Browsing by Author "Peng, Tai-Yen"

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Effect of oxygen concentration on characteristics of NiOx-based resistance random access memory
(2007-02-01)
Lee, Ming-Daou
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Ho, Chia-Hua
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Lo, Chi-Kuen
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Peng, Tai-Yen
;
Yao, Yeong-Der
The resistance bistability and the switching effect has been systematically studied in nickel oxide films with variable oxygen concentrations. Both the switching bias voltage and the resistance ratio of RESET to SET were found to be strongly concentration dependent. Meanwhile, the electrical characteristics can be exactly examined by an Schottky emission. By means of mathematical fitting, the resistance bistability seems to be related to the alternating of dielectric constant and the barrier height. Furthermore, the room temperature cycle endurance with a distinguishable operation window was found to exceed 800. This indicates that the nickel oxide has the potential to be a promising material on resistance random access memory.
Effects of an Os buffer layer on structure and exchange bias properties of CoFe/IrMn fabricated on Si(100) and Si(111)
(2007-02-01)
Peng, Tai-Yen
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Lo, C. K.
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Chen, San-Yuan
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Yao, Y. D.
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材料科學與工程學系
The structural and exchange bias properties of CoFe/IrMn prepared on Si (100) and Si (111) with an Os/Cu buffer layer were investigated. Since the Os (0002) surface mesh has the same atomic arrangement as fcc (111) orientation, and the lattice mismatch between Os (0002) and IrMn (111) is as low as 2.6%, the CoFe/IrMn grown on H-Si(100) showed a strong IrMn (111) diffraction peak, while a very weak IrMn (111) peak appeared on H-Si (111). With increasing Os thickness (d(Os)), the IrMn (200) peak was weakened, while the IrMn (111) became strong on H-Si (100). For the CoFe/IrMn grown on H-Si(111), no obvious structural change appeared. Os plays an important role on tuning the IrMn to result in the exchange bias. On the other hand, CoFe/IrMn showed an exchange field (H-ex) on both H-Si(100) and H-Si(111) with the Os buffer layer; however, the magnetization switching process was different due to different the crystalline degree. A sharp magnetization switching process occurs for IrMn(111) on Os/Cu/H-Si(100) with a square hysteresis loop. A 370 and 310 Oe of H-ex was found in textured CoFe/TrMn on Os/Cu/H-Si(100) and Os/Cu/H-Si(111), respectively.
Enhancement of exchange field in CoFe/IrMn by Os/Cu buffer layer
(2007-05-01)
Peng, Tai-Yen
;
Chen, San-Yuan
;
Lo, C. K.
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Yao, Y. D.
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材料科學與工程學系
Enhancement of exchange field (H(ex)) and thermal stability of the textured CoFe/IrMn with Os/Cu buffer layer and Os diffusion barrier layer were studied. As revealed by x-ray Diffraction (XRD), an Os (0002) surface mesh was observed to form on Cu (100)/Si (100). The growth of CoFe (111)/IrMn (111) on such a template is parallel to the Os (0002). With the Os/Cu buffer layer, the CoFe/IrMn presents an enhancement of 70 Oe on H(ex) larger than that without Os/Cu. The H(ex) of the textured sample was 230 Oe at room temperature and it was increased to 330 Oe after 250 degrees C annealing. When the temperature reached 350 degrees C, H(ex) vanished. The increment of the temperature at which the textured and the nontextured sample obtaining their maximum H(ex) and the vanishing temperature of H(ex) were 50 and 75 degrees C, respectively. Furthermore, the CoFe/Os (d)/IrMn slowed down the H(ex) degradation. The sample with d=0.3 nm obtained its maximum H(ex) at 250 degrees C and vanished when it reached 400 degrees C. The combination of CoFe/IrMn with Os/Cu buffer layer and Os barrier layer made the H(ex) higher and also better thermal stability. (c) 2007 American Institute of Physics.
Heteroepitaxial growth of sixfold symmetric osmium on Si (111) and Si (100)
(2007-03-19)
Peng, Tai-Yen
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Lo, C. K.
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Yao, Y. D.
;
Chen, San-Yuan
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材料科學與工程學系
Growing sixfold symmetric osmium (Os) epitaxial films with suitable buffer layers was developed. Using a Cu buffer layer, the lattice mismatch between Os (0002) and Si (100) was significantly reduced from > 30% to similar to 7% to grow Os films with twin relationships and weak sixfold symmetries. On the other hand, the Cu/Au buffer layer was selected to form a fcc (111) surface mesh on H-Si (111)-1x1, and therefore sixfold symmetric Os films were grown due to the lower lattice mismatch. Such growth properties may be applied in the high density magnetic random access memory manufacturing processes to connect the magnetic tunnel junction growth and Cu metal line directly. (c) 2007 American Institute of Physics.
The effect of Os interlayers on the thermal stability of magnetic CoFe/OsMn films
(2006-09-01)
Peng, Tai-Yen
;
Lo, C. K.
;
Chen, San-Yuan
;
Yao, Y. D.
;
材料科學與工程學系
The thermal stability of a multilayer structure of protection layer/Co(90)Fe(10)/Os (d nm)/Os(20)Mn(80) has been studied as functions of annealing temperature (Tan) and thickness of Osmium (Os) layer. The insertion of a thin Os layer between the Co(90)Fe(10)/Os(20)Mn(80) interface shows better thermal stability. No diffusion evidence was found for samples with d >= 0:3 nm as examined by Auger electron spectroscopy depth profile at different annealing temperatures up to 400 degrees C. These samples with Os layer showed the same magnetic behavior and the hysteresis loop with squareness (S) larger than 0.9 were observed before and after annealing. (C) 2006 Elsevier B.V. All rights reserved.