1,721,124 research outputs found
Editorial for the Special Issue on Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume II
Full text linkWide bandgap (WBG) semiconductors are becoming a key enabling technology for several strategic fields of human activities [...
On the electro-optical characteristics of CMOS compatible photodiodes
No full textA numerical model for the solution of semiconductor-device equations in the presence of an optical-generation effect is presented. This model, developed as a part of the general-purpose semiconductor-device analysis program HFIELDS, is to be applied to the analysis of optical sensors used in semiconductor integrated imagers. Preliminary theoretical results on CMOS-compatible photodiodes are presented and compared with experiments
Effects of mole fraction variations and scaling on total variability in InGaAs MOSFETs
Full text linkVariability is one of the major roadblocks for III-V semiconductors in nanoscale devices, according to the recent International Roadmap for Devices and Systems (IRDS). A particular concern is the detrimental effect of variability of threshold voltage due to channel compositional variations. In this paper, we investigate the impact of this variability source and the effects of scaling on the performance of Dual-Gate-Ultra-Thin-Body (DG-UTB) In0.53Ga0.47As MOSFETs. We model mole fraction variations in terms of the Indium content by taking into account the spatial inhomogeneity of the channel and the corresponding bandgap variations, analyzing the effects on threshold voltage variability. We thus define a variability source, i.e., Band Gap Fluctuation (BGF), and we compare the associated variability with the ones from other important sources, namely, Random Dopant Fluctuation (RDF), Work Function Fluctuation (WFF), Body- and Gate-Line Edge Roughness (B-LER and G-LER). We then define three corner cases for mole fraction variations to determine worst-case variability. Finally, the impact of scaling on variability is assessed by comparing results for two technology nodes on the linear and saturation threshold voltage, V-T,V-lin,V- V-T,V-sat, on-current, I-ON, leakage current, I-OFF, and linear and saturation sub-threshold slope, SS. We find that although scaling has no impact on BGF-induced V-T variability, it increases the total V-T, lin variability as well as that for I-ON and I-OFF
Investigation of high-electric-field degradation effects in AlGaN/GaN HEMTs
No full textHigh-electric-field degradation phenomena are
investigated in GaN-capped AlGaN/GaN HEMTs by comparing
experimental data with numerical device simulations. Under
power- and OFF-state conditions, 150-h DC stresses were carried
out. Degradation effects characterizing both stress experiments
were as follows: a drop in the dc drain current, the amplification of
gate-lag effects, and a decrease in the reverse gate leakage current.
Numerical simulations indicate that the simultaneous generation
of surface (and/or barrier) and buffer traps can account for
all of the aforementioned degradation modes. Experiments
also showed that the power-state stress induced a drop in the
transconductance at high gate–source voltages only, whereas
the OFF-state stress led to a uniform transconductance drop
over the entire gate–source-voltage range. This behavior can be
reproduced by simulations provided that, under the power-state
stress, traps are assumed to accumulate over a wide region
extending laterally from the gate edge toward the drain contact,
whereas, under the OFF-state stress, trap generation is supposed
to take place in a narrower portion of the drain-access region
close to the gate edge and to be accompanied by a significant
degradation of the channel transport parameters
Surface effects on turn-off characteristics of AlGaAs/GaAs HFETs
No full textThe gate-lag turn-off transient of as-fabricated and hut-carrier stressed power AlGaAs/GaAs NFETs is addressed by quantitatively comparing experimental data with device simulations accounting for the occupation dynamics of surface deep-acceptor trays. Gate-lag waveforms of increasingly degraded devices can be accurately simulated by suitably increasing the surface trap density
Current collapse and high-electric-field reliability of unpassivated GaN/AlGaN/GaN HEMTs
No full textLong-term ON-state and OFF-state high-electric-field
stress results are presented for unpassivated GaN/AlGaN/GaN
high-electron-mobility transistors on SiC substrates. Because of
the thin GaN cap layer, devices show minimal current-collapse
effects prior to high-electric-field stress, despite the fact that
they are not passivated. This comes at the price of a relatively
high gate-leakage current. Under the assumption that donor-like
electron traps are present within the GaN cap, two-dimensional
numerical device simulations provide an explanation for the influence
of the GaN cap layer on current collapse and for the
correlation between the latter and the gate-leakage current. Both
ON-state and OFF-state stresses produce simultaneous currentcollapse
increase and gate-leakage-current decrease, which can be
interpreted to be the result of gate–drain surface degradation and
reduced gate electron injection. This study shows that although
the thin GaN cap layer is effective in suppressing surface-related
dispersion effects in virgin devices, it does not, per se, protect the
device from high-electric-field degradation, and it should, to this
aim, be adopted in conjunction with other technological solutions
like surface passivation, prepassivation surface treatments, and/or
field-plate gate
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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