學術出版;;Publications

Permanent URI for this communityhdl:11536/1

收集所有交通大學研究人員與學生個人或團體所發表之各項學術著作，涵蓋期刊論文、教師專書、學位論文等項。;;Collections of Publications of NCTU Researchers and Students Like Journal Papers and Thesis.

Browse

🏛️國立陽明交通大學機構典藏

Search Results

Now showing 1 - 10 of 37

Process Integration and Interconnection Design of Passive-Matrix LED Micro-Displays With 256 Pixel-Per-Inch Resolution
(2020-01-01)
Yuan, Shuo-Huang
;
Yan, Shih-Siang
;
Yao, Yu-Shiuan
;
Wu, Chung-Cheng
;
Horng, Ray-Hua
A 0.28-inch InGaN-based blue micro-LED display with 256 pixel-per-inch resolution and a pitch of $100 mu m was successfully fabricated in this study. A thick Ti/Al/Ti/Au interconnection metal was deposited on the n-type gallium nitride (n-GaN) region to reduce the interconnection resistance. The micro-LED array with interconnection metal exhibits better electrical property consistency as compared with that of the traditional one. The output power, forward voltage, and external quantum efficiency of micro-LED, which measured under 1-mA current injection with the full lighting mode, are 0.8 mW, 3.0 V, and 10%, respectively. This technique has the potential to integrate InGaN-based LEDs with quantum dots for full-color applications.
Low resistive InGaN film grown by metalorganic chemical vapor deposition
(2020-01-01)
Shrestha, Niraj Man
;
Chauhan, Prerna
;
Wong, Yuen-Yee
;
Li, Yiming
;
Samukawa, Seiji
Indium gallium nitride (InGaN) samples were grown on sapphire substrate with low temperature GaN buffer by metalorganic chemical vapor deposition (MOCVD) under varying growth conditions, such as temperature, pressure and ammonia flow. Although high indium composition is considered as indispensable parameter for sheet carrier concentration (n(s)) and low sheet resistance (R-s), our outcomes disclose that higher indium composition in InGaN film doesn't always have high n(s) and low R-s. Acceptor nature of carbon related defects, a major trapping sites for electrons, plays a crucial role to limit the carrier concentrations in the InGaN specially grown at low pressure, low temperature and low ammonia flow. Furthermore, study of metal contacts deposited on the grown samples by transmission line method (TLM) shows that carrier concentration is the most important factor to obtain low contact resistance. The measured contact resistance for the sample with 4.5x 10(16) cm(2) carrier concentration is 0.13 Omm which is among the lowest contact resistance for GaN based materials grown by MOCVD. This proves that the use of InGaN in source and drain contact region can surpassingly reduce contact resistance and significantly improve device performance of AlGaN/GaN device.
Analysis of Quality Factor Enhancement in the Monolithic InGaN/GaN Nanorod Array
(2019-04-01)
Huang, Chia-Yen
;
Tai, Tzu-Ying
;
Hong, Kuo-Bin
;
Kuo, Hao-Chung
;
Lu, Tien-Chang
Whispering gallery mode (WGM) lasers and resonators are key building blocks for photonic integrated circuits. The quality factor and resonant wavelength are strong functions of the cavity size. Nanoscale WGM cavities suffer from a low-quality factor due to prominent scattering loss. However, the quality factor could be enhanced by forming an optically-coupled rod array or photonic molecules. Through simulations, we revealed how rod-to-rod optical coupling influenced the threshold pumping level and dominant mode selection, where the trend showed good agreement with the experimental observation. According to the simulation, the quality factor could be enhanced by up to eight times by forming a six-rod photonic molecule. The quality factor and effective mode were both superior to the single rods with the same wafer device footprint.
Design and Fabrication of the Reliable GaN Based Vertical-Cavity Surface-Emitting Laser via Tunnel Junction
(2019-04-01)
Shen, Chih-Chiang
;
Lu, Yun-Ting
;
Yeh, Yen-Wei
;
Chen, Cheng-Yuan
;
Chen, Yu-Tzu
In this study, we theoretically designed and experimentally fabricated an InGaN vertical-cavity surface-emitting laser (VCSEL) with a tunnel junction (TJ) structure. From numerical simulation results, the optical loss of the device can be reduced by a TJ structure. Additionally, the leakage current of the VCSEL with TJ structure was much smaller than that of the VCSEL with an Indium-Tin-Oxide (ITO) layer. We have been demonstrated that laser output performance is improved by using the TJ structure when compared to the typical VCSEL structure of the ITO layer. The output power obtained at 2.1 mW was enhanced by a factor of 3.5 by the successful reduction of threshold current density (J(th)) from 12 to 8.5 kA/cm(2), and the enlarged slope efficiency was due to less absorption in VCSEL with a TJ structure. Finally, the samples passed the high temperature (70 degrees C) and high operation current (1.5 x J(th)) test for over 500 h.
Abnormal PL spectrum in InGaN MQW surface emitting cavity
(2008-01-01)
Chu, J. T.
;
Cheng, Y. -J.
;
Kuo, H. C.
;
Lu, T. C.
;
Wang, S. C.
We report the observation of an abnormal photoluminescent (PL) spectrum from a HeCd laser pumped InGaN multiple quantum well (MQW) vertical cavity. The device is fabricated using standard MOCVD deposition on a (0001)-oriented sapphire substrate. The layer structures are: 10nm nucleation layer, a 4um bulk GaN layer, InGaN MQWs, and a final 200nm GaN cap layer. The InGaN MQWs consist of 10 pairs of 5 nm GaN barrier and 3 run In0.1Ga0.9N well. The peak emission of the as-grown MQWs sample was similar to 420nm. A dielectric distributed Bragg reflectors (DBR) were then coated on the top layer, followed by a laser lift off from sapphire substrate, and subsequently another DBR coated on the bulk GaN bottom surface. The cavity has a quality factor of similar to 520 from 400-490nm. The device was pumped by a focused CW HeCd laser from the bulk GaN side. When the laser is focused onto the InGaN MQWs, a photoluminescent spectrum centered at the designed MOW wavelength was observed as expected. However, when the focused position was moved toward the bulk GaN region, an additional abnormal PL peak around 460nm was observed. This is far outside the designed MQW wavelength.
Analysis of Strain Relaxation and Emission Spectrum of A Free-Standing GaN-based Nanopillar
(2008-01-01)
Wu, Yuh-Renn
;
Yu, Peichen
;
Chiu, C. H.
;
Chang, Cheng-Yu
;
Kuo, H. C.
We have made a, GaN-based single nanopillar with a, diameter of 300nm using the focused ion beam (FB) technique. The micro-photoluminescence (mu-PL) from the embedded GaN/InGaN multi-quantum wells reveals a blue shift of 68.3 meV in energy. In order to explain the spectrum shift, we have developed a valence force field model to study the strain relaxation mechanism in a, single GaN-based nanopillar structure. The strain distribution and strain induced polarization effect inside the multiple quantum wells is added to our self-consistent Poisson, drift-diffusion, and Schrodinger solver to study the spectrum shift of mu-PL.
Quantum dot vertical-cavity surface-emitting lasers covering the 'green gap'
(2017-01-01)
Mei, Yang
;
Weng, Guo-En
;
Zhang, Bao-Ping
;
Liu, Jian-Ping
;
Hofmann, Werner
Semiconductor vertical-cavity surface-emitting lasers (VCSELs) with wavelengths from 491.8 to 565.7 nm, covering most of the 'green gap', are demonstrated. For these lasers, the same quantum dot (QD) active region was used, whereas the wavelength was controlled by adjusting the cavity length, which is difficult for edge-emitting lasers. Compared with reports in the literature for green VCSELs, our lasers have set a few world records for the lowest threshold, longest wavelength and continuous-wave (CW) lasing at room temperature. The nanoscale QDs contribute dominantly to the low threshold. The emitting wavelength depends on the electron-photon interaction or the coupling between the active layer and the optical field, which is modulated by the cavity length. The green VCSELs exhibit a low-thermal resistance of 915 kW(-1), which benefits the CW lasing. Such VCSELs are important for small-size, low power consumption full-color displays and projectors.
Mode-Hopping Phenomena in the InGaN-Based Core-Shell Nanorod Array Collective Lasing
(2018-07-01)
Huang, Chia-Yen
;
Tai, Tzu-Ying
;
Lin, Jing-Jie
;
Chang, Tsu-Chi
;
Liu, Che-Yu
A two-dimensional monolithic InGaN-based core-shell it array was excited under a varying temperature. We observed an abrupt dominant mode hopping from 3.29 to 141 eV in the collective lasing as the temperature decreased from T = 240 to 225 K, Photoluminescence under a near-threshold pumping density revealed the splitting of spontaneous emission. between the core and the shell with a decreasing temperature. The bandgap evolution of GaN and InGaN showed opposite trends due to the interaction of temperature effects and bandgap renormalization effects. Theoretical simulation revealed the differences of gain spectra evolution between room lire and to temperature due to the difference the carrier dynamics, In the optically coupled nanorod array, the dominant lasing;mode was not only determined by it structure, but also strongly influenced by external operating conditions. Rattier than singular microcavity lasers the coupled nanorod array demonstrated a broader parameter space for on-chip wavelength manipulation.
Discussion on electrical characteristics of i-In0.13Ga0.87N p-i-n photovoltaics by using a single/multi-antireflection layer
(2010-07-01)
Lee, Han Cheng
;
Su, Yan Kuin
;
Chuang, Wen Kuei
;
Lin, Jia Ching
;
Huang, Kuo Chin
Active layers of i-In0.13Ga0.87N p-i-n photovoltaics (PVs) with a single antireflection layer (SARL) and a multi-antireflection layer (MARL), respectively, were fabricated. Reflectance simulation results show that the PVs with a SARL or a MARL have performance superior to those without an antireflection layer (ARL). In particular, the surface reflectance of PVs with a MARL was reduced to 6% at wavelengths between 330 and 500 nm. The ARL reduced the reflectance and recombination current, as well as boosting shunt resistance without increasing series resistance. Compared with PVs without an ARL, the open-circuit voltage and fill factor of PVs with a MARL increased by 100% and 54.5%, respectively. The ideal factor was improved by 19.4% and 31.9% in devices with a SARL (SiO2) and a MARL (Ta2O5/SiO2), respectively. (C) 2010 Elsevier B.V. All rights reserved.
Efficiency Enhancement in InGaN Photovoltaic Cells With Inverted Textured Surface
(2017-08-15)
Wu, Ming-Hsien
;
Horng, Ray-Hua
;
Liao, Wen-Yih
;
Chang, Sheng-Po
;
Chang, Shoou-Jinn
We report on the improvement of conversion efficiency of InGaN photovoltaic (PV) cells with inverted textured surface (ITS). InGaN PV cells with ITS showed short-circuit current density and conversion efficiency of 0.63 mA/cm(2) and 1.01%, which are 68.17% and 73.33% higher than the characteristics of conventional InGaN PV cells, respectively. The improvement can be attributed to the reduction of both the shading effect of the electrode contact pad and surface reflection of the incident irradiation under one-sun air-mass 1.5-G illumination (100 mW/cm(2)).

學術出版;;Publications

Browse

Filters

Settings

Sort By

Results per page

🏛️國立陽明交通大學機構典藏

Search Results