Article
Engineering, Electrical & Electronic
Yi Lu, Chuanju Wang, Victor Paiva De Oliveira, Zhiyuan Liu, Xiaohang Li
Summary: The study demonstrates the importance of inverse design of n-type and p-type layers in generating opposite polarization-induced fields to suppress electron overflow and enhance hole injection in III-nitride UV LEDs. By utilizing a buried tunneling junction (BTJ) composed of n-AlGaN/i-InGaN/p-AlGaN, significant enhancement in LED output power can be achieved through optimizing the composition and thickness of the InGaN tunneling layer.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2021)
Article
Physics, Condensed Matter
Muhammad Nawaz Sharif, Mussaab Ibrahim Niass, Juin J. Liou, Fang Wang, Yuhuai Liu
Summary: By utilizing a new AlInN-based electron blocking layer (EBL), the optoelectronic characteristics of AlGaN-based deep-ultraviolet LED can be improved, with enhanced hole injection, reduced electron overflow, and lower electric field. Additionally, employing an AlInN/AlInN superlattice EBL structure can further enhance carrier distribution and reduce electric field for higher electron-hole wavefunction overlap.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Crystallography
Yi-Tsung Chang, Mu-Jen Lai, Rui-Sen Liu, Shu-Chang Wang, Xiong Zhang, Lin-Jun Zhang, Yu-Hsien Lin, Shiang-Fu Huang, Lung-Chien Chen, Ray-Ming Lin
Summary: This study found that the current droop in AlGaN-based UVB light-emitting diodes is more noticeable at higher temperatures, despite both the main and parasitic peaks decreasing in intensity with increasing temperature. However, the slower temperature droop does not occur when the forward current is increased to temperatures above 298 K. After a 6000-hour aging period, the emission wavelengths do not show obvious changes, while the intensity of the parasitic peak remains nearly unchanged. Therefore, the degradation in light output power during long-term operation is not significantly correlated to the presence of the parasitic peak.
Article
Optics
Yuan Xu, Mengshuang Yin, Xien Sang, Fang Wang, Juin J. Liou, Yuhuai Liu
Summary: In this paper, we significantly improved the internal quantum efficiency and the output power of AlGaN-based deep UV (DUV) LEDs by replacing the conventional p-AlGaN electron blocking layer (EBL) with the p-AlInGaN/AlInGaN graded superlattice (SL) EBL. The simulation results demonstrated that the introduction of the p-AlInGaN graded SL EBL improved the carrier distribution and increased the radiative recombination rate in the multiple quantum wells (MQWs). The proposed p-AlInGaN graded SL EBL achieved a highest IQE of 96.6%, which was 44.9% higher than the conventional p-AlGaN EBL with no efficiency droop. Meanwhile, the output power was 4.6 times higher than that of the conventional p-AlGaN EBL. The proposed p-AlInGaN graded SL EBL is expected to be beneficial for the development of high-performance DUV LEDs.
Article
Materials Science, Multidisciplinary
Zhenzhuo Zhang, Jing Yang, Feng Liang, Yufei Hou, Zongshun Liu, Degang Zhao
Summary: In this paper, a method to reduce the tensile stress during AlGaN growth by inserting an InGaN interlayer is proposed. The validity of this method was verified by insitu curvature monitor, reciprocal space mapping and temperature-dependent Raman spectral observation. It is found that the insertion of InGaN interlayer introduces V-shaped pits into the AlGaN structure which can play a role in stress release.
RESULTS IN PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Chunshuang Chu, Danyang Zhang, Hua Shao, Jiamang Che, Kangkai Tian, Yonghui Zhang, Zi-Hui Zhang
Summary: This work presents an AlGaN-based deep ultraviolet light-emitting diode with increased Al composition to enhance electron and hole injection efficiency, resulting in increased optical power and reduced forward voltage compared to conventional DUV LEDs.
OPTICAL MATERIALS EXPRESS
(2021)
Article
Optics
Chuanyu Jia, Chenguang He, Qi Wang, Zhizhong Chen
Summary: Experimental and theoretical analysis of u-AlGaN/InGaN superlattices (SLs) last quantum barrier (LQB) and p-AlGaN/InGaN SLs electron blocking layer (EBL) on the performance of InGaN light-emitting diodes (LEDs) reveal that using such structure can significantly enhance the output power and efficiency of LEDs, effectively suppressing efficiency droop.
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
Optics
Longheng Qi, Peian Li, Xu Zhang, Ka Ming Wong, Kei May Lau
Summary: A prototype of full-color micro-LED micro-display with a pixel density of 391 ppi is demonstrated using InGaN/AlGaInP heterogeneous integration. This display shows the feasibility and prospects of high brightness, good color performance, and high-resolution micro-LED micro-displays in future metaverse applications.
LIGHT-SCIENCE & APPLICATIONS
(2023)
Article
Optics
Hyun Jeong, Ga Hyun Cho, Mun Seok Jeong
Summary: We propose an efficient method to reduce efficiency droop in InGaN QWs by redistributing carrier localization through thermal annealing, resulting in increased internal quantum efficiency (IQE) in this study.
JOURNAL OF LUMINESCENCE
(2022)
Article
Physics, Applied
A. Pandey, J. Gim, R. Hovden, Z. Mi
Summary: The study found that AlGaN deep UV LEDs can achieve higher efficiency by using a tunnel junction and a polarization-engineered AlGaN electron blocking layer, but severe efficiency droop was observed at very low current densities, with the primary limiting factors being issues related to TM polarized emission.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Analytical
Barsha Jain, Ravi Teja Velpula, Moulik Patel, Sharif Md. Sadaf, Hieu Pham Trung Nguyen
Summary: The study introduces an EBL-free AlGaN deep UV LED structure with graded staircase quantum barriers to reduce electron leakage and efficiency droop. This structure improves electron confinement, reduces the quantum-confined Stark effect, and enhances electron and hole wavefunctions overlap, leading to significantly higher internal quantum efficiency and output power compared to conventional structures.
Article
Materials Science, Multidisciplinary
Chaozhi Xu, Lie Cai, Jinjian Zheng, Haoxiang Lin, Zhichao Chen, Kai Niu, Zaijun Cheng, Feibing Xiong
Summary: In this paper, the effect of layer thickness on the light-electric performance of a near-ultraviolet LED with an undoped AlGaN insertion layer was investigated. The results show that an insertion layer thickness of 1 nm achieves the optimal light emission performance for the LED.
RESULTS IN PHYSICS
(2023)
Article
Optics
Ravi Teja Velpula, Barsha Jain, Moulik Patel, Fatemeh Mohammadi Shakiba, Ngo Quoc Toan, Hoang-Duy Nguyen, Hieu Pham Trung Nguyen
Summary: This study mitigates the effect of positive sheet polarization charges in III-nitride light-emitting diodes by employing a lattice matched last QB, effectively reducing electron leakage and promoting hole injection.
Article
Optics
Yi Zhang, Shuang Zhang, Linlin Xu, Huixue Zhang, Ange Wang, Maocheng Shan, Zhihua Zheng, Hao Wang, Feng Wu, Jiangnan Dai, Changqing Chen
Summary: The study found that the LOP and peak wavelength of DUV LED chips are related to the quantum well thickness and warpage, while the EQE and yield can be improved by increasing the quantum well thickness. These findings help to enhance the efficiency of DUV LEDs and provide new insights for evaluating the performance of DUVLED wafers.
Article
Engineering, Electrical & Electronic
Shu-Bai Liu, Chia-Hsun Chen, Sheng-Po Chang, Chen-Hao Li, Shoou-Jinn Chang
Summary: By adjusting the co-sputtering power ratio and annealing process, AlGaZnO photodetectors exhibited excellent response characteristics under UV illumination, with improved on/off ratio and responsivity. The results suggest that AGZO photodetectors have good performance and can be a promising candidate for solar-blind applications at low cost.
IEEE SENSORS JOURNAL
(2021)
Article
Materials Science, Multidisciplinary
Sheng-Po Chang, Wei-Lun Huang, Liang-Wei Huang, Sheng-Ying Pan, Wei-Chih Lai, Shoou-Jinn Chang
Summary: By inserting Al0.05Ga0.95O and In0.9Ga0.1O layers into the resistance-switching layer of the RRAM cell, the on/off ratio can be increased and the reset voltage can be reduced, effectively reducing power consumption.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Sheng-Po Chang, Wei-Lun Huang, Po-Ju Wu
Summary: The research showed that the homojunction structure of In2O3/InWO interface improved device performance, while the transparent S/D electrodes magnified the light-sensing area, significantly enhancing the responsivity of the phototransistor.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Chia-Hsun Chen, Shu-Bai Liu, Sheng-Po Chang
Summary: In this study, In0.9Ga0.1O sensing membrane was deposited using RF magnetron sputtering at room temperature and combined with commercial MOSFETs to create EGFET pH sensors. The sensors exhibited good linearity and sensitivity in the pH range of 2 to 12, making them a promising option for pH sensing applications.
Article
Materials Science, Multidisciplinary
Jia-Cheng Jian, Yu-Chi Chang, Sheng-Po Chang, Shoou-Jinn Chang
Summary: A novel gas sensor device based on apple pectin film doped with NiO was fabricated for the first time using a solution processing technique and annealed in a microwave chamber. The device showed superior sensing performance towards ethanol gas compared to pure apple pectin film sensor, with a response time of 1.379 s at an operational temperature of 250 degrees C for a 10 ppm concentration of ethanol gas. The sensing mechanism for the sensor device was also described thoroughly.
Article
Materials Science, Multidisciplinary
Sheng-Po Chang, Ren-Hao Yang, Chih-Hung Lin
Summary: InTiZnO gas sensors fabricated by RF sputtering at different oxygen ratios exhibited high sensing responses, selectivity, and repeatability for various gases. UV light activation reduced the operating temperature without damaging the sensing film, showing long-term stability and potential for gas sensing technology.
Article
Engineering, Chemical
Tien-Yu Wang, Wei-Chih Lai, Syuan-Yu Sie, Sheng-Po Chang, Cheng-Huang Kuo, Jinn-Kong Sheu
Summary: The introduction of p-AlGaN/AlGaN superlattice (SL) hole injection structure can enhance the performance of deep ultraviolet (DUV) light-emitting diodes (LEDs), resulting in reduced forward voltage and improved light output power.
Article
Materials Science, Multidisciplinary
Chih-Chiang Yang, Yun-Ting Tsai, Hao-Lin Hsu, Sheng-Po Chang, Yan-Kuin Su
Summary: Electronics based on natural materials have the advantages of simple preparation procedures, low cost, ecofriendliness, and biocompatibility. In this study, a silver-doped citrus pectin material was synthesized, and a RRAM device was fabricated using a simple fabrication method. The results showed that the 10% silver-doped device exhibited excellent stability and reliability, and could achieve multilevel storage in a single device.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Yong-Tang Zeng, Zhan-Rong Li, Sheng-Po Chang, Arjun Ansay, Zi-Hao Wang, Chun-Yuan Huang
Summary: This study demonstrates a facile synthesis method for highly luminescent Zn-doped CsPbBr3 perovskite nanocrystals. The doping of Zn significantly enhances the photoluminescence quantum yield, spectral properties, and stability of the nanocrystals, making them a promising candidate for practical optoelectronic devices.
Article
Chemistry, Multidisciplinary
Tien-Yu Wang, Wei-Chih Lai, Syuan-Yu Sie, Sheng-Po Chang, Cheng-Huang Kuo, Jinn-Kong Sheu, Jong-Shing Bow
Summary: AlGaN and GaN sidewalls were thermally oxidized to improve the optoelectronic characteristics of deep ultraviolet LEDs. The thermally oxidized AlxGa2-xO3 sidewall significantly enhanced light extraction efficiency and increased the light output power.
Article
Engineering, Electrical & Electronic
Shu-Bai Liu, Chia-Hsun Chen, Sheng-Po Chang, Chen-Hao Li, Shoou-Jinn Chang
Summary: In this study, extended gate field-effect transistor (EGFET) pH sensors with aluminum-gallium-zinc-oxide (AGZO) sensing film were fabricated using radio frequency (RF) cosputtering method. The pH sensitivity of the sensors was found to increase with the AGO:ZnO power ratio, reaching the highest value at AGO:ZnO ratio of 80W:50W. Furthermore, it was observed that the carrier transport improved by ZnO and the increased surface roughness contributed to the enhanced pH sensitivity.
IEEE SENSORS JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Yu-Neng Kao, Wei-Lun Huang, Sheng-Po Chang, Wei-Chih Lai, Shoou-Jinn Chang
Summary: Different oxygen partial-pressure MgGa2O4-resistive RAMs (RRAMs) were investigated for their resistive switching behaviors. By changing the fabrication conditions of the RS layer, the resistive switching characteristics of MgGa2O4 RRAM were significantly improved. A filament model was used to explain the mechanism of conductive filament generation and rupture. The high resistance state (HRS) was explained by the formation of the interfacial layer (AlOx) and the Joule heating effect. The low resistance state (LRS) and HRS corresponded to ohmic conduction and space charge-limited conduction, respectively. The optimized fabrication parameters of Al/MgGa2O4/Pt RRAM showed favorable cycling endurance and retention time, making them suitable for nonvolatile memristors and information security applications.
Article
Engineering, Electrical & Electronic
Jia-Cheng Jian, Yu-Chi Chang, Deng-Kai Chang, Sheng-Po Chang, Shoou-Jinn Chang
Summary: In this study, spherical-like ZnO UV photodetectors were synthesized using a facile hydrothermal method in the presence of different concentrations of apple pectin as a biotemplate. The addition of apple pectin not only modified the surface morphology but also improved the absorption properties and reduced the dark current. The best performance was achieved with the addition of 150 mg of apple pectin, exhibiting a high UV-to-dark current ratio and fast response and recovery times.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Chemistry, Multidisciplinary
Tien-Yu Wang, Wei-Chih Lai, Qiao-Ju Xie, Shun-Hao Yang, Sheng-Po Chang, Cheng-Huang Kuo, Jinn-Kong Sheu
Summary: The growth conditions of the AlGaN barrier in AlGaN/AlGaN deep ultra-violet (DUV) multiple quantum wells (MQWs) play a crucial role in the light output power of DUV light-emitting diodes (LEDs). Reducing the growth rate of the AlGaN barrier improves the quality of AlGaN/AlGaN MQWs, including surface roughness and defects. The light output power can be enhanced by up to 83% by lowering the growth rate from 900 nm h(-1) to 200 nm h(-1). Additionally, the altered growth rate affects the far-field emission patterns and polarization degree of the DUV LEDs, indicating a modification in the strain of the AlGaN/AlGaN MQWs.
Article
Engineering, Electrical & Electronic
Wei-Han Chen, Chun-Hao Ma, Shang-Hsien Hsieh, Yu-Hong Lai, Yen-Chien Kuo, Chia-Hao Chen, Sheng-Po Chang, Shoou-Jinn Chang, Ray-Hua Horng, Ying-Hao Chu
Summary: Transparent flexible deep-UV detectors based on high-quality epitaxial films on a flexible substrate have been developed in this study. The detectors show superior performance in terms of electrical current, response time, thermal stability, and mechanical flexibility.
ACS APPLIED ELECTRONIC MATERIALS
(2022)
