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Transparent conductive oxide (TCO) film is the most widely used front electrode in silicon heterojunction (SHJ) solar cells. A copper metallization scheme can be applied to the SHJ process. The abundance of zinc in the earth’s crust makes aluminum-doped zinc oxide (AZO) an attractive low-cost substitute for indium-based TCOs. No work has focused on the properties of the copper and AZO layers on the textured silicon for solar cells. This work deposited an aluminum-doped zinc oxide layer and copper metal layer on textured (001) silicon by a sputtering to form Cu/AZO/Si stacks. The structures of Cu/AZO/Si are characterized by scanning electron microscope (SEM), scanning transmission electron microscope (STEM), and energy-dispersive X-ray spectrometer (EDS). The results show that the copper thin film detached from AZO in the valley of the textured silicon substrate at a temperature of 400 °C. Additionally, the gap between the copper and AZO layers increases as temperature increases, and the 65 nm thickness AZO layer was found to be preserved up to 800 °C.

This study investigated the structure and magnetic properties of Co40Fe40V20 thin films with a thicknesses (tf) of 10 nm to 100 nm on a glass substrate. The X-ray diffraction (XRD) patterns of the CoFeV films demonstrated a significant crystalline body-centered cubic (BCC) CoFe (110) structure when the thickness was between 60 and 100 nm, and an amorphous status were shown when the thickness was from 10 to 50 nm. The strongest crystalline XRD peak was at 60 nm because it had a continuous mode of film growth and induced a large grain distribution. The low-frequency alternating current magnetic susceptibility (ϰac) property decreased when the frequency increased. The lowest ϰac value was detected at 60 nm owing to the large grain distribution inducing high coercivity (Hc) and then enhancing the spin coupling strength. The external field (Hext) was difficult to rotate spin state, then deduces the spin sensitivity and ϰac value is decreased. The highest ϰac meant the spin sensitivity was maximized at the optimal resonance frequency. The 50-mm thickness had the highest ϰac 0.045 value at an fres of 100 Hz. The fres value was less than 1000 Hz at all CoFeV thicknesses, suggesting that CoFeV films would be suitable for low-frequency magnetic component applications. Moreover, the saturation magnetization (Ms) revealed a thickness effect when the thicknesses had a larger Ms. The Hc values were between 3 Oe and 10 Oe at all CoFeV films, except for 60 nm. The Hc of the 60 nm film was about 80 Oe due to the larger grain distribution, and it induced strong remanent magnetization (Mr) and a larger squareness ratio (Mr/Ms) of 92%. The results of the magnetic measurement showed that the 60 nm Co40Fe40V20 film had greater Hc and a good squareness ratio.

The low-frequency alternating current magnetic susceptibility (χac) property decreased when the frequency increased. The highest χac meant the spin sensitivity was maximized at an fres. Of ...

The following structures are deposited under the conditions (a) glass/Ru(X nm)/Co60Fe20V20(5 nm) and (b) glass/Ta(Y nm)/Co60Fe20V20(5 nm) at room temperature (RT), where X and Y is from 5 nm to 10 nm. X-ray diffraction (XRD) patterns of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) reveal a weak crystallization at peak β-(200) as the thicknesses of Ta increase from 8 nm to 10 nm, and the patterns indicate an amorphous state as the thicknesses of all Ru films and Ta thicknesses increase from 5 nm to 7 nm. The average contact angles of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) are less than 90° with testing liquids deionized (DI) water and glycerol. The average contact angle of water on the surface is nearly 90 degrees, indicating it is hydrophobic. Moreover, the maximum surface energy of glass/Ru(9 nm)/Co60Fe20V20(5 nm) and glass/Ta(10 nm)/Co60Fe20V20(5 nm) are 44.5 mJ/m2 and 37.4 mJ/m2, demonstrating that the high surface energy corresponds to a strong adhesion, which can be combined with a magnetic tunneling layer of MgO or AlOx and is compatible with other semiconductor processes in magnetic recording media and photoelectric applications.

When B and V are added to CoFe material, the mechanical strength and spin tunneling polarization of a CoFe alloy can be improved and enhanced by the high tunneling magnetoresistance (TMR) ratio. Based on these reasons, it is worthwhile investigating Co40Fe40V10B10 films. In this work, X-ray diffraction (XRD) showed that Co40Fe40V10B10 thin films have some distinct phases including CoFe (110), CoFe (200), FeB (130), and V (110) diffracted peaks with the strongest diffracted peak for 30 nm. The lowest low-frequency alternate-current magnetic susceptibility (&chi, ac) was detected at 30 nm because the large grain distribution inducing that high coercivity (Hc) enhances the spin coupling strength and low &chi, ac. The external field (Hext) had difficulty rotating in the spin state, hence, the spin sensitivity was reduced and the &chi, ac value decreased due to increased surface roughness. The 20 mm thickness had the highest &chi, ac 1.96 &times, 10&minus, 2 value at 50 Hz of an optimal resonance frequency (fres). The surface energy increased from 34.2 mJ/mm2 to 51.5 mJ/mm2 for Co40Fe40V10B10 films. High surface energy had corresponding strong adhesive performance. According to the magnetic and surface energy results, the optimal thickness is 20 nm due as it had the highest &chi, ac and strong adhesion.

This study investigated the structure and magnetic properties of Co

Copper nanowire networks (NWs) coated with a graphene layer through a carbon-enclosed chemical vapor deposition technique at a low temperature of 400 °C with a low sheet resistance of 23.2 Ω sq−1 and a high transmittance of 83.4%, which is comparable to the typical values of tin-doped indium oxide (ITO), as a transparent conducting electrode were demonstrated. The graphene-coated copper NW networks retain a low sheet resistance of less than 25 Ω sq−1 even after annealing at a temperature of 240 °C in a pure oxygen environment for 1 h, while a sheet resistance less than 100 Ω sq−1 can still be maintained in natural sea water, and acidic and basic solutions. Their highly stable features in harsh environments make these graphene-coated copper nanowire networks suitable as a catalyst toward high-efficiency hydrogen evolution reactions (HERs) with a low overpotential of 252 mV at 10 mA Cm−2 and a low Tafel slope of 67 mV dec−1. The non-corrosive and anti-oxidant graphene-coated copper nanowire networks could be used as an alternative transparent conducting electrode in harsh environments, such as in tandem photocatalytic water splitting.

Thin, stacked films of Cu (1 μm)/RuxCo1-x(100 nm) were deposited on textured NiSiy/Si by electroplating. The Cu/RuxCo1-x/NiSiy/Si structure was then annealed at temperatures of 300–800 °C to evaluate the thermal stability. The structures of Cu/RuxCo1-x/NiSiy/Si characterized by scanning electron microscopy (SEM), scanning transmission electron microscope (STEM), energy dispersive X-ray spectrometer (EDS), and powder X-ray diffraction (XRD). The results demonstrated that the Cu/RuxCo1-x/NiSiy/Si stack could be maintained up to 400 °C. For the Cu/RuxCo1-x/NiSiy/Si stack with x = 0.9–0.6 sample, the diffusion of Cu atoms into the silicon substrate was effectively suppressed. However, the copper atom diffusion into silicon can be found at Cu/Ru/NiSiy/Si sample at a temperature of 400 °C. The pure ruthenium thin film as a diffusion barrier to copper is limited. The RuCo barrier is ascertained to be a more robust barrier for copper diffusion than the Ru barrier. It can be attributed to the addition of Co in Ru thin film, which reduces the copper atoms to penetrate the silicon substrate.

The following structures are deposited under the conditions (a) glass/Ru(X nm)/Co60Fe20V20(5 nm) and (b) glass/Ta(Y nm)/Co60Fe20V20(5 nm) at room temperature (RT), where X and Y is from 5 nm to 10 nm. X-ray diffraction (XRD) patterns of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) reveal a weak crystallization at peak β-(200) as the thicknesses of Ta increase from 8 nm to 10 nm, and the patterns indicate an amorphous state as the thicknesses of all Ru films and Ta thicknesses increase from 5 nm to 7 nm. The average contact angles of glass/Ru(X nm)/Co60Fe20V20(5 nm) and glass/Ta(Y nm)/Co60Fe20V20(5 nm) are less than 90° with testing liquids deionized (DI) water and glycerol. The average contact angle of water on the surface is nearly 90 degrees, indicating it is hydrophobic. Moreover, the maximum surface energy of glass/Ru(9 nm)/Co60Fe20V20(5 nm) and glass/Ta(10 nm)/Co60Fe20V20(5 nm) are 44.5 mJ/m2 and 37.4 mJ/m2, demonstrating that the high surface energy corresponds to a strong adhesion, which can be combined with a magnetic tunneling layer of MgO or AlOx and is compatible with other semiconductor processes in magnetic recording media and photoelectric applications.

We report on the fabrication of a robust and flexible transparent electrode to replace costly and fragile indium tin oxide (ITO) used in flexible Cu(In,Ga)Se2 solar cells, composed of an aluminum doped zinc oxide (AZO)/Ag-nanowires/aluminum doped zinc oxide (AZO) (AAA herein) sandwich structure. The Ag-NWs networks form low-resistance, long-range pathways throughout the electrode that are able to maintain efficient charge carrier collection and extraction after strenuous mechanical bending. The improved durability of the AAA electrode enables our CIGS solar cells to maintain ∼95% of their initial power conversion efficiency, following 1000 bending cycles. In comparison, devices fabricated using AZO and ITO electrodes are only able to maintain ∼57 and ∼5%, respectively, due to crack formation and delamination of the films. This AAA sandwich structure electrode could therefore serve as a high-performance electrode for numerous flexible optoelectronic applications.

In this experiment, ZnO thin films were sputtered on a glass substrate by a radio frequency (RF) magnetron sputtering system at room temperature (RT). The thicknesses (t f ) of the ZnO thin film were from 500 A to 1000 A. X-ray diffraction (XRD), ultra miniature spectrometer (Spactra Smart) and four-point probe measurements were used to investigate the characteristics of ZnO thin film with various thicknesses. The results exhibited that ZnO has a wurtzite structure with a (0 0 2) texture diffraction peak in the 2 θ at 34° range. As the ZnO thin film thickness increases, the grain size becomes larger. A ZnO thin film thickness of 500 A had a transmittance maximum of about 85% and a reflectance minimum of about 15%. That means that thickness and crystallinity of ZnO play an important role in the optical results. Additionally, the four-point probe measuring resistivity ( ρ ) found that the ρ is reduced as the ZnO thickness increases because grain boundaries and the surface of thin films scatter the electrons, so thinner films have a greater resistance. Between grain size and the nanoindentation results, the decline in the hardness and Young's modulus can be reasonably concluded to be associated with an enlarged grain size, consistent with the “Hall–Petch” effect and the grain refinement mechanism. Based on the optical, electrical, and nanomechanical results, a thickness of 500 A of ZnO is suitable for photoelectrical application.

In this work, polymethylmethacrylate (PMMA) as a superior mediate for the pressure welding of silver nanowires (Ag NWs) networks as transparent electrodes without any thermal treatment is demonstrated. After a pressing of 200 kg cm-2 , not only the sheet resistance but also the surface roughness of the PMMA-mediated Ag NWs networks decreases from 2.6 kΩ sq-1 to 34.3 Ω sq-1 and from 76.1 to 12.6 nm, respectively. On the other hand, high transparency of an average transmittance in the visible wavelengths of 93.5% together with a low haze value of 2.58% can be achieved. In terms of optoelectronic applications, the promising potential of the PMMA-mediated pressure-welded Ag NWs networks used as a transparent electrode in a green organic light-emitting diode (OLED) device is also demonstrated. In comparison with the OLED based on commercial tin-doped indium oxide electrode, the increments of power efficiency and external quantum efficiency (EQE) from 80.1 to 85.9 lm w-1 and 19.2% to 19.9% are demonstrated. In addition, the PMMA-mediated pressure welding succeeds in transferring Ag NWs networks to flexible polyethylene naphthalate and polyimide substrates with the sheet resistance of 42 and 91 Ω sq-1 after 10 000 times of bending, respectively.

In this investigation, the transmittance and electrical properties of NiFe thin films were measured under three conditions. NiFe thin films were sputtered on a glass substrate with a thickness ( t f ) from 300 A to 1500 A under the following conditions: (a) substrate temperature ( T s ) maintained at room temperature (RT), (b) post-annealing at T A =150 °C for 1 h, and (c) post-annealing at T A =250 °C for 1 h. Transmission electron microscopy (TEM) demonstrated that the NiFe film yielded a strong face-centered cubic (FCC) (1 1 1) selected-area-diffraction (SAD) pattern. A spectral analyzer was utilized to measure transmittance through various thicknesses. Post-annealing treatment promoted the growth of grains, yielding a large average grain size, and therefore a small transmittance. However, electrical measurements revealed that increasing the electron mobility reduces the resistivity ( ρ ) and sheet resistance ( R s ). At a thickness of 300 A with post-annealing 250 °C, the optimal maximum transmittance is 50%; the optimal ρ is 110 μΩ cm, and the optimal R s is 13 Ω/□. Accordingly, a 300 A-thick NiFe thin film with favorable electrical and optical properties can be utilized in the components of a magneto-optical recording medium.

Ni–Fe thin films were deposited from a Ni80Fe20 target on a glass substrate by direct current magnetron sputtering. The film thickness was varied from 300 A to 1000 A and the films are formed at room temperature (RT) and annealed for 1 h at 250 °C. Plane-view high-resolution transmission electron microscopy was used to examine the microstructure of each NiFe thin film and to determine the grain sizes. Electron diffraction patterns reveal that the as-deposited and annealed NiFe thin film had a face-centered cubic NiFe. It also indicates that the crystallization of the annealed NiFe film is stronger than that of the as-deposited film. The coercivity and magnetic squareness (SQR) and remanent and saturation magnetization ratio (Mr/Ms) ratio of the in-plane magnetic hysteresis loop were measured using a superconducting quantum interference device. The coercitivity as well as the magnetic remanence properties and squareness ratio of the NiFe thin films is related to the distribution of grain sizes. The SQR value of the NiFe thin film increases upon annealing because the ordered spins in the NiFe thin film are randomized by the thermal vibration. Accordingly, Mr is increased and Ms is reduced. Hence, the SQR value decreases as the thickness of thin film increases because the refinement of the grains reduces the effective anisotropy, strengthening the ferromagnetic exchange coupling interaction.

article i nfo In this study, the structural and nanomechanical properties of Ga-doped ZnO (GZO) thin films on glass sub- strates followed by rapid thermal annealing (RTA) process were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques. The XRD results indicated that the annealed GZO thin films are textured, having a preferential crystallographic orientation along the hexagonal wurtzite (002) axis. Both the grain size and surface roughness of the annealed GZO thin films exhibit an in- creasing trend after RTA treatment. The hardness and Young's modulus of the annealed GZO thin films were measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. Furthermore, the hardness and Young's modulus were found to increase with increasing grain size when the RTA time was prolonged from 0.5 to 3 min. The deformation behavior is referred to the inverse Hall-Petch effect commonly observed in systems deformed primarily via grain boundary sliding. The sup- pression of dislocation movement-associated deformation mechanism might be arisen from strong pinning effects introduced by Ga-doping.

Effect of annealing time on structure, composition and memory characteristics of self-assembled Pt nanocrystals from reduction of an embedded PtOx ultrathin film in metal-oxide-semiconductor (MOS) memory structures were investigated in this work. The morphology and dimension of Pt nanocrystals are obviously dependent on the time of annealing in vacuum. It can be seen that the Pt nanocrystals have a narrow size distribution in the range of 2-3 nm and are well separated in SiO2 matrix annealed for 25 and 50 mins. Meanwhile, it clearly exhibits that the nanocrystals contain mainly pure Pt metal along with a slight amount of Pt silicide by X-ray photoelectron spectroscopy. The increase of Pt silicide amount with increasing the annealing time was observed and the almost saturation amount of Pt silicide was found in the device annealed for 50 mins. A significant charge storage effect, a threefold increase of stored charge density and the superior retention characteristic of the device annealed for 50 mins are achieved most likely due to the small lateral charge loss between Pt nanocrystals, and the decrease of the defect injection effect. The magnitude of the hysteresis (Vfb, hysteresis) almost remained unchanged at different frequencies, indicating that the C-V hysteresis loop results mainly from the change that is trapped inside the potential well of Pt nanocrystals in SiO2 matrix.

In this study, the effects of post-annealing on the structure, surface morphology and nanomechanical properties of ZnO thin films doped with a nominal concentration of 3 at.% Ga (ZnO:Ga) are investigated using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) and nanoindentation techniques. The ZnO:Ga thin films were deposited on the glass substrates at room temperature by radio frequency magnetron sputtering. Results revealed that the as-deposited ZnO:Ga thin films were polycrystalline albeit the low deposition temperature. Post-annealing carried out at 300, 400 and 500 °C, respectively, has resulted in progressive increase in both the average grain size and the surface roughness of the ZnO:Ga thin film, in addition to the improved thin films crystallinity. Moreover, the hardness and Young's modulus of ZnO:Ga thin films are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. The hardness and Young's modulus of ZnO:Ga thin films increased as the annealing temperature increased from 300 to 500 °C, with the best results being obtained at 500 °C.

Ta-seeded and un-seeded layers of a top-configuration Co/IrMn system were deposited onto glass substrate by DC sputtering. Three sets of deposition conditions for Co(50 A)/IrMn( t IrMn A) and Co( t Co A)/IrMn(90 A), where t IrMn = 15, 30, 60, 90, 110, and 150 A, and t Co = 15, 25, 50, 75, 100, 125, and 150 A, were: condition (a) substrate temperature ( T s ) was kept at room temperature (RT). Condition (b) T s set to RT, with in-plane magnetic field, H = 500 Oe. In condition (c), condition (b) was followed by post-deposition annealing in the magnetic field at T A = 250 °C for 1 h, then field cooled to RT. X-ray diffraction (XRD) patterns and grazing incidence scans revealed maximum IrMn (1 1 1) texture to occur for post-deposition annealed Ta seed layer samples. The IrMn (1 1 1) texture-effect significantly influences magnetic properties, including exchange-biasing field ( H ex ), interfacial energy ( J k ), and coercivity ( H c ). The Ta seed layer also significantly influences magnetic properties. Adding a Ta seed layer to the Co/IrMn system increases H ex , because of the IrMn (1 1 1) texture. For Ta-seeded Co/IrMn under condition (c), H ex tended to saturate for t IrMn ≥ 90 A. Under conditions (a) and (b), H ex decreased with increasing t IrMn for t IrMn ≥ 90 A. H ex values for all un-seeded Co/IrMn systems increased with t IrMn . J k versus t IrMn plot is proportional only to H ex in the Ta-seeded and un-seeded layers of a top-configuration Co/IrMn system, due to the interfacial energy formula, t Co is fixed, and saturation magnetization ( M s ) of the Co layer is constant. Results for the Ta-seeded system showed a strong relationship between H c and t IrMn , due to coupling-decoupling interactions between Co spin, and IrMn layers close to the Co/IrMn interface. The H ex versus t Co result shows that the H ex is proportional to (1/ t Co ). The H ex values with the Ta seed layer are almost slightly larger than those without a Ta seed-layer. The dependence of J k on t Co is similar to the trend in M s on t Co , J k tends to saturate slowly as t Co increases. Surface pinning occurred in all systems, revealing an inverse relation between H c and t Co . Removing the Ta seed-layer weakens IrMn (1 1 1) texturing, reducing H ex . The maximum observed H ex and J k values were 205 Oe and 0.11 erg/cm 2 , respectively.

A novel fully transparent and flexible impedance-type humidity sensor was fabricated by the LBL self-assembly of poly(2-acrylamido-2-methylpropane sulfonate) (PAMPS) polymer electrolyte and PAMPS thin films that were doped with salts (NaCl and K 2 CO 3 ) on a flexible substrate (polyester film; PET) substrate with a pair of comb-like aluminum-doped ZnO (AZO) transparent electrodes. The electrical properties of the LBL self-assembled PAMPS polymer electrolyte thin films were studied in detail as functions of relative humidity (RH), to elucidate the effects of the deposition concentration of PAMPS and the number of PAMPS multilayers on the sensing properties. NaCl and K 2 CO 3 were simultaneously doped into PAMPS polyelectrolyte to improve the sensing properties (sensitivity and linearity) of the transparent and flexible impedance-type humidity sensors. The transparency, flexibility, hysteresis, ambient temperature, response and recovery times and long-term stability were also studied.

The magnetostriction (λs) and tunneling magnetoresistance (TMR) of two Co/AlOx/Co/IrMn MTJ systems that were deposited on Si(1 0 0) and glass substrate were examined at RT and field-annealing with various thicknesses of AlOx. One structure was a Si(1 0 0)/Ta/Co/AlOx/Co/IrMn/Ta system, and the other was a glass/Co/AlOx/Co/IrMn system. The experimental results reveal that, in the Si(1 0 0)/Ta/Co/AlOx/Co/IrMn/Ta system, the ratio of TMR is maximal under the field-annealing condition, and is optimal at an AlOx thickness of 26 A as well as in the RT condition. EDS analysis demonstrates that, these results are related to the distribution of Co and O atoms, because the oxidation of AlOx is most extensive at a thickness of 26 A. In the glass/Co/AlOx/Co/IrMn system, λs does not significantly vary under the RT condition; however, λs is maximized (−20 ppm) by field-annealing at an AlOx thickness of 17 A. The abundance of Co and O in the system dominates the behavior of λs, according to EDS analysis. Finally, the minimum value of λs and the maximum ratio of TMR are −8 ppm and 60%, respectively, at an AlOx thickness of 26 A under the field-annealing condition.

The transparent and conductive gallium-doped zinc oxide (GZO) film was deposited on 1737F Corning glass using the radio-frequency (RF) magnetron sputtering system with a GZO ceramic target. (The Ga 2 O 3 contents are approximately 5 wt. %). In this study, the effect of the sputtering pressure on the structural, optical and electrical properties of GZO films upon the glass or polyester film (PET) substrate was investigated and discussed in detail. The GZO film was grown under a steady RF power of 400 W and a lower substrate temperature from room temperature up to 200 °C. The crystal structure and orientation of GZO thin films were examined by X-ray diffraction. All of the GZO films under various sputtering pressures had strong c -axis (002)-preferred orientation. Optical transparency was high (> 80%) over a wide spectral range from 380 nm to 900 nm. According to the experimental data, the resistivity of a single-layered GZO film was optimized at ∼ 8.3 × 10 − 4 Ω cm and significantly influenced by the sputtering pressure. In further research, the sandwich structure of the GZO film/Au metal/GZO film was demonstrated to improve the electrical properties of the single-layered GZO film. The resistivity of the sandwich-structured GZO film was around 2.8 × 10 − 4 Ω cm.

A novel fully transparent and flexible impedance-type humidity sensor was fabricated by depositing a gallium-doped ZnO (GZO) thin film on a flexible substrate (polyester film; PET) as a transparent pair of comb-like electrodes, and then coating the PET substrate with a copolymer of methyl methacrylate and [3-(methacrylamino)propyl] trimethyl ammonium chloride (MAPTAC) (poly-MMA/MAPTAC) as a sensing film. The sensor had high transmittance and good flexibility. This flexible humidity sensor also had acceptable sensitivity and a highly linear ( Y = −0.0221 X + 6.9620; R 2 = 0.9976) between logarithmic impedance (log Z ) and RH in the range 30–90% RH, low hysteresis (at 4.8% RH), a good response time (70 s), a recovery time (90 s), and long-term stability (55 days at least), measured at 1 V, 1 kHz and 25 °C. Other sensing properties such as the effects of applied voltage, frequency and ambient temperature were also studied.

The phonon–polariton behaviors of two-dimensional piezoelectric phononic crystals (PPCs) were studied using the plane wave expansion method. The governing equations combine Maxwell's equations and Newton's equations of motion. A mode-repulsion can be formed by strong coupling between electromagnetic (EM) waves and elastic waves in the vicinity of the center of the first Brillouin zone for PPC that comprises piezoelectric material and with opposite polarization in different periodically organized areas. Take a 2D ZnO PPC as a numerical example, it was decoupled into two independent groups. One refers to the mixed mode of the in-plane elastic waves and the transverse-magnetic (TM) mode EM waves. The other group refers to the mixed mode of the out-of-plane elastic waves and the transverse-electric (TE) mode EM waves. Coupling repulsion is also observed in these two groups.

The nonvolatile memory characteristics of metal?oxide?semiconductor (MOS) structures containing Au nanocrystals in the Al2O3/SiO2 matrix were studied. In this work, we have demonstrated that the use of Al2O3 as control oxide prepared by atomic-layer-deposition enhances the erase speed of the MOS capacitors. A giant capacitance?voltage hysteresis loop and a very short erase time which is lower than 1?ms can be obtained. Compared with the conventional floating-gate electrically erasable programmable read-only memories, the erase speed was promoted drastically. In addition, very low leakage current and large turn-around voltage resulting from electrons or holes stored in the Au nanocrystals were found in the current?voltage relation of the MOS capacitors.

Artificial superlattices consisting of ferroelectric BaTiO 3 (BTO), and conductive LaNiO 3 (LNO) layers were successfully prepared by rf magnetron sputtering with dual guns. The (0 0 1)-textured BTO and LNO layers were sequentially and coherently grown on (0 0 1)LNO/Pt/Ti/SiO 2 /Si substrates. The formation of superlattice structure was confirmed from the X-ray diffraction, cross-sectional image of transmission electron microscopy and depth profile of secondary ion mass spectrometer. An expansion of the c -axis of the BTO lattice was induced by the insertion of the LNO layers having a smaller lattice, and the expansion only slightly increases with the reduction of stacking periodicity of BTO layer below 12 nm. The formation of a conductive interdiffusion layer of 1.5–2.0 nm thick between the adjacent BTO and LNO layers was also found. A significant, but nearly the same extent, dielectric enhancement was achieved in the BTO/LNO superlattice with stacking periodicity of BTO ≤ 12 nm. The temperature dependence of dielectric constant also reveals the shift-up of Curie temperature in the strained BTO.

We examined two targets containing Co40Fe40B20and Co60Fe20B20. We deposited Co40Fe40B20and Co60Fe20B20monolayer thin films of various thicknesses on glass substrates through DC magnetron sputtering; the thicknesses ranged from 25 to 200 Å. The thermal properties of the Co40Fe40B20and Co60Fe20B20thin films were determined using a differential scanning calorimeter (DSC). The thermal properties included the glass transition temperature (Tg), onset crystallization temperature (Tx), and glass-forming ability, which were determined according to these values. Using the Kissinger formula revealed that the activation energy of the Co60Fe20B20with a thickness of 75 Å is the highest, implying that crystallization was the lowest and the Co60Fe20B20film showed anticrystallization properties. However, the energy of 75 Å Co40Fe40B20thin films was the lowest, which is opposite to that of Co60Fe20B20. This observation can be reasonably explained based on the concentration of Co or Fe. Therefore, a thickness of 75 Å is critical.

Tunable multilevel storage of complementary resistive switching (CRS) on single-step formation of ZnO/ZnWOx bilayer structure via interfacial engineering was demonstrated for the first time. In addition, the performance of the ZnO/ZnWOx-based CRS device with the voltage- and current-sweep modes was demonstrated and investigated in detail. The resistance switching behaviors of the ZnO/ZnWOx bilayer ReRAM with adjustable RESET-stop voltages was explained using an electrochemical redox reaction model whose electron-hopping activation energies of 28, 40, and 133 meV can be obtained from Arrhenius equation at RESET-stop voltages of 1.0, 1.3, and 1.5 V, respectively. In the case of the voltage-sweep operation on the ZnO-based CRS device, the maximum array numbers (N) of 9, 15, and 31 at RESET-stop voltages of 1.4, 1.5, and 1.6 V were estimated, while the maximum array numbers increase into 47, 63, and 105 at RESET-stop voltages of 2.0, 2.2, and 2.4 V, operated by the current-sweep mode, respectively. In addition, the endurance tests show a very stable multilevel operation at each RESET-stop voltage under the current-sweep mode.

The nonvolatile memory characteristics of metal-oxide-semiconductor structures containing Pt nanocrystals in SiO2 gate oxide were studied. The Pt nanocrystals of 2–3nm in diameter were self-assembled from reduction of an ultrathin PtOx layer embedded in the SiO2 by vacuum annealing at 425°C. A large hysteresis loop was found in the capacitance–voltage (C–V) relation indicating this significant memory effect. However, two different charge storage mechanisms were found for the Pt nanocrystals in devices with different tunnel oxide thickness. A counterclockwise C–V hysteresis was induced from substrate injection for the devices made with a thin tunnel oxide layer 2.5–5.0nm thick. Contrast, a clockwise behavior attributed to the electron transfer from charged defects in the gate oxide was found for the devices having a tunnel oxide layer 7.5nm thick. The relatively stable memory characteristics of Pt nanocrystals resulted from substrate injection were also demonstrated.

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