Texting versus talking: An exploration in telecommunication language

Prior research on text messaging has focused on its elliptical nature (e.g., acronyms, etc.). In contrast, the purpose of this research was to conduct an investigation of the type of words that tend to occur in text messages. Participants (N = 224) retrieved their most recent text messages which were then analyzed with the Linguistic Inquiry and Word Count (LIWC) program (  and ) and compared with parallel analyses of randomly selected telephone conversations (N = 214). The results indicated numerous linguistic differences between text messages and telephone conversations. The former were linguistically simpler, more personal and more affective than the latter. Overall, the results further our understanding of the linguistic dimensions of this relatively new form of communication.     

"Have Fun While You Can,""You're Only as Old as You Feel," and "Don't Ever Get Old!": An Examination of Memorable Messages About Aging

Previous research has indicated memorable messages are important because they provide socializing functions by influencing cognitions and behaviors. This study examined the content, context, and structure of memorable messages about aging from the receiver's perspective. Message senders were older than receivers and tended to be female and family members. Senders usually were perceived to have benevolent motives. Messages did not tend to be rule-structured. Message content pertained to topics like the benefits of aging; aging as a natural, inevitable process; the need to enjoy life; and losses associated with aging. Message effects included viewing aging more positively, viewing aging more negatively, resolving to enjoy life or take better physical care of oneself, and changing relationships with others.     

New design of RF rectifier for passive UHF RFID transponders

A novel diode-connected MOS transistor for ultra-high-frequency (UHF) micro-power rectifiers was presented, and a high efficiency N-stage charge pump voltage rectifier based on this new diode-connected MOS transistor was designed and implemented. The new diode-connected MOS transistor and the rectifier are designed and fabricated in SMIC 0.18-μm 2P3M CMOS embedded EEPROM process. The structure design of the new diode achieved 315 mV turn-on voltage, and 415 nA reverse saturation leakage current. Compared with traditional rectifier, the rectifier using the presented diode-connected MOS has higher power conversion efficiency (PCE), higher output voltage and smaller ripple coefficient. When the RF input is a 900-MHz sinusoid signal with the amplitude ranging from 0.8 to 1.8 V, PCEs of the charge pump rectifier with only 3-stage are more than 30%, and the maximum output voltage is 5.02 V, and its ripple coefficients are less than 1%.     

Design of a tunable frequency CMOS fully differential fourth-order Chebyshev filter

A new fully differential amplifier and a fully differential R-MOSFET-C fourth-order Chebyshev active lowpass filter employing passive resistors and current-steering MOS transistors as variable resistors are proposed. The implementation relies on the tunability of current-steering MOS transistors operating in the triode region which counteract the deviation of resistors in integrated circuit manufacturing technology in order that the cutoff frequency of Chebyshev active filter can be realized accurately tunable. The amplifier is not only with voltage common-mode negative feedback (VCMFB), but also with current common-mode negative feedback (CCMFB), which will benefit for the stability of its DC operating point. A cutoff frequency of 138 kHz fourth-order Chebyshev lowpass filter was designed and fabricated using 3.3 V power supply and 0.35 μm CMOS technology. Chip test results demonstrate better than −68 dB THD with 70 kHz, 2.0V_pp signal, frequency turning range of more than 14,000 from 3 Hz to 420 kHz, chip area of 0.36 mm² and power consumption of 16 mW.     

Finite element analysis of low temperature thermal nanoimprint lithography using a viscoelastic model

Nanoimprint lithography (NIL) is an emerging technology that enables cost-effective and high-throughput nanofabrication. Nevertheless, there are some disadvantages to this method, especially for thermal NIL. A major disadvantage of thermal NIL is the thermal cycle, which requires a significant amount of processing time and limits the throughput. One method to overcome this disadvantage is to reduce the processing temperature. Accordingly, it is necessary to determine the effects on the processing parameters for thermal NIL at reduced temperatures and to optimize the parameters. This requires a clear understanding of the behavior of the polymer material during the thermal NIL process. This work focuses on a temperature range of T_g < T < T_g + 40 °C, in which the polymer displays a semi-molten state behavior; this temperature range is lower than conventionally used for thermal NIL. To understand how the processing conditions of temperature, pressure, pattern density, and initial thickness of the polymer resist are related to the quality of a nanoimprinted pattern, simulations of thin polymer films squeezing into nanocavities during thermal NIL were performed using a two-dimensional viscoelastic finite element analysis taking into account stress relaxation behaviors.     

A highly miniaturized LTCC dual-band UWB filter using independent transmission zeros and lowpass filters

In this paper, a compact dual-band ultra-wideband (UWB) filter has been newly designed and fabricated for 3.1–4.75 GHz and 6.0–8.5 GHz UWB system applications by embedding all passive lumped elements into low temperature co-fired ceramic (LTCC) substrate. In order to reduce its size/volume and prevent parasitic electromagnetic (EM) coupling between the embedded passive elements, it was newly designed by using a modified 3rd order Chebyshev filter topology and J-inverter transformation technology. Moreover, in order to completely reject the wireless local area network (WLAN) bands of 2.4 GHz and 5.15 GHz, an independent transmission zeros technology was applied. For forming the higher passband, lowpass filters were also applied with two LC resonant circuits by using roll-off characteristics by independent transmission zeros. The measured insertion losses in the lower and upper passbands were better than 2.5 and 2.3 dB, respectively. Return loss and group delay were better than 8 dB and 0.61 ns, respectively in all the passbands. Independent transmission zeros that occurred at 5.17 and 5.42 GHz provided suppression of 22 dB at the WLAN band. The size/volume of the fabricated LTCC dual-band UWB filter was 3.65×2.35×0.65 (H) mm³.     

Experiments and simulation of the diffusion and activation of the n-type dopants P, As, and Sb implanted into germanium

The effects of implant dose and annealing conditions on the diffusion, activation, and out-diffusion of the typical n-type dopants in germanium (phosphorus, arsenic, antimony) were studied. First, short annealing times were used to limit the diffusion of dopants and to match the conditions needed for the realization of shallow junctions. Sb is not well suited to achieve high activation levels because honeycomb voids can already form at doses of 3 × 10¹⁴ cm⁻². Of the other two, P is a better candidate than As because it was possible to maximize the activation level to up to about 4.5 × 10¹⁹ cm⁻³ without noticeable diffusion. This absolute value has only a limited accuracy, though, since the mobility models available in literature lead to values which differ by more than one order of magnitude. Longer annealing times were then used to study the redistribution of the dopants. For P, a model based on migration predominantly via complexes with doubly negatively charged vacancies and dopant loss was implemented which allowed the simultaneous simulation of our experimental profiles with one set of parameters. The extracted diffusion coefficient with an activation energy of 2.2 eV is comparable to the results obtained in previous studies. No noticeable P clustering was observed in these experiments. The model was then adapted to simulate the redistribution of As and Sb. For Sb, clustering is apparent in the diffusion profiles and has to be taken into account in the simulations.     

Optical properties of cubic SiC grown on Si substrate by chemical vapor deposition

A series of 3C-SiC films with varied film thickness up to 17 μm have been grown on Si(1 0 0) by chemical vapor deposition, and studied by photoluminescence, Raman scattering, Fourier transform infrared transmission and reflectance measurements. Typical key behaviors on these optical spectra are investigated. Thinner (<3 μm) films have their optical spectral features, mainly associated with defects. High quality of single crystalline cubic SiC materials can be obtained from thicker (>10 μm) films, evidenced by optical spectra. There exists a tensile stress in the 3C-SiC film grown on Si, affecting greatly the optical features. Its measurements have leaded to a formulas on two deformation potentials, a and b.     

Enhanced performance of dye-sensitized solar cells with novel 2,6-diphenyl-4H-pyranylidene dyes

Novel 2,6-diphenyl-4H-pyranylidene derivatives were designed and synthesized as dyes for dye-sensitized solar cells (DSSC). Dyes 2a, b with a phenyl substituent showed high DSSC energy conversion efficiencies of 5.3% (J_sc = 10.3 mA/cm², V_oc = 0.72 V, FF = 0.72) and 4.7% (J_sc = 8.9 mA/cm², V_oc = 0.73 V, FF = 0.72) at 100 mW/cm² under simulated AM 1.5 G solar light conditions. These values are twice better than that of dye 1 without the phenyl substituent under the same conditions. Both the photocurrent density (J_sc) and open circuit voltage (V_oc) of DSSCs based on dyes 2a, b are increased compared with 1. It can be attributed to their twisted structures, absorption abilities and proper energy levels. This result shows that the tetraphenylpyranylidene is a promising electron-donor unit for high-efficiency DSSCs.     

Control of threshold voltage and improved subthreshold swing in enhancement-mode InGaP/InGaAs metal-oxide-semiconductor pseudomorphic high-electron-mobility transistor

The InGaP/InGaAs metal-oxide-semiconductor pseudomorphic high-electron-mobility transistor (MOS-PHEMT) with an oxidized GaAs gate by liquid phase oxidation (LPO) is demonstrated. With the help of the LPO, the threshold voltage (V_th) can be shifted positively to 0.07 V, and enhancement-mode MOS-PHEMT is fabricated. The device with a gate metal of 1 × 100 μm² shows a maximum transconductance of 171 mS/mm at V_DS = 5 V and a maximum drain current density of 182 mA/mm at V_GS = 2 V. It also exhibits a lower leakage current and an improved subthreshold swing compared to the referenced Schottky-gate InGaP/InGaAs PHEMT.     

A CMOS linear-in-dB VGA and AGC loop for telecommunication applications

In this paper, an Automatic Gain Control (AGC) loop which is based on a linear-in-dB Variable Gain Amplifier (VGA) is proposed. The VGA structure is based on simple nMOS differential pairs with variable tail currents. The linear-in-dB gain tuning schema is designed using a novel exponential current generator which also offers temperature compensation of the VGA's gain. The gain of the VGA is tuned by a control voltage with gain range about 28 dB with ±1 dB linearity error. The worst cases of the VGA gain, over process and temperature corners, are ±1.54 dB and ±2.45 dB for maximum and minimum gain setting, respectively. The proposed implementation is designed in a CMOS 90 nm triple-well process with 1.2 V supply voltage.     

Design and fabrication of 94 GHz MMIC single balanced resistive mixer without IF balun

In this paper, a 94 GHz microwave monolithic integrated circuit (MMIC) single balanced resistive mixer affording high LO-to-RF isolation was designed without an IF balun. The single balanced resistive mixer, which does not require an external IF balun, was designed using a 0.1 μm InGaAs/InAlAs/GaAs metamorphic high electron mobility transistor (HEMT). The designed MMIC single balanced resistive mixer was fabricated using the 0.1 μm MHEMT MMIC process. From the measurement, conversion loss of the single balanced resistive mixer was 14.7 dB at an LO power of 10 dBm. The P_1 dB (1 dB compression point) values of the input and output were 10 dBm and −5.3 dBm, respectively. The LO-to-RF isolation of the single balanced resistive mixer was −35.2 dB at 94.03 GHz. The single balanced resistive mixer in this work provided high LO-to-RF isolation without an IF balun.     

Simulation and fabrication of high voltage AlGaN/GaN based Schottky diodes with field plate edge termination

In this paper, we report the breakdown voltage (BV) of AlGaN/GaN based Schottky diodes with field plate edge termination. Simulation and fabrication of AlGaN/GaN Schottky diodes were carried out. The simulations were performed using the commercial 2-D device simulator DESSIS. From the simulations, it is found that for a given gate-Ohmic distance (L_gd) of 10 μm, 2DEG of 1 × 10¹³ cm⁻² and field plate length (L_FP) of 2.5 μm, highest BV can be obtained for a silicon nitride thickness of 8000 Å and this BV value is more than 5 times that for a Schottky diode without field plate. The breakdown voltages were also simulated for different field plate lengths. The BV values obtained on the fabricated Schottky diodes are compared with the simulation data and the experimental results follow the trend obtained from the simulation. Simulations were also carried out on a Schottky diode with field plate placed over a stepped insulator with L_gd = 10 μm, L_FP = 5 μm and 2DEG = 1 × 10¹³ cm⁻² and the obtained BV values are about 7 times that without field plate.     

Top injection reactor tool with in situ spectroscopic ellipsometry for growth and characterization of ALD thin films

Ta-N based thin films were grown by thermal atomic layer deposition (ALD) with an alternating supply of the reactant source TBTDET (tert-butylimidotris(diethylamido)tantalum) and NH₃ (ammonia). The films were deposited using a newly designed and constructed atomic layer deposition prototype tool combined with several in situ metrology. It was observed that thin films were successfully deposited on a 300 mm Wafer with a saturated growth rate of approximately 0.55 Å/cycle at 270 °C. The as deposited films resulted in the formation of Ta(C)N consisting of 38 at% Ta, 32 at% N and 10 at% C. With in situ spectroscopic ellipsometry (SE) the growing behaviour of the film was investigated and compared to atomic force microscopy (AFM) images.     

Temperature dependent current-voltage characteristics of the Zn/ZnO/n-Si/Au-Sb structure with ZnO interface layer grown on n-Si substrate by SILAR method

This is the first time; it was employed Successive Ionic Layer Adsorption and Reaction (SILAR) method in order to prepare Zn/ZnO/n-Si/Au-Sb sandwich structure. The ZnO interface layer was directly formed on n-type Si substrate using SILAR method. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies were showed that the film is covered well on n-type Si substrate and have polycrystalline structure. An Au-Sb electrode was used as an ohmic contact. The Zn/ZnO/n-Si/Au-Sb sandwich structure demonstrated clearly rectifying behavior by the current-voltage (I-V) curves studied at room temperature. The sample temperature effect on the current-voltage (I-V) characteristics of Zn/ZnO/n-Si/Au-Sb structure was investigated in temperature range 80-320 K by steps of 20 K. The parameters such as barrier height, ideality factor and series resistance of this structure were calculated from the forward bias I-V characteristics as a function of sample temperature. It was seen that the ideality factor and series resistance were decreased; the barrier height were increased with increasing temperature. The experimental values of barrier height and ideality factor for this device were calculated as 0.808 eV and 1.519 at 320 K; 0.220 eV and 4.961 at 80 K, respectively. These abnormal behaviors can be explained by the barrier inhomogeneities at the metal-semiconductor (M-S) interface.     

Miniature SAW device using MEMS technology

A miniature SAW device is designed and fabricated at 1 GHz for wireless communication system. A 5 μm thin film of ZnO is successfully deposited using RF sputtering technique on plasma-enhanced chemical deposition (PECVD) SiO₂ layer of 1 μm on top of Si wafer under various operating conditions. The c-axis-oriented ZnO film exhibit a sharp diffraction peak corresponding to the (0 0 2) reflection at 2θ=34.42. The fabrication process utilizing the micro-electro-mechanical systems (MEMS) technology of the SAW device is described. Simulation of the RF-SAW filter is performed. Measurements and experimental work are presented for the RF-SAW device.     

Tandem small molecule organic photovoltaic cells with broad spectral response up to 1 μm and a high open-circuit voltage

We report a series-connected small molecule tandem photovoltaic cell utilizing two donors with complementary photovoltaic characteristics, lead phthalocyanine (PbPc) in the front subcell and boron subphthalocyanine chloride (SubPc) in the back subcell, to achieve both near infrared (NIR) response up to 1 μm and high open-circuit voltage (V_OC) of more than 1.5 V in the same device. We find that the C₆₀ layer thickness in the front subcell has a critical impact on the overall optical structure and photovoltaic performance of the tandem device. By combining transfer matrix calculations with subcell-selective spectral measurements, we are able to tune the optical field distribution inside the active layers and increase the photocurrent outputs from both subcells, leading to EQE > 30% over the wavelength range 400 nm < λ < 900 nm. This optimized tandem cell exhibits J_SC = (5.5 ± 0.1) mA/cm², fill factor = 0.54, V_OC = 1.53 V, and a power conversion efficiency of (4.5 ± 0.2)%.     

A technique for truly linear LC VCO tuning, a proof of concept

Based on the understanding of the relation between the shape of the LC VCO tuning curve and the varactor characteristics, a technique using an array of unequal varactors with different bias was found to obtain a truly linear tuning curve. An LC VCO was designed using TSMC 0.13 μm 1.2 V/3.3 V IO process, the VCO frequency varies from 1.9 to 2.7 ghz as its control voltage varies from 0 to 1.2 V. The tuning gain was K_VCO=630 MHz/V ±9.5%.     

LP-MOCVD growth of ternary BxGa1−xAs epilayers on (0 0 1)GaAs substrates using TEB, TMGa and AsH3

Zinc-blende B_xGa_1−xAs alloys have been successfully grown on exactly oriented (0 0 1)GaAs substrates using triethylboron, trimethylgallium and arsine sources. The growth has been accomplished in a vertical low-pressure metalorganic chemical vapor deposition (LP-MOCVD) reactor. Boron incorporation behaviors have been extensively studied as a function of growth temperature and gas-phase boron mole fraction. The evolution of surface morphology was also observed.The maximum boron composition of 5.8% is obtained at the optimum growth temperature of 580 °C. RMS roughness over the surface area of 1×1 μm² is only 0.17 nm at such growth conditions. Based on the experimental results, it has been clearly shown that boron incorporation will decrease significantly at higher temperature (>610 °C) or at much lower temperature (?550 °C).     

Participatory or deliberative democracy? Exploring the mediation effects of perceived online deliberation and online interactive activities on social outcomes

Using the structural equation modeling method (N = 811), this study explores the structural relationships among online news consumption, political participation and social trust, with a focus on the mediating effects of online users’ deliberative perceptions and news-related online interactive activities. The analysis confirms that users’ perceptions of online deliberation exert a significant mediating effect on users’ levels of news consumption, political participation, and social trust. Users’ interactive civic messaging behaviors, on the other hand, solely enhance participatory intentions. The findings also show that the consumption of political news and the consumption of entertainment news have different effects on users’ perceptions of online deliberation, social trust, and political participation. Specifically, while political news has a direct and relatively strong influence on participation, entertainment news has a limited and indirect effect on participation. Online interactive activities are negatively associated with users’ perceived competency for online deliberation. Further implications of the study are also discussed.