1,721,089 research outputs found
Simulation of the effect of grain-boundaries in backside-passivated CIGS solar cells
Full text linkWe carry out numerical 3D simulations of CIGS cells with back-side Al2O3 passivation and point contact openings in the presence of grain boundaries in the absorber. We consider CIGS cells with different absorber thickness, from 0.35 to 3 mu mathrm{m}. For thinner absorbers (1 mu mathrm{m} or less) we observe that GBs terminating on the Al2O3 are completely or almost completely passivated, while the effectiveness of the passivation decreases for thicker absorbers. GBs terminating on the point contact, instead, significantly lower the efficiency, regardless of absorber thickness. The presence of grain boundaries and the dimension of grains should therefore be taken into consideration when optimizing the back-side point contact array geometry
On the effect of deep defects on the Voc deficit in high-GGI CIGS absorbers: A numerical study
No full textUsing numerical simulations, we investigate the effect of a deep donor known to exist at EV + 1.33 eV, as a contribution to explain the large VOC deficit of Ga-rich absorbers.. We find that uniform GGI absorbers with GGI > 0.5 suffer for the presence of this deep donor, with the VOC deficit linearly increasing with GGI. On the other hand, simulations indicate that this deep donor is unlikely to be a significant performance limiter in double-graded cells
An improved procedure to test CMOS ICs for Latch-up
No full textAn improved, more complete strategy for latch-up testing of CMOS ICs is proposed in order to take into account important effects that have been neglected by standard procedures, but which are shown to reduce considerably the circuit resistance to latch-up. These phenomena include interactions among carriers injected by different p-n-p-n structures, voltage drops on power supply and ground lines caused by output pin load currents, and effects of power supply voltage and chip heating. All experiments with regard to this work have been performed by means of automatic test equipment, which provides the possibility of completely controlling the circuit state and operating conditions during testin
Extraction of the Series Resistances and Effective Channel Length of GaAs MESFETs by means of Electrical Methods
No full textThe authors present a numerical study on electrical methods to measure the source and drain resistances and the effective channel length of state-of-the-art gallium arsenide MESFETs. In particular, the effects of scaling on the physical meaning and gate voltage dependence of the extracted values are investigated. Fringing effects at the gate edges are found to be responsible for a substantial bias dependence of the series resistances, and hence for possible inaccuracies of extraction procedures that overlook such phenomena. A novel extraction technique is also proposed to overcome in part the limitations of conventional approaches
Effects of the interaction of neighboring structures on the Latch-up behavior of C-MOS ICs
No full textAn experimental investigation on the interaction between different parasitic devices in CMOS ICs from the point of view of latchup triggering is outlined. The study, carried out by means of ad hoc test structures, shows that this interaction: (a) can lead to significant increase in latchup susceptibility; (b) can involve devices very distant from one another; and (c) is not always suppressed by guard ring protections. The main features of the experimental results are discussed and explaine
1-D numerical model applied to flood routing in presence of large flooded areas connected to the river. The case study of Senio
No full textIn-circuit Shoot-through-based Characterization of SiC MOSFET TSEP Curves for Junction Temperature Estimation
No full textJunction temperature estimation for power electronics devices is gaining more importance every day. It enables predictive maintenance and full exploitation of the power handling capability of both traditional and wide band-gap devices. The on-state voltage is known to be a good Temperature-Sensitive Electrical Parameter (TSEP), especially for MOSFETs. The main issue in its use is the need to characterize the voltage-temperature-current relationship on a per-device basis (calibration) in a controlled environment, which increases the cost for the final application.This paper presents a novel automatic calibration procedure. It builds on the innovative controlled shoot-through technique, introduced by the authors. This allows to precisely control the self-heating power of the switch and let the current flow through the device in a controlled way, even in the absence of load, provided that a half-bridge circuit is used. A specific algorithm is presented to build the voltage-temperature characteristic curve directly in-circuit and without any load connected at the bridge output. This novel technique is compared to the traditional one, relying on device characterization in a thermal chamber
Investigation on the Thermal Stability of Silicon-carbide MOSFETs operating in Controlled Shoot-through mode
No full textThe Controlled Shoot-Through technique is an emerging and promising one for thermal control and monitoring of power MOSFETs. In this work we investigate the thermal stability of the power device in current-controlled mode at low gate voltages, to identify the effects of long pulses, as needed by in-circuit thermal analysis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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