Effects of post-deposition annealing ambient on band alignment of RF magnetron-sputtered Y2O3 film on gallium nitride

The effects of different post-deposition annealing ambients (oxygen, argon, forming gas (95% N₂ + 5% H₂), and nitrogen) on radio frequency magnetron-sputtered yttrium oxide (Y₂O₃) films on n-type gallium nitride (GaN) substrate were studied in this work. X-ray photoelectron spectroscopy was utilized to extract the bandgap of Y₂O₃ and interfacial layer as well as establishing the energy band alignment of Y₂O₃/interfacial layer/GaN structure. Three different structures of energy band alignment were obtained, and the change of band alignment influenced leakage current density-electrical breakdown field characteristics of the samples subjected to different post-deposition annealing ambients. Of these investigated samples, ability of the sample annealed in O₂ ambient to withstand the highest electric breakdown field (approximately 6.6 MV/cm) at 10⁻⁶ A/cm² was related to the largest conduction band offset of interfacial layer/GaN (3.77 eV) and barrier height (3.72 eV).     

Nonionic Mixed Surfactant Stabilized Water-in-Oil Microemulsions for Active Ingredient In Vitro Sustained Release

Olive oil is an excellent dispersing medium for water‐in‐oil microemulsions as it helps hydrate the skin and enhances the release of the active ingredients. In this study, mixed surfactants containing Span^® 80 with varied Tween^® series at 1:1 ratio were prepared with olive oil and water to produce water‐in‐oil microemulsions. The microemulsions were used to study the in vitro release of the active ingredients with different water solubilities. A microemulsion olive oil/water/mixed surfactant (56:4:40 by weight) was selected from the constructed phase diagram for further physical characterization. The analysis showed that the microemulsion composed of Span^® 80 and Tween^® 80 (ST80) was the most suitable surfactant combination. Equal amounts of ascorbic acid, caffeine and lidocaine were solubilized in ST80 microemulsions to study their release rate. Physical evaluation of ST80 microemulsions incorporating the active ingredients showed no apparent change compared to the ST80 microemulsion alone. The in vitro release study showed that the rate of active ingredients released from the microemulsion into the receptor chamber depends on their hydrophobicity, whereby lidocaine and caffeine were fivefold and twice as fast, respectively, with respect to ascorbic acid. ST80 microemulsions show constant rate of active ingredient release, demonstrating the sustained release properties of the system.     

Thermal oxidation and nitridation of sputtered Zr thin film on Si via N2O gas

Formation of ZrO₂ by simultaneous thermal oxidation and nitridation in nitrous oxide of sputtered Zr on Si substrate is reported here for the first time. Sputtered Zr on Si substrate and followed by oxidation and nitridation in nitrous oxide ambient at 700 °C for various durations (5-20 min) have been systematically investigated. The structural and chemical properties of the samples were examined. Chemical depth profiles of the samples have been evaluated by X-ray photoelectron spectroscopy. Stoichiometric Zr-O (ZrO₂) and its interfacial layer consisted of mixed sub-stoichiometric Zr-O, Zr-N, Zr-Si-O, Si-N, and/or Si-O-N phases were identified. A possible model related to the oxidation and nitridation mechanisms has been proposed and explained. Supportive results related to the model were obtained by energy filtered transmission electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier Transform infrared analysis.     

Component commonality in assembled-to-stock systems

This paper quantifies the impact of component sharing in a two-echelon assembled-to-stock system consisting of several common components and end-products. Whereas there is a benefit from risk pooling when component sharing is allowed, there is also a component-mismatch problem due to the demand uncertainty for end-products. We study these conflicting effects by comparing a particular component sharing policy, namely the equal-fractile allocation policy, with a make-to-stock system which does not allow the allocation of common components. The probabilistic analysis shows that when each type of component is shared by at least two end-products, the equal-fractile allocation policy will always help to reduce the safety stock required to be held at a sufficiently high service level. We also look at a special scenario of the equal-fractile allocation policy which takes into account inventory cost considerations. We show that this problem can be formulated as a newsvendor problem.     

Development and application of an integrated framework for small UAV flight control development

This paper presents an integrated framework for small Unmanned Aerial Vehicle (UAV) flight control development. The approach provides a systematic procedure for flight control design process with a set of design tools that enables control engineers to rapidly synthesize, analyze and validate a candidate controller design. A model-based environment integrated with control synthesis, off-line and real-time simulation is developed for flight control synthesis, analysis and testings. The effectiveness of the proposed integrated framework is demonstrated by applying the framework approach to a small UAV testbed. Software-in-the-loop, processor-in-the-loop and flight testings are conducted with the synthesized controller implemented. Closed-loop performance and robustness results obtained are presented.     

Deposition and post-deposition annealing of thin Y2O3 film on n-type Si in argon ambient

Thin (∼5.0 nm) Y₂O₃ films were deposited on n-type Si (1 0 0) substrate using RF magnetron sputtering. Detailed studies on the effects of post-deposition annealing (PDA) temperatures (400, 600, 800, and 1000 °C) in argon ambient on these films were performed by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscopy, and atomic force microscopy. Interfacial layer (IL) of SiO₂ in between Y₂O₃ and the Si substrate for sample annealed from 400 to 800 °C had been suggested from the results of FTIR. As for sample annealed at 1000 °C, presence of IL might consist of both Y₂Si₂O₇ and/or SiO₂ through the detection of Y₂Si₂O₇ compound and Si–O chemical bonding from XRD and FTIR analysis, respectively. For as-deposited sample, no detectable chemical functional group at the IL was recorded. Electrical characteristics of the Y₂O₃ films were acquired by fabricating metal-oxide–semiconductor capacitor as test structure. An improvement in the breakdown voltage (V_B) and leakage current density (J) was perceived as the PDA temperature increased. Of the PDA samples, the attainment of the lowest effective oxide charge, interface trap density, total interface trap density, and the highest barrier height at 1000 °C had contributed to the acquisition of the highest V_B and lowest J.     

Crystallization kinetics of amorphous Ga-Sb films extended for phase-change memory

Performance of phase-change materials based on Ga-Te-Sb was found getting better with decreasing Te content in our earlier studies. We concerned much properties of Te-free, Sb-rich binary Ga-Sb, which has been known to possess extremely fast crystallization behavior. Non-isothermal and isothermal crystallization kinetics of amorphous Sb-rich Ga-Sb films were explored by temperature dependent electrical resistance measurements. The crystallization temperature (183 to 261 degrees C) increases with decreasing Sb content (91 to 77 at%). The activation energy and rate-factor vary with Sb contents and reach the maximum at Ga19Sb81. The kinetic exponent is smaller than 1.5 at Sb < 85 at% denoting that the mechanism is one-dimensional crystal-growth from nuclei. The temperature corresponding to 10-year data-retention, evaluated from films, is 180 degrees C (Ga19Sb81) and 137 degrees C (Ga13Sb87), respectively. We verified memory performance using test-devices made of Ga16Sb84 working at voltages with 100 ns pulse-width.     

Influence of interface traps and surface mobility degradation on scanning capacitance microscopy measurement

Although scanning capacitance microscopy (SCM) is based on the MOS capacitance theory, the measurement frequency is 915-MHz instead of 100 kHz to 1 MHz in conventional MOS capacitance-voltage measurement. At this high frequency, the reactance of the probe tip-to-substrate capacitance can become smaller than the series resistance of the substrate inversion layer, particularly when the surface mobility is degraded. The response of the oxide-silicon interface traps to SCM measurement is also different due to the use of a 10-kHz signal to determine dC/dV. In this paper, we compare experimental and simulation data to demonstrate the effects of interface traps and surface mobility degradation on SCM measurement. Implications on the treatment of SCM data for accurate dopant profile extraction are also presented.     

Development of a probiotic delivery system from agrowastes, soy protein isolate, and microbial transglutaminase

Abstract: Probiotic delivery system was developed via the use of microbial transglutaminase (MTG) cross‐linked soy protein isolate (SPI) incorporated with agrowastes such as banana peel (BE), banana pulp (BU), and pomelo rind (PR). Inoculums of Lactobacillus bulgaricus FTDC 1511 were added to the cross‐linked protein matrix. The incorporation of agrowastes had significantly (P < 0.05) reduced the strength, pH value, and the lightness of the SPI gel carriers, while sodium dodecyl sulfate‐polyacrylamide gel electrophoresis profiles revealed that the occurring cross‐links within the SPI gel carriers were attributed to the addition of MTG. Scanning electron microscope micrographs illustrated that SPI carriers containing agrowastes have exhibited a less‐dense protein matrix. All the SPI carriers possessed maximum swelling ratio at 4 to 4.5 within 15 min in simulated gastric fluid (SGF), whereas the maximum swelling ratios of SPI/BE, SPI/BU, and SPI/PR were higher compared to that of control in simulated intestinal fluid (SIF). Additionally, SPI carriers in SGF medium did not show degradation of structure, whereas a major collapse of network was observed in SIF medium, indicating controlled‐release in the intestines. The addition of agrowastes into SPI carriers led to a significantly (P < 0.0001) lower release of L. bulgaricus FTDC 1511 in SGF medium and a higher release in SIF medium, compared to that of the control. SPI carriers containing agrowastes may be useful transports for living probiotic cells through the stomach prior to delivery in the lower intestines. Practical Application: Agrowastes could be utilized as a new probiotic carrier for enhanced gastrointestinal transit and during storage. This also reduces the amount of agrowastes accumulated.