Browsing by Author "Perng, Tsong-Pyng"

Now showing 1 - 5 of 5

Effects of interfacial sulfidization and thermal annealing on the electrical properties of an atomic-layer-deposited Al(2)O(3) gate dielectric on GaAs substrate
(2008-04-01)
Cheng, Chao-Ching
;
Chien, Chao-Hsin
;
Luo, Guang-Li
;
Yang, Chun-Hui
;
Chang, Ching-Chih
In this study we investigated the interfacial chemistry occurring between an atomic-layer-deposited Al(2)O(3) high-k film and a GaAs substrate and the impact of sulfidization and thermal annealing on the properties of the resultant capacitor. We observed that sulfide passivation of the Al(2)O(3)/GaAs structure improved the effect of Fermi level pinning on the electrical characteristics, thereby providing a higher oxide capacitance, smaller frequency dispersion, and reduced surface states, as well as decreased interfacial charge trapping and gate leakage currents. Photoemission analysis indicated that the (NH(4))(2)S-treated GaAs improved the quality of the as-deposited Al(2)O(3) thin film and preserved the stoichiometry of the dielectric during subsequent high-temperature annealing. This behavior was closely correlated to the diminution of GaAs native oxides and elemental arsenic defects and their unwanted diffusion. In addition, thermal processing under an O(2) atmosphere, relative to that under N(2), decreased the thickness of the Al(2)O(3) gate dielectric and relieved the gate leakage degradation induced by metallic arsenic; as a result, superior dielectric reliability was attained. We discuss the underlying thermochemical reactions that account for these experimental observations. (C) 2008 American Institute of Physics.
Efficient inverted organic solar cells without an electron selective layer
(2011)
Wang, Jen-Chun
;
Lu, Cheng-Yueh
;
Hsu, Jui-Lin
;
Lee, Ming-Kun
;
Hong, Yun-Ru
Inverted organic solar cells which required no electron selective layer were fabricated and their power conversion efficiency was found to improve irreversibly from 1.46% to 4.10% with post-processing light soaking for 2 hours. X-Ray photoelectron spectroscopy characterization revealed further segregation in surface composition at the interface and was found to explain the current density-voltage measurements. In addition, the light soaked devices were found to exhibit extended lifetime as compared to conventional devices. Since no electron selective layer was required, light soaking may be considered as a cost-effective method to achieve efficient inverted organic solar cells.
Electrical and material characterization of atomic-layer-deposited Al(2)O(3) gate dielectric on ammonium sulfide treated GaAs substrates
(2008)
Cheng, Chao-Ching
;
Chien, Chao-Hsin
;
Luo, Guang-Li
;
Chang, Ching-Chih
;
Kei, Chi-Chung
This paper has studied the electrical and interfacial properties of atomic-layerdeposited Al(2)O(3) thin film on ammonium-sulfide passivated GaAs. It was found that the Al(2)O(3) deposited at 300 degrees C relative to that at 100 degrees C showed the nearly four orders of magnitude reduction in gate leakage current at the capacitance-equivalent-thickness of 40 angstrom. The capacitance-voltage (C-V) characteristics displayed the higher oxide capacitance, reduced frequency dispersion and less charge trapping when GaAs receiving (NH(4))(2)S sulfide immersion; these improvements can be reasonably explained by the suppression of both native oxides and the resultant improved interface quality. Annealing as-deposited Al(2)O(3)/GaAs structures at high temperatures further reduces the Fermi level pinning effect on accumulation capacitance, however, causes an increase in C-V frequency dispersion and gate leakage current. We suggested that these phenomena are strongly associated to the amount of As-related defects resided at the dielectric/ substrate interface during thermal desorption.
Facile fabrication of titania-ordered cubic mesoporous carbon composite: Effect of Ni doping on photocatalytic hydrogen generation
(2019-07-19)
Rath, Purna Chandra
;
Mishra, Mrinalini
;
Saikia, Diganta
;
Chang, Jeng Kuei
;
Perng, Tsong-Pyng
Hitherto TiO2 is the most popular catalyst for photocatalytic H-2 generation and reduction of organic pollutants due to its chemical inertness, high activity, and abundance. In this work, ordered mesoporous carbon CMK-8 supported TiO2 nanoparticles loaded with non-noble metal Ni, denoted as Ni-TiO2@CMK-8 are fabricated for application in photocatalytic H-2 generation. Our results demonstrate that the developed composite exhibit exceptional photocatalytic activity for H-2 generation (3556 mu mol g(-1)) under 300 W Xe lamp irradiation (with an external quantum efficiency of 37.9%), which is around 10 times higher than pure TiO2 and 4 times that of TiO2@CMK-8. The enhanced photocatalytic performance is attributed to the well-dispersed TiO2 in the ordered mesoporous carbon structure of CMK-8. The performance is boosted by the black body-like light absorbance of CMK-8 and plasmonic effect of Ni. Enhanced UV-visible light absorbance, large surface area and the loaded Ni metal synergistically improve the charge-carrier kinetics to attain highly efficient photocatalytic H-2 generation. The Ni-TiO2@CMK-8 composite shows enhanced activity for the reduction of 4-nitrophenol as well. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Highly efficient flexible inverted organic solar cells using atomic layer deposited ZnO as electron selective layer
(2010-02-07)
Wang, Jen-Chun
;
Weng, Wei-Tse
;
Tsai, Meng-Yen
;
Lee, Ming-Kun
;
Horng, Sheng-Fu