The effect of hot carriers on the characteristics of via-contact-type amorphous In-Ga-Zn-O thin-film transistors is investigated. After hot-carrier stress, the gate-to-source capacitance curve shows ...a two-stage rise while the gate-to-drain capacitance curve exhibits parallel shifts. It is found that hot electrons are injected into the etch-stop layer or trapped at the InGaZnO/etch-stop layer interface below redundant drain electrode. This is further verified by measuring the characteristic capacitance curve with a positive top gate bias.
Reverse-scored items on assessment scales increase cognitive processing demands and may therefore lead to measurement problems for older adult respondents. In this study, the objective was to examine ...possible psychometric inadequacies of reverse-scored items on the Center for Epidemiologic Studies Depression Scale (CES-D) when used to assess ethnically diverse older adults. Using baseline data from a gerontologic clinical trial (n = 460), we tested the hypotheses that the reversed items on the CES-D (a) are less reliable than nonreversed items, (b) disproportionately lead to intraindividually atypical responses that are psychometrically problematic, and (c) evidence improved measurement properties when an imputation procedure based on the scale mean is used to replace atypical responses. In general, the results supported the hypotheses. Relative to nonreversed CES-D items, the 4 reversed items were less internally consistent, were associated with lower item-scale correlations, and were more often answered atypically at an intraindividual level. Further, the atypical responses were negatively correlated with responses to psychometrically sound nonreversed items that had similar content. The use of imputation to replace atypical responses enhanced the predictive validity of the set of reverse-scored items. Among older adult respondents, reverse-scored items are associated with measurement difficulties. It is recommended that appropriate correction procedures such as item readministration or statistical imputation be applied to reduce the difficulties. (Contains 1 table and 1 footnote.)
A tantalum pentoxide‐based (Ta2O5‐based) micro‐ring all‐optical modulator was fabricated. The refractive index inside the micro‐ring cavity was modified using the Kerr effect by injecting a pumped ...pulse. The transmittance of the ring resonator was controlled to achieve all‐optical modulation at the wavelength of the injected probe. When 12 GHz pulses with a peak power of 1.2 W were coupled in the ring cavity, the transmission spectrum of the Ta2O5 resonator was red‐shifted by 0.04 nm because of the Kerr effect. The relationship between the modulation depth and gap of the Ta2O5 directional coupler is discussed. An optimized gap of 1100 nm was obtained, and a maximum buildup factor of 11.7 with 84% modulation depth was achieved. The nonlinear refractive index of Ta2O5 at 1.55 μm was estimated as 3.4 × 10−14 cm2/W based on the Kerr effect, which is almost an order of magnitude higher than that of Si3N4. All results indicate that Ta2O5 has potential for use in nonlinear waveguide applications with modulation speeds as high as tens of GHz.
Because of the Ta2O5‐based modulator's micro‐ring cavity structure, the ultrafast refractive index change induced by pump beam is used to control probe beam at a speed of tens of GHz. The fabrication processes for Ta2O5 devices are CMOS‐compatible, and Ta2O5‐based nonlinear optical applications can be integrated into Si photonics.
This paper investigates degradation behavior induced by the self-heating effect for InGaZnO (IGZO) thin-film transistors (TFTs). Both the surrounding oxide and other thermal insulating materials, as ...well as the low thermal conductivity of the InGaZnO layer itself, cause the self-heating effect in InGaZnO TFTs. The heated channel layer enhances the threshold voltage shift, and the evolution of threshold voltage shift is found to be dominated by charge-trapping effects. Moreover, a nonuniform distribution of channel carrier concentration leads to an uneven temperature distribution throughout the IGZO active layer, which results in the asymmetrical degradation behavior after the self-heating operation. Further verifications indicate that the degree of the threshold voltage shift is only dependent on stress power, regardless of stress Vg , Vd , and channel length. Further, two-stage dependence of the threshold voltage shift on dynamic stress frequency is found.
In this letter, we fabricated resistance random access memory in a Pt/GaOx/TiN structure with a bipolar resistance switching characteristic and a bistable resistance ratio of about two orders by I - ...V sweeping. In order to increase the oxygen ion quantity in the gallium oxide layer, the proposed sample was sputtered in a mixed ambient of Ar and oxygen, and the resistance ratio was enhanced by 2.5 orders. In addition to the resistance ratio, set voltage distribution statistics show that the stability of gallium oxide sputtered in mixed Ar and oxygen gas was better than standard Ar-only sample.
▶ High hydrophilic/hydrophobic contrast surfaces on PET substrates. ▶ This was accomplished using a mask and by controlling the distance of the mask to the substrate in SF6 plasma. ▶ The best ...contract in water contact angle obtained from the treated PET samples was larger than 100°.
High hydrophilic/hydrophobic contrast surfaces on polyethylene terephthalate (PET) substrates were formed by shadow mask technique in electron cyclotron resonance generated sulfur hexafluoride plasma atmosphere. The X-ray photoelectron spectroscopy (XPS) analyses indicate that the unmasked PET surfaces contained a high proportion of the CF2–CF2 groups, and therefore were hydrophobic with large water contact angle. However, the surface wettability was found to increase drastically on the masked PET surfaces. This could be resulted from a mass of COF (acid fluoride) compounds observed by XPS on the masked film surfaces. The COF compounds could react with atmospheric moisture to form –COOH groups, which in turn increased the surface wettability. In addition, the surface wetting property of the masked areas was found to change significantly with the plasma treatment time, the mask-to-substrate distance and the storage time after the treatment. The best contract in water contact angle obtained from the treated PET samples was larger than 100° after 168h of storage.
We investigate the abnormal current-voltage (C-V) hump effect of p-type low-temperature polysilicon (LTPS) thin-film transistors (TFTs) which have undergone high current operations. Experimental ...results indicate localized electron trapping in the gate insulator (GI), which is carried out near the drain. The ON-current (ION) enhancement is due to the reduction of effective length, and the O FF -current (I OFF ) decrease as the electron tunneling path distance increases. These can be observed after hot carrier stress in current characteristics. The C-V measurements demonstrate that the threshold voltage (V th ) shift is associated with the gate length. In addition, capacitance-voltage measurements also show that this localized trapping region remains the same in length, regardless of channel length. Hence, a model is proposed to explain how the electric field, which is gate length-dependent, affects the source side of the device, and then lowers the source barrier height. This leads to bulk leakage, which causes the subthreshold swing degradation at device scale down.
This study investigates bipolar resistance switching memory in a fabricated Pt/GaOx/TiN device. Gallium oxide sputtered in ambient Ar shows a change in resistance ratio of two orders of magnitude. ...The enhancement of resistance ratio is also observed in the gallium oxide layer when deposited in ambient Ar/O2. The X-ray photoelectron spectroscopy analysis shows that this gallium oxide in ambient Ar/O2 can reduce the number of defects and enhance the stability of switching behavior. An analysis of current transport mechanism in the high resistance state indicates that the larger effective thickness can be attributed to the higher oxygen concentration, and can increase the resistance value of the high resistance state.
► Study on the switching mechanisms in a Pt/GaOx/TiN device ► Pt/GaOx/TiN exhibits bipolar resistive switching behavior. ► The bipolar behavior originates from conduction associated to oxygen vacancies. ► Additional oxygen can enhance the effective thickness.
This letter systematically investigates the mechanism of gate-induced floating-body effect (GIFBE) in advanced partially depleted silicon-on-insulator metal-oxide-semiconductor field-effect ...transistors. Based on different operation conditions, we found that the hole current collected by the body terminal is strongly dependent on electrons in the inversion layer under a source/drain ground. This implies that GIFBE can be attributed to anode hole injection (AHI) rather than the widely accepted mechanism of electron valence band tunneling. Moreover, GIFBE was also analyzed as a function of temperature. The results provide further evidence that the accumulation of holes in the body results from the AHI-induced direct tunneling current from the gate.
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