Article
Optics
Yiwei Cao, Quanjiang Lv, Tianpeng Yang, Tingting Mi, Xiaowen Wang, Wei Liu, Junlin Liu
Summary: High-efficiency 278 nm AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) with a bidirectional-staircase-barrier (BSB) structure were studied. The experimental results showed that the proposed BSB structure achieved a maximum external quantum efficiency (EQE) of 8.47% and a wall-plug efficiency (WPE) of 7.01%. Compared to the reference structure, the EQE and WPE were improved by 32% and 31%, respectively. Numerical simulations demonstrated that the BSB structure enhanced electron confinement, improved hole injection, and increased hole concentration in the active region by 170%. The BSB structure also improved the radiative recombination rate and quantum efficiency of the DUV-LEDs.
JOURNAL OF LUMINESCENCE
(2023)
Article
Optics
Lei Han, Yuanbin Gao, Sheng Hang, Chunshuang Chu, Yonghui Zhang, Quan Zheng, Qing Li, Zi-Hui Zhan
Summary: This work proposes GaN-based VCSELs with the p-AlGaN/p-GaN structure to enhance the laser power. The p-AlGaN/p-GaN heterojunction can store electric field and adjust the drift velocity and kinetic energy of holes, improving the thermionic emission process. Additionally, by using the p-AlGaN layer, the valence band barrier height in the p-EBL can be reduced, leading to better stimulated radiative recombination rate and increased laser power.
CHINESE OPTICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Mengran Liu, Wentao Tian, Chao Liu
Summary: Insufficient hole injection and current nonuniformity caused by the p-AlGaN hole injection layer are addressed by proposing an Al-linearly-decreasing AlGaN PN junction to replace the conventional p-AlGaN HIL with a constant Al component. The proposed structure enhances hole injection efficiency and improves current uniformity by modulating the barrier height and resistance in the p-AlGaN HIL. The DUV LED with the proposed ALD AlGaN PN junction structure achieves enhanced EQE and improved current uniformity, showing promise for high-performance DUV LEDs.
OPTICAL MATERIALS EXPRESS
(2023)
Article
Materials Science, Multidisciplinary
Fan Xia, Huiqing Sun, Zhibin Liu, Xiaoyu Xia, Xiuyang Tan, Jiancheng Ma, Miao Zhang, Zhiyou Guo
Summary: A comprehensive study on an E-mode AlGaN/GaN MIS-HEMT with triple barrier layer was conducted using Silvaco TCAD software, investigating the impact of geometric parameters on device performance. The optimized device showed improved characteristics, such as high threshold voltage, large maximum drain current, and gate-source capacitance at 1 MHz frequency. The analysis of different combinations of triple structural parameters led to two types suitable for specific conditions, aiding in enhancing the DC and RF characteristics of E-mode AlGaN/GaN MIS-HEMT.
RESULTS IN PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Taofei Pu, Hsiang-Chun Wang, Kuang-Po Hsueh, Hsien-Chin Chiu, Xinke Liu
Summary: This paper presents the fabrication of AlGaN/GaN Schottky barrier diodes (SBDs) on free-standing GaN substrates with a Si doped barrier layer. The SBDs with doped barrier layer exhibit lower turn-on voltage, specific on resistance, faster reverse recovery time, and better low-frequency noise characteristics, which make them suitable for high power applications.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2022)
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
Engineering, Electrical & Electronic
Tao Zhang, Yueguang Lv, Ruohan Li, Yanni Zhang, Yachao Zhang, Xiangdong Li, Jincheng Zhang, Yue Hao
Summary: This letter demonstrates a high-performance lateral AIGaN/GaN Schottky barrier diode featuring low turn-on voltage and high breakdown voltage, achieved by using a low work-function tungsten layer and a thick GaN cap layer. The device shows impressive stability in dynamic on-resistance and turn-on voltage under long-duration stress tests, indicating great potential for next-generation power electronic devices.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Physics, Applied
Saulius Marcinkevicius, Jacob Ewing, Rinat Yapparov, Feng Wu, Shuji Nakamura, James S. Speck
Summary: Hole injection through V-defect sidewalls into all quantum wells can increase the efficiency of long wavelength GaN light emitting diodes, allowing for population of all wells in a multiple QW structure.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Chia-Hao Liu, Hsien-Chin Chiu, Hsiang-Chun Wang, Hsuan-Ling Kao, Chong-Rong Huang
Summary: The study shows that DJ-HEMT exhibits higher gate voltage swing in the gate region due to the dual junction, enhancing gate performance. Compared to ST-HEMT, DJ-HEMT has higher V-TH, saturation current, I-ON/I-OFF ratio, and gate swing voltage. In addition, DJ-HEMT also has lower leakage current and longer lifetime measurement.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Physics, Applied
Peng Du, Lang Shi, Sheng Liu, Shengjun Zhou
Summary: Numerical simulation shows that utilizing InAlGaN/AlGaN electron blocking layer can improve the performance of deep ultraviolet LED, especially when optimizing the In composition. Replacing it with InAlGaN/AlGaN superlattice EBL further enhances the performance.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Joseph Pinchbeck, Kean Boon Lee, Sheng Jiang, Peter Houston
Summary: AlGaN/GaN high electron mobility transistors with a variety of dual metal gate (DMG) lengths were fabricated and studied, showing an improvement in transconductance up to 9% compared to conventional single metal gate devices. The use of sub-micron DMG devices can also suppress drain induced barrier lowering by around 50% due to a potential shielding effect in the two-dimensional electron gas channel.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2021)
Article
Physics, Condensed Matter
Haiyong Wang, Wei Mao, Shenglei Zhao, Jiabo Chen, Ming Du, Xuefeng Zheng, Chong Wang, Chunfu Zhang, Jincheng Zhang, Yue Hao
Summary: The p-GaN RB-HEMT, featuring a p-GaN layer embedded in the ohmic drain, achieves reverse blocking capability and effectively suppresses reverse leakage current, leading to ultralow reverse leakage current and high reverse breakdown voltage. Moreover, the device exhibits a positive threshold voltage, forward breakdown voltage, and linear relationship between Von, Ron, and p-GaN drain dimension.
SUPERLATTICES AND MICROSTRUCTURES
(2021)
Article
Biochemistry & Molecular Biology
Chong-Rong Huang, Hsien-Chin Chiu, Chia-Hao Liu, Hsiang-Chun Wang, Hsuan-Ling Kao, Chih-Tien Chen, Kuo-Jen Chang
Summary: In this study, an AlGaN/GaN HEMT grown on Qromis Substrate Technology (QST) showed superior heat dissipation performance compared to one grown on a Si substrate due to the higher thermal conductivity of the QST substrate. Thermal imaging analysis revealed that the GaN on the QST device had a temperature variation of 4.5 degrees C, while the GaN on the Si device had a temperature variation of 9.2 degrees C at a drain-to-source current of 300 mA/mm after 50 seconds of operation. Additionally, the GaN on the QST device exhibited lower degradation of drain-to-source current at high temperatures (17.5% at 400 K) compared to the GaN HEMT on the Si device.
Article
Materials Science, Ceramics
Kai Chen, Yachao Zhang, Jincheng Zhang, Xing Wang, Yixin Yao, Jinbang Ma, Yue Hao
Summary: By analyzing the growth modes of GaN films on AlN buffer layers with different thicknesses, a new growth model of GaN on AlN buffer was proposed in this study. Under optimal conditions, AlGaN/GaN/AlN heterostructures showed excellent performance.
CERAMICS INTERNATIONAL
(2022)
Article
Physics, Condensed Matter
Cong Zhang, Ruohe Yao
Summary: An AlInN/GaN high electron mobility transistors (HEMTs) is designed to deplete the two-dimensional electron gas (2DEG) under the gate by using the polarization modulation effect of the GaN cap layer and the AlGaN back barrier layer. The thin AlInN barrier layer can increase the gate control capability and improve the transconductance of the device, while the intrinsic GaN cap layer without doping reduces the complexity of fabrication.
SOLID STATE COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Kuo-Bin Hong, Lih-Ren Chen, Kuan-Chih Huang, Hsu-Tung Yen, Wei-Chih Weng, Bing-Hong Chuang, Tien-Chang Lu
Summary: In this study, the optical performances of 950 nm p-side up photonic crystal surface emitting lasers with different types of air holes were investigated numerically and experimentally. The simulation results showed a distinction between effective index method and three dimensional finite-element method (FEM). The experimental measurements were in good agreement with the FEM numerical predictions, revealing that the B mode dominated the laser action and PCSELs with equilateral triangle and right isosceles triangle holes exhibited better performance.
IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS
(2022)
Article
Optics
Yizhi Zhu, Heng Guo, Qiannan Cui, Jinping Chen, Zhuxin Li, Junfeng Lu, Tien-Chang Lu, Zhengchun Peng, Chunxiang Xu, Caofeng Pan
Summary: Manipulating photocarrier dynamics for luminescent materials is of fundamental importance for controlling the luminescent properties of optoelectronic devices. This study demonstrates the enhancement and prolongation of photoluminescence through interfacial engineering, which enables resonant coupling between localized surface plasmon and exciton. The photocarrier dynamics at the interface are mediated by plasmon-induced hot electron transfer (PHET) and plasmon-induced resonant energy transfer (PIRET) processes, which can be actively switched on and off by varying the excitation laser wavelength. These findings are highly significant for actively manipulating photocarrier dynamics in perovskite luminescent devices.
LASER & PHOTONICS REVIEWS
(2023)
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
Chemistry, Multidisciplinary
Zhen-Ting Huang, Ting-Wei Chien, Chang-Wei Cheng, Cheng-Ching Li, Kuo-Ping Chen, Shangjr Gwo, Tien-Chang Lu
Summary: Stable electrical modulation of plasmonic nano-lasers is achieved on a hybrid graphene-insulator-metal (GIM) platform at room temperature. A zinc oxide (ZnO) nanowire is placed on the GIM platform to create a plasmonic cavity, and the graphene layer is used for electrical modulation. The lasing thresholds of the ZnO nanowire plasmonic nanolasers on the GIM platform can be modulated by the gate voltage, demonstrating high potential for plasmonic circuit applications.
Article
Engineering, Electrical & Electronic
Chia-Yen Huang, Wen-Hsuan Hsieh, Teng-Li Shao, Chang-Hsien Wu, Tien-Chang Lu
Summary: We reported an unexpected power degradation mechanism in high-power UVC LEDs grown on high-quality AlN templates. Nitrogen desorption, activated by UVC photon emitted from the active region, introduced observable nitrogen loss and created a continuous leakage path from the active region to the p-electrode via various trap-assisted transport mechanisms, resulting in the power degradation of the LEDs.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Chemistry, Multidisciplinary
Jun-Wei Liao, Zhen-Ting Huang, Chia-Hung Wu, Nikita Gagrani, Hark Hoe Tan, Chennupati Jagadish, Kuo-Ping Chen, Tien-Chang Lu
Summary: In this study, localized surface plasmon lasing at room temperature in the communication band was achieved using metallic nanoholes as plasmonic nanocavity and InP nanowires as gain medium. Optimization of laser performance was demonstrated through coupling between two metallic nanoholes, allowing for manipulation of lasing properties. These plasmonic nanolasers offer lower power consumption, smaller mode volumes, and higher spontaneous emission coupling factors, making them promising for high-density sensing and photonic integrated circuits.
Article
Chemistry, Multidisciplinary
Lih-Ren Chen, Chia-Jui Chang, Yi-Jing Wu, Cheng-Lin Liu, Wei Lin, Tien-Chang Lu
Summary: This study presents research on InP-based photonic-crystal surface-emitting lasers (PCSELs) for high-power emission in the L band. The incorporation of embedded air voids within a 2D photonic crystal structure enables vertical laser emission. Investigation into the regrowth processes successfully retained the air holes and achieved an atomically flat p-type surface, resulting in higher output efficiency.
CRYSTAL GROWTH & DESIGN
(2023)
Article
Chemistry, Multidisciplinary
Chia-Hung Wu, Chih-Jen Ku, Min-Wen Yu, Jhen-Hong Yang, Pei-Yuan Wu, Chen-Bin Huang, Tien-Chang Lu, Jer-Shing Huang, Satoshi Ishii, Kuo-Ping Chen
Summary: This study explores plasmonic photodetection using graphene as a 2D material, achieving non-scattering near-field detection of surface plasmon polaritons. The maximum photoresponsivity is 29.2 mA W-1, and the polarization state of the input light produces a 400% contrast. This has potential applications in on-chip optoelectronic circuits.
Editorial Material
Optics
Jin-Wei Shi, Tien-Chang Lu, Fumio Koyama
Article
Materials Science, Multidisciplinary
Zuhaib Khan, Min-Long Wu, Cheng-Wei Lin, Cheng-Chun Chen, Chia-Jui Chang, Tien-Chang Lu, Nikolay Ledentsov Jr, Nikolay Ledentsov, Jin-Wei Shi
Summary: This article demonstrates a novel layout and arrangement of electrodes for a vertical-cavity surface-emitting laser (VCSEL) array, which improves both its high-speed data transmission performance and the brightness of the output beam. The new design reduces the pitch size between neighboring light emission apertures, allowing downsizing of the whole active area and achieving high brightness output. The demonstrated compact 7 x 7 VCSEL array features separate electrodes for dc current injection and ac signal modulation, leading to improved electrical-optical frequency response, wider bandwidth, and higher brightness output compared to a reference device.
ADVANCED PHOTONICS RESEARCH
(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
Nanoscience & Nanotechnology
Chia-Jui Chang, Yu-Wen Chen, Lih-Ren Chen, Kuo-Bin Hong, Jhih-Sheng Wu, Yao-Wei Huang, Tien-Chang Lu
Summary: This article introduces a new method for directly generating vector vortex beams from photonic crystal surface emitting lasers while preserving C-6 rotation symmetry. The ability to dynamically switch between different orders is demonstrated.
Article
Chemistry, Multidisciplinary
Zhen-Ting Huang, Ting-Wei Chien, Chang-Wei Cheng, Cheng-Ching Li, Kuo-Ping Chen, Shangjr Gwo, Tien-Chang Lu
Summary: Stable electrical modulation of plasmonic nanolasers is achieved on a graphene-insulator-metal platform, where the gate voltage can adjust the lasing thresholds of the ZnO nanowire plasmonic nanolasers, providing high-speed modulation characteristics.
Article
Nanoscience & Nanotechnology
Chia-Jui Chang, Lih-Ren Chen, Kuo-Bin Hong, Tien-Chang Lu
Summary: Photonic crystal surface-emitting lasers (PCSELs) have promising properties over traditional semiconductor lasers. However, the minimum achievable lasing threshold of PCSELs is still larger than that of vertical-cavity surface-emitting lasers (VCSELs), limiting its applications. In this study, a new design is proposed to reduce the threshold current of PCSELs by using selective quantum-well intermixing, while maintaining the advantage of small divergence angle.
Article
Chemistry, Physical
Min-Wen Yu, Yu-Tang Lin, Chia-Hung Wu, Tung-Jung Wang, Jhuang-Hao Cyue, Jun Kikkawa, Satoshi Ishii, Tien-Chang Lu, Kuo-Ping Chen
Summary: This work successfully controlled the number of sulfur vacancies in monolayer WS2 flakes synthesized by chemical vapor deposition (CVD), resulting in a difference in photoluminescence (PL) intensity. The sulfur vacancies introduce defect trap states that cause carrier recombination and reduce carrier drift to graphene, thus decreasing the photocurrent. Furthermore, the gate-tunable Fermi level of graphene allows tunable responsivity of the WS2-graphene photodetector.
APPLIED SURFACE SCIENCE
(2024)
