Article
Engineering, Electrical & Electronic
Zhengpeng Wang, Hehe Gong, Chenxu Meng, Xinxin Yu, Xinyu Sun, Chongde Zhang, Xiaoli Ji, Fangfang Ren, Shulin Gu, Youdou Zheng, Rong Zhang, Jiandong Ye
Summary: Defects/traps in beta-Ga2O3 have been investigated and identified in Ni/beta-Ga2O3 Schottky barrier diode (SBD) and NiO/beta-Ga2O3 p(+)-n heterojunction diode (HJD) by deep level transient spectroscopy (DLTS). The study provides insights into the carrier transport mechanisms in Ga2O3-based power devices.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Chemistry, Physical
Oskar Sachnik, Xiao Tan, Dehai Dou, Constantin Haese, Naomi Kinaret, Kun-Han Lin, Denis Andrienko, Martin Baumgarten, Robert Graf, Gert-Jan A. H. Wetzelaer, Jasper J. Michels, Paul W. M. Blom
Summary: A common obstacle in organic semiconductors is the unipolar charge transport caused by trapping of either electrons or holes by extrinsic impurities. In this study, a molecular strategy is proposed to spatially separate the highest occupied and lowest unoccupied molecular orbitals, effectively preventing charge trapping and significantly enhancing charge transport. This strategy opens up possibilities for large band gap organic semiconductors with balanced and trap-free transport.
Article
Nanoscience & Nanotechnology
Domenic Prete, Valeria Demontis, Valentina Zannier, Maria Jesus Rodriguez-Douton, Lorenzo Guazzelli, Fabio Beltram, Lucia Sorba, Francesco Rossella
Summary: We fabricated dual-gated electric double layer (EDL) field effect transistors based on InAs nanowires gated with an ionic liquid, and performed electrical transport measurements at different temperatures. The study found that adjusting the spatial distribution of ions in the ionic liquid can induce doping in the nanostructures, and the carrier concentration and mobility are significantly affected by the liquid gate voltage changes.
Article
Materials Science, Multidisciplinary
Salvatore Gambino
Summary: The study found that a prototypical conjugated polymer does not show any preference for the transport of electrons or holes, exhibiting ambipolar charge transport. The presence of traps and unintentional p-doping makes it difficult to address the intrinsic nature of the charge transport mechanism. Analysis of experimental data revealed that the charge transport of holes is mainly governed by energetic disorder, while the electrons' conduction is controlled by both energetic and positional disorder.
Article
Nanoscience & Nanotechnology
Sushrut Modak, Leonid Chernyak, Alfons Schulte, Corinne Sartel, Vincent Sallet, Yves Dumont, Ekaterine Chikoidze, Xinyi Xia, Fan Ren, Stephen J. Pearton, Arie Ruzin, Denis M. Zhigunov, Sergey S. Kosolobov, Vladimir P. Drachev
Summary: Electron beam-induced current was used to measure the minority carrier diffusion length in p-Ga2O3 thin films grown through metal-organic chemical vapor deposition at temperatures ranging from 304 to 404 K. The diffusion length of electrons decreased as the temperature increased. Additionally, cathodoluminescence emission spectroscopy identified optical signatures of acceptor levels associated with the V-Ga(-)-V-O(++) defect complex. The activation energies for the decrease in diffusion length and the quenching of cathodoluminescence emission with increasing temperature were attributed to the thermal de-trapping of electrons from the V-Ga(-)-V-O(++) defect complexes.
Article
Chemistry, Multidisciplinary
Beom Jun Kim, Sang Wook Kang
Summary: Polarized silver nanoparticles (AgNPs) were used as carriers for CO2 separation through facilitated transport. The addition of p-benzoquinone (p-BQ) polarized and stabilized the AgNPs. The polymeric composite membrane exhibited high selectivity for CO2/N2 separation, with ideal selectivity of 117 or more. This improvement was attributed to the selective and reversible interaction between polar CO2 molecules and the polarized AgNPs facilitated by p-BQ. XPS analysis revealed a positive charged density on the surface of the particles, which enhanced the transport of CO2 molecules through dipole-dipole interaction.
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Weijian Tao, Leilei Zhu, Kanghua Li, Chao Chen, Yuzhong Chen, Yujie Li, Xufeng Li, Jiang Tang, Honghui Shang, Haiming Zhu
Summary: This study reports the electronic and structural dynamics of excited state self-trapping in antimony chalcogenides, providing atomic-level characterizations using ultrafast spectroscopy and DFT calculations. The findings provide conclusive evidence of carrier self-trapping arising from intrinsic lattice anharmonicity and polaronic effect, and offer a new understanding of excited state properties in soft semiconductor materials.
Article
Engineering, Electrical & Electronic
Haolan Qu, Jiaxiang Chen, Yu Zhang, Jin Sui, Ruohan Zhang, Junmin Zhou, Xing Lu, Xinbo Zou
Summary: The properties of a minority carrier (hole) trap in ss-Ga2O3 have been investigated using a NiO/ss-Ga2O3 p-n heterojunction. The activation energy for emission and the hole capture cross section were determined to be 0.10 eV and 2.48 x 10(-15) cm(2), respectively. Temperature-enhanced capture and emission kinetics were observed, and it was found that the emission process of the minority carrier trap is independent of the electric field.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Wei Lu, Zipu Fan, Yunkun Yang, Junchao Ma, Jiawei Lai, Xiaoming Song, Xiao Zhuo, Zhaoran Xu, Jing Liu, Xiaodong Hu, Shuyun Zhou, Faxian Xiu, Jinluo Cheng, Dong Sun
Summary: This study reveals the transient photothermoelectric response of Dirac semimetallic Cd3As2, namely the photo-Seebeck effect and photo-Nernst effect, by studying the terahertz emission from the transient photocurrent induced by these effects. The response clearly indicates an order of magnitude enhancement on transient photothermoelectric current generation when a weak magnetic field is applied. These results highlight the enhancement of thermoelectric performance can be achieved in topological Dirac semimetals based on the Nernst effect.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Christopher Perez, Atharv Jog, Heungdong Kwon, Daniel Gall, Mehdi Asheghi, Suhas Kumar, Woosung Park, Kenneth E. Goodson
Summary: In this study, time-domain thermoreflectance was used to uncover cross-plane heat conduction mechanisms in high aspect ratio metal nanostructures. The findings demonstrate the existence of unexplored heat transport modes in nanostructured metals, which can be utilized to develop electro-thermal solutions for modern microelectronic devices and sensors.
ADVANCED FUNCTIONAL MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Shuai Fu, Enquan Jin, Hiroki Hanayama, Wenhao Zheng, Heng Zhang, Lucia Di Virgilio, Matthew A. Addicoat, Markus Mezger, Akimitsu Narita, Mischa Bonn, Klaus Muellen, Hai Wang
Summary: Two-dimensional covalent organic frameworks (2D COFs) are crystalline porous polymers with well-defined open nanochannels. This study reveals that TPB-TFB COF thin films exhibit high photoconductivity with long charge scattering time and high charge carrier mobility at room temperature.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Materials Science, Multidisciplinary
Congcong Ma, Zhengyuan Wu, Zhuoxun Jiang, Ying Chen, Wei Ruan, Hao Zhang, Heyuan Zhu, Guoqi Zhang, Junyong Kang, Tong-Yi Zhang, Junhao Chu, Zhilai Fang
Summary: This study demonstrates the p-type conductivity of N-doped beta-Ga2O3, opening up new possibilities for the fabrication of high-performance devices.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Materials Science, Multidisciplinary
Zhengpeng Wang, He-He Gong, Xin-Xin Yu, Xiaoli Ji, Fang-Fang Ren, Yi Yang, Shulin Gu, Youdou Zheng, Rong Zhang, Jiandong Ye
Summary: This study investigates the fundamental correlation of carrier transport, trapping, and recombination kinetics in NiO/beta-Ga2O3 heterojunction power diodes. The findings reveal that majority carrier trap states dominate the trap-assisted tunneling process in the forward conduction regime, while minority carrier diffusion is important at higher biases. The leakage mechanism at high reverse biases is governed by Poole-Frenkel emissions through beta-Ga2O3 bulk traps.
SCIENCE CHINA-MATERIALS
(2023)
Article
Physics, Applied
Jian-Sian Li, Chao-Ching Chiang, Xinyi Xia, Sergei Stepanoff, Aman Haque, Douglas E. Wolfe, Fan Ren, S. J. Pearton
Summary: NiO/Ga2O3 heterojunction rectifiers were irradiated with 1 Mrad of Co-60 gamma-rays, resulting in a 1000x reduction in forward current, a 100x increase in reverse current, and a significant decrease in the on-off ratio. The carrier concentration in the Ga2O3 drift region slightly decreased, indicating a reversible effect. The rectifiers showed no permanent ionizing dose effects and resistance to displacement damage, suggesting potential applications in harsh radiation environments with appropriate bias sequences.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Hitoshi Takane, Hirokazu Izumi, Hajime Hojo, Takeru Wakamatsu, Katsuhisa Tanaka, Kentaro Kaneko
Summary: The carrier transport mechanism in Si-doped n-type alpha-Ga2O3 thin film on m-plane sapphire substrate was investigated. The study found that the carrier transport mechanism in alpha-Ga2O3 with high dislocation density differs depending on whether alpha-Ga2O3 is degenerate or non-degenerate. It was also estimated that dislocation densities below approximately 1 x 10^7-1 x 10^8 cm^-2 will be required for lightly doped drift layers in devices.
JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Engineering, Electrical & Electronic
Chao-Ching Chiang, Chan-Wen Chiu, Fan Ren, Cheng-Tse Tsai, Yu-Te Liao, Josephine F. Esquivel-Upshaw, Stephen J. Pearton
Summary: This study presents a SARS-CoV-2 virus detection mechanism using stored disposable strips. The accuracy of this sensing platform is comparable to PCR and provides results in less than 30 seconds. The disposable strips, biofunctionalized with SARS-CoV-2 antibodies, detect the virus in saliva samples, and the detected signals are amplified and displayed on an LCD screen. The system demonstrates the ability to show qualitative results within 30 seconds and quantitative concentrations in 5 minutes.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Engineering, Electrical & Electronic
Minghan Xian, Jenna L. Stephany, Chan-Wen Chiu, Chao-Ching Chiang, Fan Ren, Cheng-Tse Tsai, Siang-Sin Shan, Yu-Te Liao, Josephine F. Esquivel-Upshaw, Stephen J. Pearton
Summary: Oral squamous cell carcinoma is a common type of lip and oral cavity cancer, which requires early detection for improved survival rates. A modular biological sensor utilizing transistor-based technology has been developed for rapid and accurate point of care detection of the cancer, providing opportunities for quick clinical diagnosis.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Physics, Applied
Md Abu Jafar Rasel, Nahid Sultan Al-Mamun, Sergei Stepanoff, Aman Haque, Douglas E. Wolfe, Fan Ren, Stephen J. Pearton
Summary: In this work, we illustrate the rejuvenation of degraded Ti/4H-SiC Schottky barrier diodes at room temperature within seconds by utilizing high-energy electron interactions with defects. By applying high current density electrical pulsing with low frequency and duty cycle to suppress temperature rise, we successfully decrease defect concentration and improve device performance beyond the pristine condition. The ultrafast and room temperature process has the potential to rejuvenate electronic devices in high power and harsh environmental conditions.
APPLIED PHYSICS LETTERS
(2023)
Article
Crystallography
Jian-Sian Li, Hsiao-Hsuan Wan, Chao-Ching Chiang, Xinyi Xia, Timothy Jinsoo Yoo, Honggyu Kim, Fan Ren, Stephen J. Pearton
Summary: Vertical heterojunction rectifiers with p-type NiO and thick Ga2O3 drift layers grown on Sn-doped β-Ga2O3 substrates exhibited breakdown voltages > 8 kV. Low drift doping concentration, low power during NiO deposition, and the formation of a guard ring were key factors for achieving excellent performance. These results demonstrate the potential of NiO/Ga2O3 rectifiers beyond SiC and GaN.
Article
Engineering, Electrical & Electronic
Sergei P. Stepanoff, Aman Haque, Fan Ren, Stephen Pearton, Douglas E. Wolfe
Summary: The susceptibility of electronics to radiation increases as the size and complexity of electronic chips or systems increase. This study develops an indirect technique to identify radiation-susceptible regions and demonstrates its effectiveness in rapid detection.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Engineering, Multidisciplinary
Pierre-Alexandre Bliman, Yves Dumont, Oscar Eduardo Escobar-Lasso, Hector J. Martinez-Romero, Olga Vasilieva
Summary: Laboratory experiments and field essays have shown that introducing the intracellular bacterium Wolbachia into female Aedes spp mosquitoes significantly reduces their ability to transmit dengue virus and other mosquito-borne viral diseases. However, Wolbachia-infected female mosquitoes still need to feed on human blood, while male mosquitoes, whether wild or carrying Wolbachia, do not bite humans. Therefore, the massive release of Wolbachia-carrying females may increase both nuisance and epidemiological risk in human populations. This paper presents a simple model that explores the practical aspects of introducing Wolbachia through male-biased releases and investigates the minimum number of mosquitoes and time required to achieve population replacement.
APPLIED MATHEMATICAL MODELLING
(2023)
Article
Chemistry, Physical
Chao-Ching Chiang, Xinyi Xia, Jian-Sian Li, Fan Ren, S. J. Pearton
Summary: The 8-polytype of Ga2O3 is a promising material for next generation power electronics and solar-blind UV photodetectors due to its high critical electric field strength and ability to be grown as large diameter single crystals. Dry etching is being focused on for patterning such devices, but it may cause surface modification and damage to the material. This study demonstrates that dry etch damage in 8-Ga2O3 leads to a reduction in near-surface carrier concentration, affecting device parameters like on-state resistance and introducing trap-assisted space-charge-limited conduction in the damaged layers.
APPLIED SURFACE SCIENCE
(2023)
Article
Materials Science, Multidisciplinary
Jian-Sian Li, Xinyi Xia, Chao-Ching Chiang, Hsiao-Hsuan Wan, Fan Ren, Jihyun Kim, S. J. Pearton
Summary: Neutrons generated by charge-exchange reactions were used to irradiate Schottky Ga2O3 rectifiers and NiO/Ga2O3 p-n heterojunction rectifiers. The breakdown voltage was improved for Schottky rectifiers but highly degraded for their NiO/Ga2O3 counterparts. The switching characteristics were degraded for both types of devices after irradiation.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Jian-Sian Li, Chao-Ching Chiang, Xinyi Xia, Hsiao-Hsuan Wan, Fan Ren, S. J. Pearton
Summary: Large area vertical NiO/β n-Ga2O/n(+) Ga2O3 heterojunction rectifiers with high breakdown voltage (3.6 kV) and large conducting currents (4.8 A) are demonstrated. The performance exceeds the unipolar 1D limit for GaN, indicating the potential of β-Ga2O3 for future high-power rectification devices. The breakdown voltage is strongly dependent on the carrier concentration in the drift region.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2023)
Article
Crystallography
Jian-Sian Li, Hsiao-Hsuan Wan, Chao-Ching Chiang, Fan Ren, Stephen J. Pearton
Summary: The stability of vertical geometry NiO/Ga2O3 rectifiers was examined under two types of annealing. It was found that annealing at 300 degrees C resulted in the best performance, including maximizing breakdown voltage and on-off ratio, lowering forward turn-on voltage, reducing reverse leakage current, and maintaining on resistance. The surface morphology remained smooth and the NiO exhibited a bandgap of 3.84 eV with an almost unity Ni2O3/NiO composition.
Article
Crystallography
Chao-Ching Chiang, Jian-Sian Li, Hsiao-Hsuan Wan, Fan Ren, Stephen J. Pearton
Summary: Ga2O3 heterojunction rectifiers with NiO as the solution on the p-type side have become a novel candidate for power conversion applications. In this study, the optimized design of high-breakdown NiO/Ga2O3 rectifiers was examined using the Silvaco TCAD simulator to determine the electric field distribution. The doping concentration, guard ring thickness, and extension beyond the anode were all important factors in determining the breakdown location. The transition phenomenon from the edge of the NiO extension to the top contact periphery was found to be correlated with the depletion effect.
Article
Materials Science, Multidisciplinary
Jian-Sian Li, Chao-Ching Chiang, Xinyi Xia, Hsiao-Hsuan Wan, Fan Ren, S. J. Pearton
Summary: NiO/β-Ga2O3 vertical rectifiers show near-temperature-independent breakdown voltages (V-B) of >8 kV at 600 K. The power figure of merit (V-B)²/R-ON for 100 μm diameter devices is 9.1 GW cm(-2) at 300 K and 3.9 GW cm(-2) at 600 K. In contrast, Schottky rectifiers on the same wafers have V-B of about 1100 V at 300 K with a negative temperature coefficient of breakdown. The power figure of merit for Schottky rectifiers is much lower compared to the heterojunction rectifiers. The results demonstrate the potential of using transparent oxide heterojunctions for high temperature, high voltage applications.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Review
Engineering, Electrical & Electronic
S. J. Pearton, Xinyi Xia, Fan Ren, Md Abu Jafar Rasel, Sergei Stepanoff, Nahid Al-Mamun, Aman Haque, Douglas E. Wolfe
Summary: Wide bandgap semiconductors SiC and GaN are used in power electronics and light-emitting diodes. They have higher radiation hardness compared to Si devices due to larger threshold energies for creating defects and high rates of defect recombination. However, heavy-ion-induced catastrophic burnout commonly occurs in SiC and GaN power devices. Light-emitting devices are not affected by this mechanism. Strain has also been identified as a parameter affecting radiation susceptibility of wide bandgap devices.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Engineering, Electrical & Electronic
Chao-Ching Chiang, Hsiao-Hsuan Wan, Jian-Sian Li, Fan Ren, Timothy Jinsoo Yoo, Honggyu Kim, S. J. Pearton
Summary: Sputtered p-NiO films were used to suppress gate leakage and produce a positive shift in the gate voltage of AlGaN/GaN high-electron mobility transistors for e-mode operation. The utility of NiO gates in increasing the on-off ratio and shifting the threshold voltage in comparison to Schottky gates was demonstrated.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
(2023)
Article
Mathematics, Applied
J. Banasiak, Y. Dumont, I. V. Yatat Djeumen
Summary: This paper addresses two main issues of monotone impulsive reaction-diffusion equations: the existence of traveling waves and the computation of spreading speeds. It applies the methodology to a planar system of impulsive reaction-diffusion equations that models tree-grass interactions in fire-prone savannas. Numerical simulations are provided to support the theoretical results.
DIFFERENTIAL EQUATIONS AND DYNAMICAL SYSTEMS
(2023)
