In the advancement of the semiconductor device technology, ZnO could be a prospective alternative... more In the advancement of the semiconductor device technology, ZnO could be a prospective alternative than the other metal oxides for its versatility and huge applications in different aspects. In this review, a thorough overview on ZnO for the application of resistive switching memory (RRAM) devices has been conducted. Various efforts that have been made to investigate and modulate the switching characteristics of ZnO-based switching memory devices are discussed. The use of ZnO layer in different structure, the different types of filament formation, and the different types of switching including complementary switching are reported. By considering the huge interest of transparent devices, this review gives the concrete overview of the present status and prospects of transparent RRAM devices based on ZnO. ZnO-based RRAM can be used for flexible memory devices, which is also covered here. Another challenge in ZnO-based RRAM is that the realization of ultra-thin and low power devices. Nevertheless, ZnO not only offers decent memory properties but also has a unique potential to be used as multifunctional nonvolatile memory devices. The impact of electrode materials, metal doping, stack structures, transparency, and flexibility on resistive switching properties and switching parameters of ZnO-based resistive switching memory devices are briefly compared. This review also covers the different nanostructured-based emerging resistive switching memory devices for low power scalable devices. It may give a valuable insight on developing ZnO-based RRAM and also should encourage researchers to overcome the challenges.
Fabrication of a fiber anode with a mixture of the Gd 2 O 3 and SrO co-doped ceria fibers and
... more Fabrication of a fiber anode with a mixture of the Gd 2 O 3 and SrO co-doped ceria fibers and the Ni nano-catalyzer by using electrospinning and impregnated process were carried out for application in an intermediate temperature fuel cell (ITFC). Experimental results demonstrate that a uniform co-doped ceria fiber of 100 nm diameter could be spun at the concentration of PVP approximately 11.32 wt.% and electric field of 20 kV. The anodic films were prepared via a nickel wet dipping process and sintered at different temperatures. The micrograph of the anode sintered at 1200 o C for1hr has a well defined microstructure in terms of electrolyte area covered with nickel and the triple phase boundary (TPB) between electrolyte, electrode and gas phase. Fiber anode exhibits low polarization resistance and high exchange current density due to formation of the reticular nano-fiber structure. Accordingly, using a new concept of combination of the nano-ceramic fiber and the Ni nano-particle for increasing the catalytic properties of anode is successfully proved, it is found that nano-fiber substituting to powder in anode could decrease the processing temperature of cell and maintain the porous structure of anode to increase the amount of TPB and restrain formation of agglomerates of nickel particles.
The influence of single and double forming on the switching stability of AZO/ZnO 1x /ITO
transpar... more The influence of single and double forming on the switching stability of AZO/ZnO 1x /ITO transparent resistive memory devices was investigated. Devices that underwent single forming exhibited severe switching instability, where as those that underwent double forming exhibited excellent switching uniformity. The quantity of conducting filaments can be limited by applying the two-step forming process. Consequently, the set/reset process can be controlled, enhancing switching stability. Satisfactory endurance with an acceptable ON/OFF ratio of 10 2 and satisfactory retention behavior of 10 4 s at room temperature confirmed the reliability of optimized devices. Furthermore, highly transparent devices (transparency of approximately 85% in visible range) have been fabricated.
The effect of a defect concentration-modified top electrode on the bipolar resistance switching o... more The effect of a defect concentration-modified top electrode on the bipolar resistance switching of trans- parent Al-doped ZnO/ZnO/ITO [AZO(TE)/ZnO/ITO(BE)] devices was investigated. Different oxygen vacancy con- centrations in the top electrode, Al-doped ZnO, can be simply controlled by modulating the sputtering working pressure condition from 1.2 to 12 mTorr. The oxygen vacancy concentration between AZO and ZnO may trigger oxygen diffusion at the interface and affect the switching characteristic. High oxygen release from a ZnO resistive layer caused by excessive oxygen vacancy concentration at the top electrode is responsible for reducing the memory window as a result of reduced oxygen available to rupture the filament. Top electrode based on lower oxygen vacancy concentration has a higher memory window and an asymmetric resistive switching characteristic. However, all set of devices have excellent endurance of more than 104 cycles. This study showed that an Al-doped ZnO top electrode helps not only to achieve a transparent device but also to enhance memory properties by providing a suitable oxygen vacancy concentration.
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Papers by Firman Mangasa
the Ni nano-catalyzer by using electrospinning and impregnated process were carried out for
application in an intermediate temperature fuel cell (ITFC). Experimental results demonstrate that a
uniform co-doped ceria fiber of 100 nm diameter could be spun at the concentration of PVP
approximately 11.32 wt.% and electric field of 20 kV. The anodic films were prepared via a nickel
wet dipping process and sintered at different temperatures. The micrograph of the anode sintered at
1200 o C for1hr has a well defined microstructure in terms of electrolyte area covered with nickel and
the triple phase boundary (TPB) between electrolyte, electrode and gas phase. Fiber anode exhibits
low polarization resistance and high exchange current density due to formation of the reticular
nano-fiber structure. Accordingly, using a new concept of combination of the nano-ceramic fiber and
the Ni nano-particle for increasing the catalytic properties of anode is successfully proved, it is found
that nano-fiber substituting to powder in anode could decrease the processing temperature of cell and
maintain the porous structure of anode to increase the amount of TPB and restrain formation of
agglomerates of nickel particles.
transparent resistive memory devices was investigated. Devices that underwent single forming
exhibited severe switching instability, where as those that underwent double forming exhibited
excellent switching uniformity. The quantity of conducting filaments can be limited by applying
the two-step forming process. Consequently, the set/reset process can be controlled, enhancing
switching stability. Satisfactory endurance with an acceptable ON/OFF ratio of 10
2
and satisfactory
retention behavior of 10
4
s at room temperature confirmed the reliability of optimized devices.
Furthermore, highly transparent devices (transparency of approximately 85% in visible range) have
been fabricated.