Browsing by Author "Lee, H. Y."

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Highly Scalable Hafnium Oxide Memory with Improvements of Resistive Distribution and Read Disturb Immunity
(2009)
Chen, Y. S.
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Lee, H. Y.
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Chen, P. S.
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Gu, P. Y.
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Chen, C. W.
A 30x30 nm(2) HfOx resistance random access memory (RRAM) with excellent electrical performances is demonstrated for the scaling feasibility in this work. A 1 Kb one transistor and one resistor (1T1R) array with robust characteristics was also fabricated successfully. The device yield of the 1 Kb array is 100%, and the endurance for these devices can exceed 10(6) cycles by a pulse width of 40 ns. Two effective verification methods, which make a tight distribution of high resistance (R-HIGH) and low resistance (R-LOW) are proposed for the array to ensure a good operation window. A thin A1O(x) buffer layer under the HfOx layer was adopted to enhance the read disturb immunity. Without large parasitic capacitance, the 1T1R RRAM devices exhibit excellent program(PGM)/erase(ERS) disturb immunity.
Multilayered optical bit storage in Sm(DBM)(3)Phen-doped poly(methyl methacrylate) read out by fluorescence and reflection modes
(2010-12-08)
Nie, Z. G.
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Lim, K. S.
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Jang, W. Y.
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Lee, H. Y.
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Lee, M. K.
We report on multilayer optical data storage using Sm(DBM)(3)Phen-doped poly(methyl methacrylate) and a tightly focused 800 nm, 1 kHz, 100 fs pulsed laser. After pulsed femtosecond laser irradiation, refractive-index change and a visible fluorescent bit were formed at the irradiated position inside the bulk sample. The photoluminescence should result from the ligands peeled from the central Sm(3+) ions via bond scission induced by laser irradiation. Multilayer patterns recorded by tightly focusing the pulsed laser beam were read out by a reflection-type fluorescence confocal microscope, which can detect the scattered signal and also the fluorescent signal of the stored bits. The dependence of fluorescence and scattering signals on recording pulse energy was examined. The signal-to-noise ratios via two retrieval modes were compared as a function of recording depth. The detection of the fluorescence signal enables retrieval of the stored bits with a higher S/N ratio.
Multilayered optical storage in Sm(DBM)(3)Phen-doped and un-doped polymethylmethacrylate by a femtosecond laser
(2011)
Nie, Z. G.
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Jang, W. Y.
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Lim, K. S.
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Lee, M. K.
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Lee, H. Y.
We report on multilayered optical storage in Sm(DBM)(3)Phen-doped and un-doped polymethylmethacrylate read out by fluorescence and reflection modes. The detection of fluorescence signal enables retrieval of the stored bits with a higher signal-to-noise ratio. (C) 2011 Optical Society of America
New Observations on the Regular and Irregular Noise Behavior in a Resistance Random Access Memory
(2014-01-01)
Chen, Scott C. H.
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Huang, Y. J.
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Chung, S. S.
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Lee, H. Y.
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Chen, Y. S.
In this paper, a new type of noise, different from the conventional Random Telegraph Noise (RTN), has been found and analyzed in a resistance random access memory (RRAM). The regular RTN signal is governed by the trapping and detrapping of the electrons. It will appear regularly with a two-level current and the amplitude of the RTN is smaller. However, an abnormal noise, called giant noise, was observed from the oxygen migration. The amplitude of the giant noise is much larger than the RTN one. Also, two different types of giant noise were observed depending on the movement of the oxygen vacancies. All of the above various types of noise might play an important role in the readout error in an RRAM. Therefore, these noise effects need further attention in the design of RRAM.
Structure of HfO2 films epitaxially grown on GaAs(001)
(2006-09-18)
Hsu, C. -H.
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Chang, P.
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Lee, W. C.
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Yang, Z. K.
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Lee, Y. J.
High-quality HfO2 films of technologically important thickness ranging from 1.8 to 17 nm have been grown epitaxially on GaAs (001) by molecular beam epitaxy. Thorough structural and morphological investigations were carried out by x-ray scattering and high-resolution transmission electron microscopy. The films exhibit an atomically sharp interface with the substrate and are of a monoclinic phase with predominant (001)-plane epitaxy between the HfO2 films and GaAs, in spite of a large lattice mismatch of > 8.5%.
The Physical Insights Into an Abnormal Erratic Behavior in the Resistance Random Access Memory
(2013)
Huang, Y. J.
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Chung, Steve S.
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Lee, H. Y.
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Chen, Y. S.
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Chen, F. T.
The voltage ramping rate during the forming and set-reset process is strongly related to the formation of soft-breakdown (SBD) paths. In this paper, we examined the effect of two different operation methods in RRAM, including sweep and pulse modes. The RTN analysis has been utilized to examine their influences on the SBD paths. For the first time, we found a different behavior of the RTN currents generated by two different modes of operation. Results show that more SBD paths are created during the pulse mode which led to the instability of switched resistance, and induced the erratic bit during the readout of RRAM.