This letter utilizes ultrasonic spray pyrolysis (USP) to deposit Al 2 O 3 as the passivation layer of GaN light-emitting diodes (LEDs). The composition of Al 2 O 3 is analyzed by X-ray photoelectron ...spectroscopy. The refractive index and transmittance of USP-grown Al 2 O 3 are investigated. The thickness of Al 2 O 3 is determined to be 70 nm, which is close to the optimum from antireflection theorem calculation for the wavelength of 455 nm. The coverage quality and thickness are confirmed by transmission electron microscopy. The light output power (LOP) of USP-grown-Al 2 O 3 -passivated InGaN/GaN LED is improved from 321 mW to 347 mW compared with an LED without passivation. The forward voltage (V F ) and series resistance (R s ) are not subject to significant variations but the shunt resistance (R SH ) is increased after Al 2 O 3 passivation. LED chips with Al 2 O 3 and SiO 2 passivation are packaged as LED lamps. Devices passivated by USP-grown Al 2 O 3 show slightly better LOP performance than those passivated by plasma-enhanced chemical vapor deposition-grown SiO 2 .
ABSTRACT
The infectious bursal disease (IBD) causes immunosuppression in chicken of all ages and high mortality in young chicken, posing serious threat to poultry industry worldwide. One promising ...strategy for preventing this highly contagious disease is using recombinant subunit vaccine, employing VP2 subviral particles (SVP) as epitomic antigen. Analytical techniques of viral-like particles such as SDS-PAGE, western blot, or high-performance size-exclusion chromatography have been widely applied, but mostly unsatisfactory. In the present study, a simple, fast and cost-effective capillary zone electrophoresis (CZE) method with UV-detection was developed to analyze purified IBDV-SVP (expressed by Escherichia coli system) using commercial monoclonal antibody (mAb) against VP2. To find satisfying CZE conditions, injection mode, separation voltage, and separation buffer were explored. Through the modified CZE, mAb and SVP could be well separated and shown distinct peaks in the electropherogram. Furthermore, to determine the stoichiometry, the area of the mAb peak versus SVP/mAb binding ratio was plotted and indicated that 2 or 3 receptor molecules were bound per SVP. The purity and integrity of SVP and the interactions between SVP and mAb could be analyzed by the developed simple CZE-UV method in less than half hour. This CZE-UV method proved to be a valuable and useful tool in detection, characterization, and quantification of IBDV-SVP and the mAb, offering potential applications of in-process quality control of vaccine production, surveillance of serum antibody produced against IBDV infection, or vaccine immunization.
This paper proposed Al 2 O 3 deposition by ultrasonic spray pyrolysis (USP) method as an insulator layer for Al 2 O 3 /AlGaN/GaN metal-insulator-semiconductor ultraviolet photodetector (MIS-UV-PD) ...applications. The composition of USP-grown Al 2 O 3 was confirmed by X-ray photoelectron spectroscopy. The refractive index and transmittance characteristics of USP-grown Al 2 O 3 were also characterized. The Al 2 O 3 /AlGaN/GaN MIS-UV-PD performances with different Al 2 O 3 thickness (30, 20, and 15 nm) were investigated. The responsivity was 1.3 × 10 -3 /7.5 × 10 -3 /0.83 A/W, UV-to-visible rejection ratio was 2.34 × 10 3 /1.37 × 10 4 /3.18 × 10 5 , and the detectivity was 2.78 × 10 8 /1.26 × 10 9 /1.17 × 10 11 cmHz 0.5 W -1 for the MIS-UV-PD with 30-/20-/15-nm-thick Al 2 O 3 . It was found that the performances of MIS-UV-PD with 15-nm Al 2 O 3 as the insulator layer are much better than the MIS-UV-PD with 20and 30-nm Al 2 O 3 .
This paper uses H 2 O 2 oxidation technique to grow Al 2 O 3 on AlGaN/GaN heterostructure. The H 2 O 2 -grown-Al 2 O 3 is served as a sensing membrane and a surface passivation layer. The contact ...angle of the ion-sensitive field-effect transistor (ISFET) with the H 2 O 2 -grown-Al 2 O 3 is improved from 66.5° to 40.6° and this phenomenon indicates that the hydrophile characteristic is improved after the H 2 O 2 treatment. The drain-source current (IDS) is improved ~32% after the H 2 O 2 oxidation due to the passivation effect. In addition, extrinsic transconductance (gm) characteristics of the transistors are investigated. The pH sensitivity is also improved from 41.6 to 55.2 mV/pH for the ISFET with H 2 O 2 -grown-Al 2 O 3 . Furthermore, the ISFET with the H 2 O 2 treatment exhibits better transient characteristics compared with the ISFET without the H 2 O 2 treatment. The sensitivity parameter (β) and the relationship between surface potential (ψs) and pH value are investigated by theoretical calculation. The hysteresis phenomenon and the drift effect can be improved using the present H 2 O 2 -grown Al 2 O 3 as the sensing membrane and the passivation layer.
This letter reports a simple processing method for fabricating metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) by using hydrogen peroxide (H 2 O 2 ) oxidation technique. ...Aluminum oxide (AlO x ) was formed on the surface of the AlGaN barrier as the gate dielectric of the MOS-gate structure. By using the capacitance-voltage measurement, the dielectric constant (κ) of AlO x was determined to be 9.2. The present MOS-HEMT has demonstrated enhanced saturation drain current density at V GS = 0 V (I DSS0 ) of 552.3 mA/mm, maximum extrinsic transconductance (g m, max ) of 136 mS/mm, wide gate voltage swing of 2.9 V, and two-terminal gate-drain breakdown/turn-on voltages (BV GD /V on ) of -132.2/1.82 V.
This brief reports, for the first time, an oxide passivated AlGaN/GaN high electron mobility transistor by using the hydrogen peroxide (H 2 O 2 ) treatment. Characterizations by using electron ...spectroscopy for chemical analysis and transmission electron microscopy have been performed to verify the formation of surface oxide on the AlGaN barrier layer. The present design has demonstrated superior improvements of 41% in the maximum drain/source current density I DS,max ; 39% in the drain/source saturation current density at zero gate bias I DSSO , 47% in the maximum extrinsic transconductance g m,max , 53.2% in the two-terminal gate/drain breakdown voltage BV GD 36% in the cutoff frequency f T , and 20% in the maximum oscillation frequency f max , as compared with an unpassivated conventional device.
This letter reports, for the first time, the Al 2 O 3 -passivated AlGaN/GaN high electron mobility transistors (HEMTs) by using the nonvacuum ultrasonic spray pyrolysis deposition (USPD) technique. ...The Al 2 O 3 was devised as the surface passivation layer to effectively suppress leakage current and to reduce RF drain current collapse. The surface oxide has been characterized by using electron spectroscopy for chemical analysis, energy-dispersive X-ray spectroscopy, and transmission electron microscopy (TEM). With respect to an unpassivated device, the Al 2 O 3 -passivated HEMT has demonstrated superior improvements of 24.2% in maximum drain-source current (I DS,max ), 33.6% in maximum extrinsic transconductance (g m,max ), 46.8% in two-terminal breakdown voltage (BV GD ), and 45.3% in three-terminal off-state breakdown voltage (BV off ). The corresponding improvements achieved are 9.1%, 16.1%, 61.3%, and 55.7% for I DS,max, gm,max, BV GD , and BV off , respectively, as compared with passivation in Si 3 N 4 HEMTs. Besides, reduced interface density (Dit) and about two-order decreases in the leakage current are also achieved in the Al 2 O 3 -MOS diode using USPD with respect to a Si 3 N 4 -MIS diode.
Decarboxylation of oleic acid without hydrogen was carried out using hydrotalcites with three different MgO contents (30, 63 and 70
wt%). Effect of MgO content in hydrotalcites and reaction ...temperatures on the decarboxylation performance in terms of oleic acid conversion and product distribution were investigated. Also, the stability of hydrotalcites in the decarboxylation reaction was examined by XRD analysis. It was found that MgO content in hydrotalcites and reaction temperature played key roles in decarboxylation reaction. At lower reaction temperature and MgO concentration in hydrotalcite, the conversion of oleic acid scarcely occurred. On the other hand, oleic acid conversions were more than 98% and the oxygen content in the reaction product was less than 1
wt% in the case of decarboxylation with MG63 (63% of MgO) and MG70 (70% of MgO) at 673
K. Solid-like products were formed in the reaction at 623
K, resulting from saponification of oleic acid and MgO. Considering conversion and the stability of catalysts, higher temperature, 673
K, is preferred to prevail decarboxylation over saponification. It was confirmed that most of the oxygen molecules in oleic acid were removed in the form of CO
2 from the elemental and FT-IR analysis of the liquid products. Pure hydrocarbons such as octane, nonane and heptadecene were produced in the case of MG63 and MG70 at 673
K while decanoic acid was additionally observed in case of blank test and MG30 catalyst at 673
K.
The metabolic profiles of Panax quinquefolius and its associated therapeutic values are critically affected by the repetitious steaming times. The times-dependent steaming effect of P. quinquefolius ...is not well-characterized and there is also no official guideline on its times of steaming. In this paper, a UPLC-Q-TOF-MS/MS method was developed for the qualitative profiling of multi-parametric metabolic changes of raw P. quinquefolius during the repetitious steaming process. Our method was successful in discriminating the differentially multi-steamed herbs. Meantime, the repetitious steaming-inducing chemical transformations in the preparation of black American ginseng (American ginseng that was subjected to 9 cycles of steaming treatment) were evaluated by this UPLC-Q-TOF-MS/MS based chemical profiling method. Under the optimized UPLC-Q-TOF-MS/MS conditions, 29 major ginsenosides were unambiguously identified and/or tentatively assigned in both raw and multi-steamed P. quinquefolius within 19 min, among them 18 ginsenosides were detected to be newly generated during the preparatory process of black American ginseng. The mechanisms involved were further deduced to be hydrolysis, dehydration, decarboxylation and addition reactions of the original ginsenosides in raw P. quinquefolius through analyzing mimic 9 cycles of steaming extracts of 14 pure reference ginsenosides. Our novel steaming times-dependent metabolic profiling approach represents the paradigm shift in the global quality control of multi-steamed P. quinquefolius products.
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