Elimination of the base layer in conventional hot electron transistor has possibility to minimize the scattering in the propagation. In previous study, we fabricated InP/InGaAs hot electron transistors without a doped layer in the propagation region by fabricating a 25-nm-wide emitter and Schottky gate electrodes located at both sides of an emitter mesa. However, there were some problems in fabricated device. To solve these observed problems, we proposed and fabricated a new structure with hot electrons propagating only in the intrinsic semiconductor. An insulated gate was introduced in hot electron transistors, in which hot electrons are propagated only in the intrinsic region after extraction from a heterostructure launcher. Clear collector current modulation by the insulated gate and a current density of 160 kA/cm 2 were confirmed.
It has become clear that the self-consistent Ornstein-Zernike approximation (SCOZA) is a microscopic liquid-state theory that is able to predict the location of the critical point and of the liquid-vapour coexistence line of a simple fluid with high accuracy. However, applications of the SCOZA to continuum systems have been restricted up to now to liquids where the interatomic potentials consist of a hard-core part with an attractive two-Yukawa-tail part. We present here a reformulation of the SCOZA that is based on the Wertheim-Baxter formalism for solving the mean-spherical approximation for a hard-core-multi-Yukawa-tail fluid. This SCOZA version offers more flexibility and opens access to systems where the interactions can be represented by a suitable linear combination of Yukawa tails. We demonstrate the power of this generalized SCOZA for a model system of fullerenes; furthermore, we study the critical behaviour of a system with an explicitly density-dependent interaction where the phenomenon of double criticality is observed. Finally, we extend our SCOZA version to the case of a binary symmetric mixture and present and discuss results for phase diagrams.
Moore's law has almost reached the limit of resolution on semiconductor die and, therefore, multidie packaging is one of the alternative solutions. Substrate materials currently use organic build-up films and silicon substrates [through silicon via (TSV)] in applications. But recently, organic films, too, have reached the resolution limit, and TSV is expensive. In this situation, nonalkali glass (glass) and fused silica (SiO2) substrates are expected to be good alternatives in high-frequency signal transfer applications like 5G telecommunication. But the via holes are hard to process with less defects (tips and cracks) on the glass and SiO2 substrates. Deep ultraviolet (DUV) excimer laser ablation is expected to have a finer (<10 μm) resolution with a shorter wavelength (248–193 nm) and also hard material processing with a higher photon energy (5–6.4 eV). Therefore, the authors have explored the application of the DUV excimer laser ablation process for a via hole on hard materials like glass and SiO2 substrates. In this study, they have investigated the via hole quality through the DUV excimer laser ablation process. The results show the possibilities of micromachining on both glass and SiO2 substrates. The authors have succeeded by achieving a value of <50 μm through the via hole grid aspect ratio of 6 on the glass substrate without any significant defects. As the ablation rate is quite an affordable value, DUV excimer lasers are expected to play a crucial role in the next-generation manufacturing process for semiconductor packages. The authors also investigate the SiO2 substrate with DUV excimer lasers.
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