Browsing by Author "Chang, Kai-Hsiang"

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Characterization of AC Hot-Carrier Effects in Poly-Si Thin-Film Transistors
(2009-11-01)
Lin, Horng-Chih
;
Chang, Kai-Hsiang
;
Huang, Tiao-Yuan
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper, we employed a new test structure to characterize the alternating-current (ac) hot-carrier (HC)induced degradation in poly-Si thin-film transistors. High sensitivity in detecting the damage and the capability of directly resolving the damage location are demonstrated due to the unique feature of the test structure. Our results indicate that the major degradation is induced in the turn-off stages of the ac-stress signal when applied to the gate and in the turn-on stages of the ac-stress signal when applied to the drain. The availability and energy relaxation of channel HCs are considered to explain the experimental findings.
Effective density-of-states distribution of polycrystalline silicon thin-film transistors under hot-carrier degradation
(2007-09-01)
Lee, Ming-Hsien
;
Chang, Kai-Hsiang
;
Lin, Horng-Chih
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this work, quantitative information for nonuniform hot-carrier degradation, especially under mild stressing condition, is investigated. A test structure capable of revealing hot-carrier degradations of polycrystalline silicon (poly-Si) thin-film transistors in specific portions of the channel is employed. Effective density-of-states (DOS) distributions at the damaged sites can be extracted using field-effect conductance method, thus providing an effective tool to evaluate the impact of hot-carrier degradations. By measuring along individual sections of the channel, it becomes possible to extract the DOS for the device as a whole. The combination of the proposed test structure and DOS extraction technique also provides a powerful tool for modeling and simulating current-voltage characteristics of thin-film transistors under hot-carrier stressing. (c) 2007 American Institute of Physics.
Spatially and temporally resolving the degradation of n-channel poly-Si thin-film transistors under hot-carrier stressing
(2007-03-01)
Lee, Ming-Hsien
;
Chang, Kai-Hsiang
;
Lin, Horng-Chih
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A test structure was proposed to investigate the spatial and temporal evolution of hot-carrier degradation in n-channel poly-Si thin-film transistors. Our experimental results clearly show that the initial damage during the early stage of hot-carrier stressing, which is still undetectable by conventional test structures, can be easily observed by the structure. In addition, the proposed test structure is also capable of resolving the evolution of the degradation along the channel, thus providing a powerful tool to study the location-dependent damage mechanisms. (c) 2007 American Institute of Physics.
Spatially resolving the degradation of SPC thin-film transistors under AC stress
(2007)
Chang, Kai-Hsiang
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Lee, Ming-Hsien
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Lin, Horng-Chih
;
Huang, Tiao-Yuan
;
Lee, Yao-Jen
Suppression of "volcano" morphology and parasitic defect luminescence in AlGaN-based deep-UV light-emitting diode epitaxy
(2019-06-01)
Huang, Chia-Yen
;
Liu, Tsung-Yen
;
Huang, Shih-Ming
;
Chang, Kai-Hsiang
;
Tai, Tsu-Ying
In this study we overcame several critical growth issues related to epitaxy in AlGaN deep-ultraviolet lightemitting diodes. Irregular-shaped pits with dislocation clusters were observed in micron-thick layers of AlGaN on AlN. The strain-induced morphology and defects were suppressed after the insertion of superlattice transition layers between the AlGaN and AlN layers. The defect luminescence in the active region was governed by radiative recombination through the oxygen shallow donors and deep acceptors related to III-vacancies. After optimization of the growth conditions and a decrease in growth interruption, the intensity of the parasitic blueband emission was suppressed by up to 95%. Energy dispersive spectroscopy suggests that the desorption of gallium from the surface is the major source of the III-vacancies.