Article
Physics, Condensed Matter
Sergiy Khartsev, Nils Nordell, Mattias Hammar, Juris Purans, Anders Hallen
Summary: Pulsed laser ablation is used to form high-quality silicon-doped beta-Ga(2)O(3)films on sapphire by depositing Ga(2)O(3)and Si from two separate sources, achieving a single crystallinity with a Si concentration of about 1 x 10(20) cm(-3) for optimal electrical performance. Depositing Si and Ga(2)O(3)from two separate sources leads to high crystalline quality and a mobility of about 2.9 cm(2) (V s)(-1).
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS
(2021)
Article
Physics, Applied
Taiga Fudetani, Kohei Ueno, Atsushi Kobayashi, Hiroshi Fujioka
Summary: Silicon-doped GaN grown using pulsed sputtering deposition showed promising characteristics when applied as tunneling junction contacts in nitride-based optoelectronic devices, with lower differential resistance and stable performance under high injection currents.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Condensed Matter
A. Mandal, S. K. Adhi, B. P. Joshi, S. D. Shinde, A. G. Banpurkar, A. V. Limaye, K. P. Adhi, T. Sant, S. M. Jejurikar
Summary: Highly c-axis oriented, single-phase praseodymium doped ZnO thin films were deposited on cAl(2)O(3) substrate under different oxygen pressure conditions. Photoluminescence and X-ray photoelectron emission studies revealed the emission of Pr3+ ions and observed different transitions of Pr3+ ions.
PHYSICA B-CONDENSED MATTER
(2021)
Article
Chemistry, Physical
Xinyu Shen, Hua Wu, Xiaoyu Zhang, Meili Xu, Junhua Hu, Jinyang Zhu, Bin Dong, William W. Yu, Xue Bai
Summary: The all-solution process for inorganic perovskite nanocrystals (PNCs) LEDs shows great potential for new-generation illumination and displays, but the challenge lies in the injection barriers and charge injection imbalance. The introduction of CBP into the hole transport layer (HTL) efficiently modulates the charge carrier mobility and energy level, resulting in barrier-free charge injection and optimal performance for solution-processed PNC LEDs. The luminance of red LEDs reaches 2990 cd m(-2) and the external quantum efficiency achieves 8.1%, with improved turn-on voltage and roll-off due to more balanced charge injection.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Engineering, Environmental
Jie Guo, Qiang Hu, Min Lu, Asu Li, Xiaoyu Zhang, Ren Sheng, Ping Chen, Yu Zhang, Jinlei Wu, Yuhao Fu, Guang Sun, William W. Yu, Xue Bai
Summary: Research shows that doping CsCdBr3 NRs with Pb2+ can significantly improve their optoelectronic properties, resulting in a blue emission with a quantum yield of 48% and centered at 459 nm. Additionally, using the optimized NRs as the emissive layer, a blue perovskite LED based on 1D NRs was successfully fabricated.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Optics
Zhe Zhuang, Daisuke Iida, Martin Velazquez-Rizo, Kazuhiro Ohkawa
Summary: The study introduced a method for fabricating ultra-small InGaN μLEDs, successfully realizing different shapes of green μLEDs. It was found that as the size of the μLED decreases, the series resistance and turn-on voltage increase, while the light output power density and external quantum efficiency also improve.
Article
Engineering, Electrical & Electronic
Reeson Kek, Guang Liang Ong, Seong Ling Yap, Lian Kuang Lim, Song Foo Koh, Chen Hon Nee, Teck Yong Tou, Seong Shan Yap
Summary: This study investigates the deposition of nanostructures by room temperature pulsed laser deposition (PLD) in low pressure gases (O-2, N-2, He, and Ar) at different substrate positions. The results show that different gases have different effects on optical emission and ion velocity. It is suggested that collisions of the ablated specie result in strong emission and impede the ion velocity. Amorphous films are obtained in all gases at the on-axis/center position and in O-2 at the bottom position. Crystalline ZnO and Zn nanostructures are deposited at the bottom position in N-2, He, and Ar. The presence of nanorods is detected in Ar. Zn crystallites are also detected, which can act as catalyst for nanostructure formation.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2022)
Article
Physics, Applied
Tian-Run Zhang, Ya-Nan Wang, Yue-Feng Liu, Jing Feng
Summary: A transparent ultrathin Ag nanomesh electrode was fabricated using nanosphere lithography and a dielectric wetting layer. The nanomesh electrode exhibited higher figure of merit and improved optical and electrical performance compared to traditional ultrathin film Ag electrodes.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
Young Joon Han, Kyung-Tae Kang, Kwan Hyun Cho
Summary: The study found that different film-formation methods can affect the optimal annealing temperature for zinc oxide nanoparticle electron transport layer under intense pulsed light conditions. Spin-coated and inkjet-printed ZnO NP ETLs exhibit different surface morphologies after IPL post-treatment.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Chemistry, Multidisciplinary
Islam Mohammad Shafiqul, Raj Deep, Jie Lin, Toshiyuki Yoshida, Yasuhisa Fujita
Summary: In this study, nitrogen-doped zinc oxide nanoparticles were successfully synthesized using the gas evaporation method with DC arc plasma. The nitrogen concentration was found to have an impact on the Raman spectra and photoluminescence spectra of the nanoparticles.
Article
Materials Science, Multidisciplinary
Dongwen Gao, Li Wang, Xueqiong Su, Jin Wang, Ruixiang Chen
Summary: This study investigated the impact of a magnetic field on the optical properties of Co-doped ZnS nano films. By manipulating the growth structure of the film during deposition using a magnetic environment, the optical properties were enhanced. Experimental results under magnetic field conditions were consistent with simulation results, confirming the improved optical properties.
Article
Chemistry, Physical
Islam Mohammad Shafiqul, Toshiyuki Yoshida, Yasuhisa Fujita
Summary: Heterojunction light-emitting diodes (LEDs) based on p-type ZnO and n-type ZnMgO nanoparticles have been successfully fabricated. The experimental results show that the LEDs with the p-ZnO/n-ZnMgO/GZO structure exhibit better I-V characteristics and lower leakage current compared to the p-ZnO/GZO LEDs, and the emission intensity is improved by adding the ZnMgO NP layer.
Review
Optics
Mahdiyar Nouri Rezaie, Shahram Mohammadnejad, Shabnam Ahadzadeh
Summary: The review paper discusses various hybrid inorganic/organic light-emitting diodes (I/O LEDs) based on zinc oxide (ZnO) and conjugated polymers, analyzing their structural, electrical, and optical characteristics and applications. Optoelectronic features of these hybrid LEDs are influenced by n-type ZnO nanostructures, and their electroluminescent intensity can be enhanced by selecting suitable p-type conjugated polymers or adding dopants. Challenges, comparisons, and future prospects of these hybrid LEDs, including the use of nanotubes, quantum dots, and perovskite layers, have also been explored.
OPTICS AND LASER TECHNOLOGY
(2021)
Review
Chemistry, Multidisciplinary
Chun Zhou, Wenyuan Meng, Lingmei Kong, Chengxi Zhang, Jianhua Zhang, Fangze Liu, Hongbo Li, Guohua Jia, Xuyong Yang
Summary: Metal halide perovskite light-emitting diodes (PeLEDs) are considered as the next-generation display technology due to their unique optoelectronic properties. However, the commercialization of solution-based PeLEDs still faces challenges. Vacuum deposition techniques offer precise control of film quality and are compatible with organic LED manufacturing process. Improving the efficiency and stability of PeLEDs remains a challenge.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Chemistry, Physical
Xueguo Li, Hao Liang, Changbo Zheng, Chunxiang Zhao, Songchao Bai, Xueqing Zhao, Hao Zhang, Yongsheng Zhu
Summary: Lead-free halide double perovskite crystals (Cs2NaInCl6:Sb3+) with excellent blue emission and the ability for multicolor emissions through lanthanide ion doping were prepared. The emission colors can be continuously adjusted by altering the doping levels of lanthanide ions. The findings provide deep insights for the designing of multicolor double perovskite phosphors.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Materials Science, Coatings & Films
Jian-Sian Li, Xinyi Xia, Chao-Ching Chiang, David C. C. Hays, Brent P. P. Gila, Valentin Craciun, Fan Ren, S. J. Pearton
Summary: The characteristics of sputtered NiO for pn heterojunctions with Ga2O3 were investigated, and it was found that the oxygen/nickel and Ni2O3/NiO ratios, as well as the bandgap and resistivity, increased with the O-2/Ar gas flow ratio. However, the bandgap and Ni2O3/NiO ratio decreased with increasing annealing temperature, resulting in higher film density. The incorporation of hydrogen into NiO during plasma exposure was confirmed, and the band alignments of NiO films with both alpha- and beta-Ga2O3 were determined to have type II-staggered gaps. The breakdown voltage of NiO/beta-Ga2O3 heterojunction rectifiers also varied with the O-2/Ar flow ratio during deposition.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Coatings & Films
Benjamin C. Letson, Simon Barke, Peter Wass, Guido Mueller, Fan Ren, Stephen J. Pearton, John W. Conklin
Summary: The laser interferometer space antenna (LISA), a joint ESA and NASA project, will enable space-based gravitational wave detection. Three identical spacecraft will form a triangular configuration, flying in a drag-free formation around free-falling test masses. To compensate for test mass charging, UV photons with higher energy than gold's work function are needed. The performance of UV light emitting diodes (LEDs) for the LISA mission was characterized under various operating conditions, and degradation was found to be faster at elevated temperatures and in dc conditions. Preselection based on initial spectral ratio and ideality factor showed positive correlation with subsequent reliability. The UV LEDs for LISA are required to support a 2-year cruise and commissioning period, followed by a 4-year science mission.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(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)
Review
Materials Science, Multidisciplinary
Benjamin C. Letson, John W. Conklin, Peter Wass, Simon Barke, Guido Mueller, Md Abu Jafar Rasel, Aman Haque, Stephen J. Pearton, Fan Ren
Summary: There are various applications for deep UV AlGaN Light-Emitting Diodes (LEDs), including virus inactivation, air and water purification, sterilization, bioagent detection, and UV polymer curing. The long-term stability of these LEDs is important for space missions such as the Laser Interferometer Space Antenna (LISA). The literature review shows that the decline in output power of these LEDs over extended operating times is mainly driven by current and temperature, with the degradation rate dependent on the cube of drive current density and exponentially on temperature. The main mechanism for this decline is believed to be the creation/migration of point defects. Pre-screening based on the ratio of band edge-to-midgap emission and LED ideality factor can identify devices with long lifetimes (>10,000 h).
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(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
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)
