efficient field-effect transistor platform and showed quick response times and broadband absorption.
Article
Physics, Applied
Ta-Shun Chou, Palvan Seyidov, Saud Bin Anooz, Raimund Grueneberg, Mike Pietsch, Jana Rehm, Thi Thuy Vi Tran, Kornelius Tetzner, Zbigniew Galazka, Martin Albrecht, Klaus Irmscher, Andreas Fiedler, Andreas Popp
Summary: This study investigated the MOVPE of (100) beta-Ga2O3 films for high-power electronic devices. A height-adjustable showerhead close to the susceptor was crucial in increasing the stability of the Ga wetting layer on the surface and reducing parasitic particles. The achieved film thickness was up to 3 μm with a low root mean square value, and record carrier mobilities were observed at room temperature.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Environmental
Wen-Jun Niu, Ying-Yun Yan, Ru-Ji Li, Wei-Wei Zhao, Jiang-Lei Chen, Ming-Jin Liu, Bingni Gu, Wen-Wu Liu, Yu-Lun Chueh
Summary: In this proof-of-concept study, Fe nanoparticles encapsulated by nitrogen-doped carbon were evaluated and compared to Fe single atoms for boosting the catalytic activity of the oxygen reduction reaction (ORR) in Znair batteries. The Fe single atoms and Fe nanoparticles embedded in nitrogen-doped carbon exhibited excellent ORR performance with good stability and remarkable methanol tolerance. The strong interaction between the atomically dispersed Fe-Nx and adjacent Fe nanoparticles alters the electronic structure and enhances the electrocatalytic kinetics.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Physics, Applied
Ta-Shun Chou, Palvan Seyidov, Saud Bin Anooz, Raimund Grueneberg, Jana Rehm, Tran Thi Thuy Vi, Andreas Fiedler, Kornelius Tetzner, Zbigniew Galazka, Martin Albrecht, Andreas Popp
Summary: In this study, the development of unwanted parasitic particles in the MOVPE chamber during the growth of mu m level films is comprehensively investigated. The density of parasitic particles is observed to be significant at film thicknesses starting from >1.5 to 2 mu m. These particles induce structural defects, such as twin lamellae, which adversely affect the electrical properties of the grown film. The parasitic particles originate from parasitic reactions within the chamber triggered by the promoted gas-phase reactions during the growth process, and their density can be reduced by increasing total gas flow and reducing the showerhead distance to the susceptor. After minimizing the density of parasitic particles, film thicknesses up to 4 mu m have been achieved. RT Hall measurements reveal carrier mobilities of 160 cm(2)V(-1)s(-1) at carrier concentrations of 5.7 x 10(16) cm(-3).
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Zbigniew Galazka, Andreas Fiedler, Andreas Popp, Steffen Ganschow, Albert Kwasniewski, Palvan Seyidov, Mike Pietsch, Andrea Dittmar, Saud Bin Anooz, Klaus Irmscher, Manuela Suendermann, Detlef Klimm, Ta-Shun Chou, Jana Rehm, Thomas Schroeder, Matthias Bickermann
Summary: We studied the growth and physical properties of β-(AlxGa1-x)(2)O-3 single crystals with different Al contents using the Czochralski method. The Al segregation coefficient in the Ga2O3 melt resulted in higher Al content in the crystals. By co-doping with Si or Mg, we obtained semiconducting, degenerately semiconducting, or semi-insulating crystals. The lattice constants decreased anisotropically, while the optical bandgap increased linearly with Al content.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Crystallography
Ta-Shun Chou, Saud Bin Anooz, Raimund Grueneberg, Thuy Vi Thi Tran, Jana Rehm, Zbigniew Galazka, Andreas Popp
Summary: Si-doped beta-Ga2O3 layers were grown on (100) beta-Ga2O3 semi-insulating substrates by MOVPE, and their reflection spectrum on the substrate surface was investigated. Transforming the reflectance spectrum into the autocorrelation domain revealed a more pronounced Fabry-Pe 'rot oscillation, which allowed for easy estimation of the growth rate and growth mode based on the period and damping behavior of the spectrum. The observed oscillation contributed to the refractive index difference between the substrate and the film caused by impurities and preparation techniques. The high sensitivity of reflectance spectroscopy demonstrated its advantage as a powerful growth process monitoring tool.
JOURNAL OF CRYSTAL GROWTH
(2023)
Article
Chemistry, Multidisciplinary
Mayur Chaudhary, Tzu-Yi Yang, Chieh-Ting Chen, Po-Chien Lai, Yu-Chieh Hsu, Yu-Ren Peng, Ashish Kumar, Chih-Hao Lee, Yu-Lun Chueh
Summary: This study demonstrates that the diffusion of metal ions can be modulated by defects in the switching medium, leading to the confinement of metal filaments in a precise 1D channel. This filament confinement achieved through defect engineering enables two interchangeable switching modes and could potentially address speed, size, and energy issues in computing.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Physics, Applied
Kornelius Tetzner, Michael Klupsch, Andreas Popp, Saud Bin Anooz, Ta-Shun Chou, Zbigniew Galazka, Karina Ickert, Mathias Matalla, Ralph-Stephan Unger, Eldad Bahat Treidel, Mihaela Wolf, Achim Trampert, Joachim Wuerfl, Oliver Hilt
Summary: In this work, vertical (100) beta-Ga2O3 FinFET devices were realized for power electronics applications. The devices were fabricated on highly conducting (100) beta-Ga2O3 substrates and epitaxially grown layers with specific doping concentrations for the drift and channel regions. The fabricated FinFET devices showed enhancement-mode properties and measured breakdown strength.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Coatings & Films
Kornelius Tetzner, Andreas Thies, Palvan Seyidov, Ta-Shun Chou, Jana Rehm, Ina Ostermay, Zbigniew Galazka, Andreas Fiedler, Andreas Popp, Joachim Wuerfl, Oliver Hilt
Summary: In this study, the optimum annealing conditions for activating Ge-implanted beta-Ga2O3 were analyzed to achieve low ohmic contact resistances. Pulsed rapid thermal annealing treatment was conducted at temperatures between 900 and 1200 degrees C in a nitrogen atmosphere. The results showed that high-temperature annealing above 1000 degrees C led to increased surface roughness and significant redistribution of implanted Ge. However, annealing at 1100 degrees C resulted in a significant reduction in specific contact resistance, reaching a record value of 4.8 x 10(-7) Omega cm(2) with an implantation activation efficiency of 14.2%. The highest activation efficiency of 19.2% and lowest sheet resistances were achieved at 1200 degrees C, but the ohmic contact properties were inferior due to severe increase in surface roughness. These findings demonstrate the high potential of high-temperature annealing processes above 1000 degrees C for achieving low ohmic contact resistances in beta-Ga2O3.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Nanoscience & Nanotechnology
Kuangye Wang, Ling Lee, Sueh Liang Loo, Tzu-Yi Yang, Chieh-Ting Chen, Tzu-Wen Kuo, Jeng-Lung Chen, Hao-chung Kuo, Yu-Lun Chueh
Summary: Nitrogen-doped molybdenum diselenide (MoSe2) films with nanoscaled thicknesses were fabricated by ionizing N2 carrier gas in a plasma-assisted chemical vapor reaction furnace. The amount of nitrogen doping was controlled by the relative flow rate of N2. The nitrogen doping at different depths in the MoSe2 films resulted in different responses to NH3 and NO2 gases.
ACS APPLIED NANO MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Ying-Chun Shen, Yu-Wen Huang, Tzu-Yi Yang, Yi-Jen Yu, Hao-Chung Kuo, Tseung-Yuen Tseng, Yu-Lun Chueh
Summary: Al2O3 sandglass nanostructures (SNGSs) and AlN layer are used to prevent the overinjection of cations and localize the growth of conducting filaments in HfO (x) -based CBRAMs. The Cu/Al2O3 SNGSs/HfO (x) /AlN/TiN device shows stable on/off ratio for more than 6000 cycles, and the Te/Al2O3 SNGSs/HfO (x) /AlN/TiN device exhibits multilevel cell characteristic and excellent potentiation and depression nonlinearities.
ACS APPLIED NANO MATERIALS
(2023)
Article
Nanoscience & Nanotechnology
Yu-Chieh Hsu, Yan-Yu Chen, Jia-Min Shieh, Wen-Hsien Huang, Chang-Hong Shen, Yu-Lun Chueh
Summary: A pulsed laser annealing method is used to directly synthesize nickel silicide (NiSi) as a contact material to improve the contact of electric devices. The integration of NiSi into different devices significantly improves their performance.
ADVANCED ELECTRONIC MATERIALS
(2023)
