Browsing by Author "Huang, Yu-Jen"

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A study of phase transition behaviors of chalcogenide layers using in situ alternative-current impedance spectroscopy
(2012-06-15)
Huang, Yin-Hsien
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Huang, Yu-Jen
;
Hsieh, Tsung-Eong
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材料科學與工程學系
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Department of Materials Science and Engineering
Electrical properties of chalcogenide thin films, both pristine Ge2Sb2Te5 (GST) and cerium-doped GST, were investigated by in situ alternative-current (AC) impedance spectroscopy. With the aid of brick-layer model and nano-grain composite model, the roles of grain and grain-boundary on the phase transition of chalcogenides were distinguished and the dominance of grain boundary was observed. Tangent loss behaviors deduced by impedance analysis revealed alien-element doping alters the interfacial polarization and delays the phase-transition rate of GST. Analytical results also illustrated that the in situ AC impedance spectroscopy can be an alternative tool for characterizing the phase-change kinetics of chalcogenides thin films with nano-scale grain sizes. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729528]
Air Stable Ambipolar Organic Field-Effect Transistors and Complementary-Like Inverters Prepared with Surface-Modified Gate Dielectrics
(2009)
Chen, Fang-Chung
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Huang, Yu-Jen
;
光電工程學系
;
顯示科技研究所
;
Department of Photonics
Air stable ambipolar organic field-effect transistors containing p/n heterojunctions are achieved by passivating the electron trapping sites on the SiO(2) surface. The morphology of the heterojunctions is controlled by the film thicknesses of p- and n-channel semiconductors, thereby affecting the device air stability and the electrical characteristics. Further, air stable complementary-like inverters, which are able to work both in the first and the third quadrants with a high gain up to 30, are also demonstrated.
Characterizations and thermal stability improvement of phase-change memory device containing Ce-doped GeSbTe films
(2012-02-29)
Huang, Yu-Jen
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Tsai, Min-Chuan
;
Wang, Chiung-Hsin
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
Phase-transition temperature of GeSbTe (GST) chalcogenide film was drastically increased from 159 to 236 degrees C by cerium (Ce) doping (up to 8.6 at.%) without altering the resistivity property of GST. Grain refinement via the solid-solution mechanism and the amplification of p-type semiconducting behavior in Ce-doped GST were observed. They were correlated with the enhancement of thermal stability and data retention property of GST as revealed by exothermal and isothermal analyses. Phase-change memory (PCM) device characterized at various temperatures revealed an effective thermal stability improvement on the threshold voltage of PCM device by Ce doping. (c) 2011 Elsevier B.V. All rights reserved.
Characterizations of AgInSbTe and Its Nanocomposite Thin Films for Phase-Change Memory Applications
(2010)
Huang, Yu-Jen
;
Chung, Tzu-Chin
;
Wang, Chiung-Hsin
;
Hsieh, Tsung-Eong
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材料科學與工程學系
Phase transition kinetics and microstructures of AgInSbTe (AIST) and AIST-SiO(2) nanocomposite applied to phase-change memories (PCMs) are investigated. In situ electrical property measurement found that the incorporation of SiO(2) escalates the recrystallization temperature (T(x)) of nanocomposite. Both X-ray diffraction and transmission electron microscopy showed grain refinement in the nanocomposite which, in turn, results in an increase of the activation energy (E(a)) of phase transition, as indicated by subsequent Kissinger's analysis. Increase of T(x) and E(a) in the nanocomposite was ascribed to AIST grain refinement and hindrance to grain growth due to dispersed SiO(2) particles in the sample matrix. Johnson-Mehl-Avrami analysis revealed the decrease of Avrami exponent in nanocomposite, implying that the dispersed SiO(2) particles promote the heterogeneous phase transition. Static I-V characteristics and reversible binary switching behavior of PCM devices not only confirmed the results of microstructure characterizations but also illustrated the feasibility of the AIST and its nanocomposite layer for PCM fabrication. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3502531] All rights reserved.
Color filtering functional organic thin-film transistors
(2007)
Huang, Yu-Jen
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Chang, Hsiao-Fen
;
Tsai, Shu-Ting
;
Chuang, Chiao-Shun
;
Cheng, Jung-An
The colored insulators were utilized as the color filter and the dielectric layer of the OTFTs simultaneously to obtain the desired color. This work was successfully integrated gate insulator and color filter, which offered an ink-jet printing compatible process for cost-effective fabrication of liquid-crystal displays.
Comparative Study Between Extracavity and Intracavity Frequency-Doubled Laser at 532 nm: Application for the Deep Ultraviolet Generation at 266 nm
(2015-01-01)
Huang, Yu-Jen
;
Tang, Cheng-Yu
;
Cho, Chun-Yu
;
Su, Kuan-Wei
;
Chen, Yung-Fu
We construct a reliable actively Q-switched Nd:YVO4 laser to comparatively investigate the output performance of the second harmonic generation between the extracavity and intracavity configurations under a similar operated condition. It is experimentally found that the peak power at 532 nm obtained with the extracavity second harmonic generation is remarkably higher than that obtained with the intracavity configuration, even though the higher output power and larger pulse energy can be acquired with the intracavity second harmonic generation. We further perform the extracavity fourth harmonic generation to verify that the extracavity second harmonic generation is more advantageous in generating deep ultraviolet laser at 266 nm than the intracavity one, where the conversion efficiencies from 532 to 266 nm for each case are 37.1% and 7.2%, respectively. Moreover, under an incident pump power of 26 W at 808 nm and a pulse repetition rate of 40 kHz, the output power at 266 nm as high as 1.67 W is effectually generated with the combination of the extracavity second and fourth harmonic generations, corresponding to the conversion efficiency from 808 to 266 nm up to 6.4%.
Efficient Diode-Pumped Solid-State Laser At 266 nm
(2013)
Tang, Cheng-Yu
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Huang, Yu-Jen
;
Su, Kuan-Wei
;
Chen, Yung-Fu
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電子物理學系
We construct a reliable actively Q-switched Nd:YVO4 laser to make a comparative study for the second harmonic generation between the extracavity and intracavity configurations under a similar operated condition. The output power at 266 nm as high as 1.67 W is effectually generated with the combination of the extracavity second and fourth harmonic generations under an incident pump power of 26 W at 808 nm and a pulse repetition rate of 40 kHz, corresponding to the conversion efficiency from 808 to 266 nm up to 6.4 %.
Efficient Dual-Wavelength Synchronously Mode-Locked Picosecond Laser Operating on the F-4(3/2) -> I-4(11/2) Transition With Compactly Combined Dual Gain Media
(2015-01-01)
Huang, Yu-Jen
;
Tzeng, Ying-Shuen
;
Tang, Cheng-Yu
;
Chen, Yung-Fu
;
交大名義發表
A novel concept based on the dual gain media is originally proposed for achieving a compact efficient dual-wavelength synchronously mode-locked diode-end-pumped Nd laser on the F-4(3/2) -> I-4(11/2) transition. We theoretically and experimentally realize that the output power ratio between two spectral outputs could be flexibly controlled simply by varying the waist position of the pump beam inside the composite gain medium. With the developed tactic, the total output power at 1.06 m for balancing two-color intensities reaches 2.9 W. Moreover, suppressing the excitation of a few high-order transverse modes enables a fairly stable picosecond pulse train to be achieved with the self mode locking, where the mode-locked pulse width and repetition rate are measured to be 47 ps and 2.86 GHz, respectively. A series of 0.32 THz ultrashort pulses with the effective duration of 1.6 ps is further generated through the optical beating between two carrier frequencies of dual-wavelength synchronous pulses.
Efficient High-Energy Pulsed Pumped Passively Q-switched Nd:YLF/Cr4+:YAG UV Laser At 351 nm with a Nearly Hemispherical Cavity
(2013)
Huang, Yu-Jen
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Tang, Cheng-Yu
;
Su, Kuan-Wei
;
Chen, Yung-Fu
;
電子物理學系
We utilize a nearly hemispherical cavity to develop a pulsed pumped passively Q-switched Nd:YLF/Cr4+:YAG UV laser. The pulse energy and peak power at 351 nm are efficiently generated to be 360 mu J and 44.1 kW.
Electromigration behaviors of Ge2Sb2Te5 chalcogenide thin films under DC bias
(2013-12-15)
Huang, Yin-Hsien
;
Hang, Chi-Hang
;
Huang, Yu-Jen
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
Electromigration (EM) behaviors of pristine Ge2Sb2Te5 (GST), nitrogen-doped GST (N-GST) and cerium-doped GST (Ce-GST) thin-film strips under DC bias are presented. The mean-time-to-failure (MTTF) analysis based on the Black equation found that the EM failure times at room temperature are 1.2 x 10(4), 40 and 9.2 x 10(2) years and the activation energies (E-a) of EM process are 1.07, 0.57 and 0.68 eV for GST, N-GST and Ce-GST, respectively. Moreover, the calibration of the current density exponent, n, of Black's equation found n values are close to 2 for all samples, implying the dominance of grain boundary diffusion during the mass transport of EM process. For doped GSTs, the inferior EM failure lifespans and smaller E-a values were ascribed to the grain refinement effect which increases the number of grain boundaries in such samples. It consequently promoted the short-circuit diffusion and accelerated the EM failure in doped GSTs. The Blech-type tests on GSTs found that the threshold product, i.e., the product of current density and sample length ((j.L)(th)), is 200 A/cm for GST, 50 A/cm for N-GST and 66.67 A/cm for Ce-GST. Moreover, the product of diffusivity and effective charge number (i.e., DZ*) for GST, N-GST and Ce-GST was 2.0 x 10(-7), 4.5 x 10(-6) and 3.8 x 10(-6) cm(2)/sec, respectively. Analytical results illustrated that the electrostatic force effect dominates the EM failure in samples with short strip lengths while the electron-wind force effect dominates the EM failure in samples with long strip lengths. Doping might alleviate the mass segregation in GST; however, its effect was moderate. (C) 2013 Elsevier B.V. All rights reserved.
Extracting photon periodic orbits from spontaneous emission spectra in laterally confined vertically emitted cavities
(2010-08-15)
Chen, Yung-Fu
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Yu, Yan-Ting
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Huang, Yu-Jen
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Chiang, Po-Yi
;
Su, Kuan-Wei
We report our observation of the signature of photon periodic orbits in the spontaneous emission spectra of large-aperture vertical-cavity surface-emitting lasers (VCSELs). The high-resolution measurement clearly demonstrates that over a thousand cavity modes with a narrow linewidth can be perfectly exhibited in the spontaneous emission spectrum just below the lasing threshold. The Fourier-transformed spectrum is analyzed to confirm that the spontaneous emission spectra of large-aperture VCSELs can be exploited to analogously investigate the energy spectra of the 2D quantum billiards. (C) 2010 Optical Society of America
Morphological study on pentacene thin-film transistors: the influence of grain boundary on the electrical properties
(2010-10-13)
Chen, Fang-Chung
;
Chen, Ying-Pin
;
Huang, Yu-Jen
;
Chien, Shang-Chieh
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光電工程學系
We have prepared organic thin-film transistors (OTFTs) featuring pentacene molecules deposited at various substrate temperatures onto either hexamethyldisilazane (HMDS)- or poly(alpha-methylsyrene) (P alpha MS)-treated SiO(2) surfaces. As a result, we obtained different grain boundary densities in the conducting channel. Since the surface-modified devices featured similar grain boundary densities in their active layers, but displayed different electrical performances, we suspected that different trap states probably existed at the grain boundaries for the two different kinds of OTFTs. In addition, the surface morphologies of the initial layers featured grain boundaries that were rather blurred for the thin films prepared on the P alpha MS-treated substrates, whereas shallow boundaries appeared for the pentacene layers on the HMDS-treated surfaces. Therefore, we deduced that the different surface treatment processes resulted in different Schwoebel (step-edge) barriers, and hence, different morphologies. These results suggested that different trap states existed at the grain boundaries of the two types of surface-treated devices, leading to variations in the electrical performance, even though the grain boundary densities were similar.
Morphological study on pentacene thin-film transistors: the influence of grain boundary on the electrical properties
(2010-10-13)
Chen, Fang-Chung
;
Chen, Ying-Pin
;
Huang, Yu-Jen
;
Chien, Shang-Chieh
;
光電工程學系
We have prepared organic thin-film transistors (OTFTs) featuring pentacene molecules deposited at various substrate temperatures onto either hexamethyldisilazane (HMDS)- or poly(alpha-methylsyrene) (P alpha MS)-treated SiO(2) surfaces. As a result, we obtained different grain boundary densities in the conducting channel. Since the surface-modified devices featured similar grain boundary densities in their active layers, but displayed different electrical performances, we suspected that different trap states probably existed at the grain boundaries for the two different kinds of OTFTs. In addition, the surface morphologies of the initial layers featured grain boundaries that were rather blurred for the thin films prepared on the P alpha MS-treated substrates, whereas shallow boundaries appeared for the pentacene layers on the HMDS-treated surfaces. Therefore, we deduced that the different surface treatment processes resulted in different Schwoebel (step-edge) barriers, and hence, different morphologies. These results suggested that different trap states existed at the grain boundaries of the two types of surface-treated devices, leading to variations in the electrical performance, even though the grain boundary densities were similar.
Observation of Repetition Rate Locking in an Orthogonally-Polarized Dual-Wavelength Passively Q-Switched Hybrid Nd:YVO4/Nd:YLF Laser
(2016)
Huang, Yu-Jen
;
Cho, Hsin-Ham
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Chen, Yung-Fu
;
電子物理學系
;
電子工程學系及電子研究所
A dual-wavelength passively-Q-switched laser with orthogonally polarized emission is originally demonstrated by combining the birefringent Nd:YVO4 and Nd:YLF crystals. The phenomenon of repetition rate locking for the two spectral components is experimentally observed and theoretically analyzed.
Organic thin-film transistors with color filtering functional gate insulators
(2008-08-04)
Chuang, Chiao-Shun
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Cheng, Jung-An
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Huang, Yu-Jen
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Chang, Hsiao-Fen
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Chen, Fang-Chung
We developed color filtering functional organic thin-film transistors exhibiting both high field-effect mobilities and color-filtering ability. The conventional colorant inks were utilized as the materials for the color filter/dielectric multifunction layers. In order to improve the electrical performance, a high dielectric polymeric insulator, poly(2,2,2-trifluoroethyl methacrylate), was introduced to modify the surface of the dielectric layer. Further, the Commission Internationale de L'Eclairage chromaticity coordinates were (0.64, 0.34), (0.36, 0.54), and (0.14, 0.15) for red, green, and blue devices, respectively, covering 49.2% National Television Systems Committee standard. This work represents one potential example for multifunctional organic electronics. (C) 2008 American Institute of Physics.
Phase transition behaviors of Mo- and nitrogen-doped Ge(2)Sb(2)Te(5) thin films investigated by in situ electrical measurements
(2009-08-01)
Huang, Yu-Jen
;
Chen, Yen-Chou
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Phase-change behaviors of Ge(2)Sb(2)Te(5) (GST) thin films doped with molybdenum (Mo) or nitrogen (N) were investigated by utilizing in situ electrical property measurement, x-ray diffraction (XRD), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy. It was found that the Mo doping mainly reduces the resistivity level of amorphous GST while the N-doping raises both the resistivity levels of amorphous and crystalline GSTs. XRD and TEM analyses revealed that the element doping stabilizes the amorphous state of GST and suppresses the grain growth in GST films. This resulted in the increase in recrystallization temperature (T(m)) and activation energy (E(a)) of amorphous-to-crystalline phase transition in GST layers, as revealed by the calculation in terms of Kissinger's theory. The results of data fitting into various percolation models and Johnson-Mehl-Avrami analysis indicated the heterogeneous feature of phase transition process in GST layers that the nucleation first occurs at the atmosphere/sample interface and the recrystallization front advances into the interior of sample in a layer-by-layer manner along the direction of surface normal.
Phase transition behaviors of Mo- and nitrogen-doped Ge2Sb2Te5 thin films investigated by in situ electrical measurements
(2009-08-01)
Huang, Yu-Jen
;
Chen, Yen-Chou
;
Hsieh, Tsung-Eong
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Phase-change behaviors of Ge2Sb2Te5 (GST) thin films doped with molybdenum (Mo) or nitrogen (N) were investigated by utilizing in situ electrical property measurement, x-ray diffraction (XRD), transmission electron microscopy (TEM), and x-ray photoelectron spectroscopy. It was found that the Mo doping mainly reduces the resistivity level of amorphous GST while the N-doping raises both the resistivity levels of amorphous and crystalline GSTs. XRD and TEM analyses revealed that the element doping stabilizes the amorphous state of GST and suppresses the grain growth in GST films. This resulted in the increase in recrystallization temperature (T-m) and activation energy (E-a) of amorphous-to-crystalline phase transition in GST layers, as revealed by the calculation in terms of Kissinger's theory. The results of data fitting into various percolation models and Johnson-Mehl-Avrami analysis indicated the heterogeneous feature of phase transition process in GST layers that the nucleation first occurs at the atmosphere/sample interface and the recrystallization front advances into the interior of sample in a layer-by-layer manner along the direction of surface normal.
Phase-Change Kinetics of Bi-Fe-(N) Layer for High-Speed Write-Once Optical Recording
(2011-04-01)
Huang, Sung-Hsiu
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Huang, Yu-Jen
;
Mai, Hung-Chuan
;
Hsieh, Tsung-Eong
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材料科學與工程學系
In this work, we present the phase-change kinetics of Bi-Fe-(N) layers for write-once optical recording. In situ reflectivity measurement indicated that the phase-change temperature (T(x)) of the Bi-Fe-(N) layers is strongly related to the heating rate. The T(x)'s were about 170 degrees C at low heating rates and approached the melting point of the Bi phase (i.e., 271.4 degrees C) at high rate of heating provided by laser heating. For a 100-nm-thick Bi-Fe-(N) layer, Kissinger's analysis showed that the activation energy of phase transition (E(a)) = 1.24 eV, while the analysis of isothermal phase transition in terms of the Johnson-Mehl-Avrami (JMA) theory showed that the average Avrami exponent (m) = 2.2 and the appropriate activation energy (Delta H) = 5.15 eV. With the aid of X-ray diffraction (XRD) analysis, a two-dimensional phase transition behavior in the Bi-Fe-(N) layers initiated by the melting of the Bi-rich phase was confirmed. For optical disk samples with optimized disk structure and write strategy, the signal properties far exceeding the write-once disk test specifications were achieved. Satisfactory signal properties indicated that the Bi-Fe-(N) system is a promising alternative for high-speed write-once recording in the Blu-ray era. (C) 2011 The Japan Society of Applied Physics
Power Scaling in a Diode-End-Pumped Multisegmented Nd:YVO4 Laser With Double-Pass Power Amplification
(2015-01-01)
Huang, Yu-Jen
;
Zhuang, Wei-Zhe
;
Su, Kuan-Wei
;
Chen, Yung-Fu
;
交大名義發表
We demonstrate a high-power master oscillator power amplifier with the double-pass configuration based on the specially designed multisegmented Nd:YVO4 crystals. A powerful mathematical technique on the basis of the Fourier eigenfunction expansion method is developed for precisely calculating the temperature distribution inside the gain medium. A seed Nd:YVO4 oscillator under dual-end pumping is subsequently constructed for efficiently emitting the output power of up to 50 W. Moreover, under a total incident pump power of 244 W at 808 nm, as high as 108 W of the output power at 1064 nm is further generated in our developed master oscillator power amplifier system. Theoretical and experimental results clearly reveal that the gain medium with multiple doping concentrations is practically valuable for constructing a high-power end-pumped laser without bringing in significantly thermal effects.