Browsing by Author "Liu, K. C."

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Bipolar resistive switching characteristics of Gd2O3 thin film structure
(2011)
Chang, K. M.
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Tzeng, W. H.
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Liu, K. C.
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Chan, Y. C.
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Kuo, C. C.
The resistive switching (RS) behavior of the Ti/Gd2O3/Pt capacitor structure is fabricated and discussed in this paper. The switching characteristics operated under positive bias exhibits stable switching properties with a condensed voltage and resistance values dispersion, while the switching characteristics becomes unstable and large fluctuation on switching parameters under the negative bias operation. We suggest that the anode electrode plays an important role to the switching characteristics, and might be the causes of the asymmetry of the I-V curves between positive and negative operation. Constant voltage stress measurement is also tested to reveal the switching mechanism of the Gd2O3 film, and the switching mechanism is mainly based on the applied voltage and thermal Joule heat.
Improving the Channel Utilization of IEEE 802.11p/1609 Networks
(2009)
Wang, S. Y.
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Chou, C. L.
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Liu, K. C.
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Ho, T. W.
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Hung, W. J.
The IEEE 802.11p/1609 standards specify a suite of communication protocols for vehicular communication networks. A new operational mode, called the WAVE (Wireless Access in Vehicular Environments) mode, is defined to enable communication among high-speed vehicles or between a vehicle and a roadside infrastructure network. In the WAVE mode, a mobile/stationary station uses a combined FDMA/TDMA channel access scheme to switch its channel between the control channel and a service channel every 50 ms. The primary purpose of this design is to detect new services announced by other stations. However, if a station would like to use all of its service channel bandwidth to transmit a large volume of data to another station, switching back to the control channel every 50 ms without doing anything useful only unnecessarily reduces the maximum possible transmission throughput by a half. To overcome this problem, in this paper we propose an improved channel access scheme to allow a station to stay on a service channel as long as it requires before returning to the control channel. Our simulation results show that the proposed scheme significantly improves the service channel utilization under various network conditions.
Modulation of the Electrical Characteristics of HfOx/TiN RRAM Devices through the Top Electrode Metal
(2010)
Chang, K. M.
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Tzeng, W. H.
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Liu, K. C.
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Lai, W. R.
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電子工程學系及電子研究所
The effect of the top electrode on switching characteristics of a HfOx/TiN structure was investigated. From the electrical conduction analysis, the conduction mechanism between Pt and Ti was found to be quite different. A potential barrier formed in the Pt/HfOx interface showing the Fowler-Nordheim tunneling at high bias. However, it was not observed in the Ti/HfOx structure. Reactive metal Ti interacted with the underlying HfOx film leading to destruction of the barrier height. As such, the device lost the ability to operate at the mu A compliance current range. Pt/HfOx demonstrated the merit of a large resistance ratio and a low operation current (Ireset = 20 mu A). However, Ti/HfOx exhibited better voltage dispersion at the low resistance state (0.5V dispersion). The electrode plays a dominant role in determining the electrical characteristics of a resistive random access memory (RRAM) device. Therefore, choosing an adequate electrode for RRAM is an important consideration.
Stability of High Performance p-type SnO TFTs
(2015)
Zhong, C. W.
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Tsai, H. Y.
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Lin, H. C.
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Liu, K. C.
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Huang, T. Y.
High performance p-type SnO TFTs were fabricated and characterized in this work. Owing to thermal oxygen annealing process, the originally tin-rich oxide film was transformed into a polycrystalline SnO, resulting in decent field-effect mobility and high on/off current ratio. Electrical stability was evaluated by examining the threshold voltage shift under negative bias stresses at different stress times. A scenario considering the passivation/de-passivation of acceptor defects in the channel and the hole trapping of the gate oxide is proposed to explain the observed instability of the SnO TFTs.