Aloe vera gel as an environmentally safe and natural material as an organic dielectric layer used in electronic application has been systematically investigated in this work. The commercially ...purchased gel was deposited on glass substrate by screen printing technique. Effect of drying temperature and duration on the quality of the Aloe vera layer had been examined. The lowest leakage current density was obtained in sample dried at 40 °C for 30 min but electrical breakdown voltage of the sample had reduced as the drying duration was extended more than 40 min. In addition, effect of successive applying the Aloe vera layer and distance between two electrodes on the leakage current of the dielectric had been reported. It was found that single layered Aloe vera had the lowest leakage current density but there was no significant effect of the distance between two electrodes on the leakage current of the dielectric. The produced natural Aloe vera gel after being dried was having a dielectric constant of 3.39 and therefore it had been demonstrated that this material is a potential candidate to be used as a dielectric material in an organic-based electronic device.
Laser dicing of ultrathin dies is promising and is gaining importance because of its cost and quality advantages over mechanical and plasma dicing. However, the effects of laser dicing on the ...mechanical strength and microstructure of ultrathin Si dies need to be further understood, especially when dicing through Si wafers with backside Cu layer. A critical phenomenon effecting the Si die sidewall strength after nanosecond laser dicing of Si wafers with backside Cu is the formation and separation of a SiO
2
layer at the sidewall. The mechanisms behind the SiO
2
layer formation and separation were studied in this work. Si wafer samples without and with backside Cu layer were prepared by dicing with nanosecond laser using standard production parameters. The microstructure and phases formed were investigated by energy dispersive spectroscopy and nanobeam diffraction in a transmission electron microscope. In die samples without backside Cu, the sidewall consists of a thin surface layer of amorphous Si, followed by a polycrystalline Si layer, and finally an epitaxial Si layer. In die samples with backside Cu, the sidewall microstructure was observed to be vastly different. At the upper region of the sidewall, a surface layer of polycrystalline Cu was found, followed by a polycrystalline Cu
3
Si layer, a SiO
2
layer mixed with Cu
3
Si, and finally a thick SiO
2
layer. The Cu
3
Si catalyzes the growth of the SiO
2
through an oxidation step of the Cu
3
Si on the sidewall surface as well as at the SiO
2
/Si interface. In the lower region of the sidewall, the microstructure is similar to the upper region, but there is a separation of the SiO
2
layer from the crystalline Si. The SiO
2
undergoes a decomposition reaction at the SiO
2
/Si interface, releasing volatile SiO which causes microvoids to form and grow laterally at the interface. The growth and coalescence of the microvoids eventually lead to the separation of the SiO
2
layer from the crystalline Si, leaving behind a clean and rough crystalline Si surface with a peak-to-peak roughness of 100–200 nm. In the areas where the SiO
2
layer has separated from the Si die sidewall, the fracture strength of the sidewall is dependent on the material property and surface roughness of the crystalline Si, and not on the SiO
2
layer. In the sidewall region near the die frontside, the SiO
2
thickness is more than regions near the die backside, and no microvoiding and separation at the SiO
2
/Si interface were detected. This is hypothesized to be due to a higher O
2
pressure at the upper region of the narrow dicing trench which is open to the atmosphere compared to the lower regions where there could be O
2
deprivation and lower O
2
pressure.
•Gold nanoparticles (NPs) were spin-coated on linker-free Si substrates.•Density of NPs on n-Si was significantly higher than that of p-Si substrate.•Protonation of –OH created a net positive charge ...on Si thus, immobilized NPs.•Density of NPs on Si substrate was manipulated by the number of depositions.•Embedded NPs in Al Schottky contact raised current density of diodes.
Given the enormous importance of Au nanoparticles (NPs) deposition on Si substrates as the precursor for various applications, we present an alternative approach to deposit Au NPs on linker-free n- and p-type Si substrates. It is demonstrated that, all conditions being similar, there is a significant difference between densities of the deposited NPs on both substrates. The Zeta-potential and polarity of charges surrounding the hydroxylamine reduced seeded growth Au NPs, are determined by a Zetasizer. To investigate the surface properties of Si substrates, contact angle measurement is performed. Field-emission scanning electron microscope is then utilized to distinguish the NPs density on the substrates. Finally, Al/Si Schottky barrier diodes with embedded Au NPs are fabricated, and their structural and electrical characteristics are further evaluated using an energy-filtered transmission electron microscope and current–voltage measurements, respectively. The results reveal that the density of NPs is significantly higher on n-type Si substrate and consequently has more pronounced effects on the electrical characteristics of the diode. It is concluded that protonation of Si–OH group on Si surface in low pH is responsible for the immobilization of Au NPs, which eventually contributes to the lowering of barrier height and enhances the electrical characteristics.
Aloe vera gel was extracted, formulated and deposited as thin films by a facile solution process for memory application. The memory cell features a simple structure, in which a dried Aloe vera film ...was sandwiched in between an Ag top and ITO bottom electrode that was deposited on a glass substrate. Digital information can be encoded and stored as different resistance states of the Aloe vera film. Experimental results reveal that bipolar resistive switching behavior of the Aloe vera film is due to electrochemical growth and dissolution of metallic filaments connecting the top and bottom electrodes. The resistive switching behavior is highly reproducible with an ON/OFF ratio of over 104, a retention time of over 12h, and can endure more than 100 switching cycles. Therefore, the Aloe vera film can serve as a promising platform for sustainable development of green electronics.
Ultrathin silicon die is a key enabler for high performance semiconductor devices and ultrathin packaging. The quality of ultrathin wafers and dies has a significant influence on packaging assembly ...yield and device reliability. The key quality characteristics of ultrathin wafers and dies are bow/warpage, total thickness variation (TTV), subsurface damage (SSD), surface roughness, and mechanical strength. Wafer and die bow/warpage cause handling and processing problems in manufacturing processes, and induce defects during various packaging assembly processes that eventually lead to device reliability issues. The wafer TTV requirement is becoming more stringent for new generations of thin and 3-D packages. SSD, surface roughness, and dicing defects have adverse effects on die mechanical strength and reliability. Therefore, characterization methods are needed for these quality characteristics to control the manufacturing processes for ultrathin wafers and dies to ensure good device performance and reliability. The following ultrathin wafer and die characterization techniques are discussed in this paper: noncontact bow/warp/TTV measurement, materialographic analysis with optical and electron microscopy, high-resolution X-ray diffraction, micro-Raman spectroscopy, scanning infrared depolarization, optical profilometry, atomic force microscopy, and uniaxial/biaxial bending tests.
Photocatalytic degradation by the titanium dioxide (TiO2) photocatalyst attracts tremendous interest due to its promising strategy to eliminate pollutants from wastewater. The floating photocatalysts ...are explored as potential candidates for practical wastewater treatment applications that could overcome the drawbacks posed by the suspended TiO2 photocatalysis system. The problem occurs when the powdered TiO2 applied directly into the treated solution will form a slurry, making its reuse become a difficult step after treatment. In this study, the immobilization of titanium dioxide nanoparticles (TiO2 NPs) on the floating substrate (cork) employing polyvinyl alcohol (PVA) as a binder to anchor TiO2 NPs on the surface of the cork was carried out. Characterizations such as Fourier transformer infrared, X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–vis), zeta potential, photoluminescence spectroscopy, femtosecond to millisecond time-resolved visible to mid-IR absorption spectroscopy, ion chromatography, and scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM–EDX) analyses were employed. XRD analysis revealed the formation of anatase-phase TiO2 NPs. The results demonstrated that the crystallite size was 9.36 nm. The band gap energy of TiO2 NPs was determined as 3.0 eV. PL analysis verified that TiO2 NPs possessed a slower recombination rate of electron–hole pairs as compared to anatase TiO2. The result was attributed by the behavior of photogenerated charge carriers on TiO2 NPs, which existed as shallowly trapped electrons that could survive longer than a few milliseconds in this study. Furthermore, SEM–EDX analysis indicated that TiO2 NPs were well distributed on the surface of the cork. At the optimal mole ratio of TiO2/PVA (1:8), the TiO2/PVA/cork floating photocatalyst degraded at 98.43% of methylene blue (MB) under a visible light source which performed better than under sunlight irradiation (77.09% of MB removal) for 120 min. Besides, the mineralization result has measured the presence of sulfate anions after photocatalytic activities, which achieved 86.13% (under a visible light source) and 65.34% (under sunlight). The superior photodegradation performance for MB was mainly controlled by the reactive oxygen species of the superoxide radical (•O2 –). The degradation kinetics of MB followed the first-order kinetics. Meanwhile, the Langmuir isotherm model was fitted for the adsorption isotherm. The floating photocatalyst presented good reusability, resulting in 78.13% of MB removal efficiency even after five cycles. Our TiO2/PVA/cork floating photocatalyst fabrication and high photocatalytic performance are potentially used in wastewater treatment, especially under visible light irradiation.
Resistive switching properties of nanoscale zirconium dioxide (ZrO
2
) thin film deposited by plasma-enhanced atomic layer deposition (PE-ALD) have been investigated. A resistive memory device has ...been formed with a 10-nm-thick ZrO
2
film as an active switching layer sandwiched between an aluminum top electrode and a silver bottom electrode. Bipolar resistive switching characteristics were demonstrated by current–voltage measurements with a read memory window of 6.6 V, an ON/OFF current ratio of nearly 10
5
, and a retention time of 10
4
s. Current conduction at low resistance states follows Ohm’s law while at a high-resistance state governed by space charge limited conduction. These indicate that the switching mechanism is attributed to filamentary conduction. A SPICE model was applied to model the device, with simulation measurement data in good agreement. This study proves the potential applications of PE-ALD ZrO
2
for non-volatile resistive random access memories.
ZrO2 thin films on Si substrate Wong, Yew Hoong; Cheong, Kuan Yew
Journal of materials science. Materials in electronics,
10/2010, Letnik:
21, Številka:
10
Journal Article
Recenzirano
In the advancement of metal–oxide–semiconductor technology, Si-based semiconductor, with SiO
2
as outstanding dielectric, has been dominating microelectronic industry for decades. However, the ...drastic down-scaling in ultra-large-scale integrated circuitry has made ultrathin SiO
2
(~1.2 nm) unacceptable for many practical reasons. Introduction of ZrO
2
as high-
κ
dielectrics replacing SiO
2
is undeniably a potential yet formidable solution for the aforementioned problem. The objective of this review is to present the current knowledge of ZrO
2
thin film as gate dielectric on Si, in terms of its material and electrical properties produced by various deposition techniques. One of the techniques being focused is thermal oxidation of sputtered Zr and the mechanisms of transforming the metal into oxide has been extensively reviewed.
Current conduction mechanisms through as-deposited and post-deposition annealed (200–800 °C) RF-magnetron sputtered Y2O3 gate oxides on n-type GaN have been systematically investigated with ...current–voltage measurements at temperature in the range of 25–175 °C. The possible current conduction mechanisms that govern the leakage current of Y2O3/GaN metal-oxide-semiconductor test structure are space-charge-limited conduction, Schottky emission, Poole–Frenkel emission, and Fowler-Nordheim tunneling. The dominance of these conduction mechanisms is depending on applied electric field and measurement temperatures.
•Current conduction mechanisms are investigated for Y2O3/GaN structure.•Change of conduction mechanisms is dependent on annealing temperature.•The dominance of conduction mechanisms are influenced by electric field.•Measurement temperature is affecting the governing conduction mechanisms.
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