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Lateral $\beta $ -Ga2O3 MOSFET for power switching applications with a 1.8 kV breakdown voltage and a record power figure of merit of 155 MW/cm2 are demonstrated. Sub- $\mu \text{m}$ gate length combined with gate recess was used to achieve low ON-state resistances with reasonable threshold voltages above −24 V. The combination of compensation-doped high-quality crystals, implantation-based inter-device isolation, and SiN x -passivation yielded in consistently high average breakdown field strengths of 1.8–2.2 MV/cm for gate–drain spacings between 2 and 10 $\mu \text{m}$ . These values outperform the results of more established wide-bandgap device technologies, such as SiC or GaN, and the major Ga2O3 material promise—a higher breakdown strength—is well demonstrated.

We report the first demonstration of self-aligned gate (SAG) β-Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs) as a path toward eliminating source access resistance for low-loss power applications. The SAG process is implemented with a subtractively defined and etched refractory metal, such as Tungsten, combined with ion-implantation. We report experimental and modeled DC performance of a representative SAG device that achieved a maximum transconductance of 35 mS mm−1 and an on-resistance of ∼30 Ω mm with a 2.5 μm gate length. These results highlight the advantage of implant technology for SAG β-Ga2O3 MOSFETs enabling future power switching and RF devices with low parasitic resistance.

In this paper we present a concept on the defect generation and annihilation during the homoepitaxial growth step of cubic silicon carbide by sublimation epitaxy on templates grown by chemical vapor deposition on silicon substrates. Several structural defects like stacking faults, twins and star defects show opposite evolution from the template layer into the sublimation grown material. While single planar defects tend to annihilate with increasing layer thickness, the defect clusters assigned to the star defects are enlarging. These issues contribute to a balance of how to achieve the best possible quality on thick layers.

In this work a new approach for the production of freestanding cubic silicon carbide (3C SiC) in (001) orientation is presented which is based on the combination of chemical vapor deposition (CVD) and the fast sublimation growth process (FSGP). Fast homoepitaxial growth of 3C SiC using sublimation epitaxy on a template created by CVD growth on silicon substrates allows to obtain thick freestanding material with low defect densities. Using standard silicon wafers as substrate material permits a cost efficient process and the applying of wafers with different orientations. The (001) orientation used in this work will potentially allow further heteroepitaxial growth of other cubic semiconductors, like e.g. gallium nitride (GaN).

In this work ion-implanted p+/n diodes have been used as minimum ionizing particle (MIP) detectors. The diode structure is based on a 0.45 $m deep, NA = 4×1019 cm-3 doped p+ anode, ion implanted in an n-type epilayer with thickness equal to 55 $m and nominal donor doping ND = 2×1014 cm-3. The diode breakdown voltages were above 1000V. At 1000V reverse bias the diode leakage current was of the order of 1 nA. The punch through depletion voltage was nearing the range 220-250 V. The charge collection efficiency to minimum ionizing particle was investigated by a 90Sr β source. The pulse height spectrum was measured as a function of the reverse voltage in the range 0-605 V. At each bias point the signal was stable and reproducible, showing the absence of polarization effects. At 220 V the collected charge was 2970 e- and saturated at 3150 e- near 350 V. At the moment, this is the highest collected charge for SiC detectors. At bias voltages over 100V the spectrum was found to consist of two peaks clearly separated. Around 250 V the signal saturates, in agreement with CV results.

Die numerische Stromungssimulation (Computational Fluid Dynamics: CFD) etabliert sich zunehmend als Werkzeug zur Analyse und Auslegung in der chemischen Industrie. Aus Sicht der CFD-Anwender der chemischen Grosindustrie werden exemplarisch CFD-Projekte aus verschiedenen Bereichen vorgestellt. Diese Bereiche sind einer Prozesskette nachempfunden: Transportieren, Mischen, Reagieren und Trennen von Stoffen. Es werden aus verfahrenstechnischer Sicht die wichtigsten Stufen und Entscheidungen bei dem Einsatz dieses Werkzeuges geschildert. Der Beitrag mochte Verstandnis fur die Moglichkeiten und Chancen, aber auch die Grenzen der numerischen Stromungssimulation vermitteln. CFD in Chemical Process Engineering from an Industrial Perspective Computational fluid dynamics (CFD) is increasingly becoming established as a tool for analysis and design in the chemical industry. Several projects from various areas are introduced as examples of CFD projects from the perspective of the CFD user in chemical industry. The areas chosen are based on those in a process chain: transportation, mixing, reaction, and separation of materials. The most important steps and decisions in the use of CFD are presented from the perspective of the process engineer. This paper attempts to convey an appreciation for the possibilities and opportunities, but also for the limits of computational fluid dynamics.

Basic Research on Ultrasonic Production of Oil-in-Water-Emulsions This article presents basic research results for production of oil in water emulsions under ultrasonic irradiation. A new theoretical model supports experimental work. Special attention is given to the transfer of batch experiments to continuous emulsification processes. Our experimental findings prove that final drop size essentially depends on specific power density. Drop size decreases with increasing residence time in the ultrasonic field until a system specific, minimum drop size is obtained. Ultrasonic irradiation leads to turbulent flow conditions on a macroscopic and a microscopic scale. Our model based on the theory of turbulent drop break up predicts drop size and can be used to design equipment for ultrasonic emulsification.

Sn-doped gallium oxide (Ga2O3) wrap-gate fin-array field-effect transistors (finFETs) were formed by top-down BCl3 plasma etching on a native semi-insulating Mg-doped (100) β-Ga2O3 substrate. The fin channels have a triangular cross-section and are approximately 300 nm wide and 200 nm tall. FinFETs, with 20 nm Al2O3 gate dielectric and ∼2 μm wrap-gate, demonstrate normally-off operation with a threshold voltage between 0 and +1 V during high-voltage operation. The ION/IOFF ratio is greater than 105 and is mainly limited by high on-resistance that can be significantly improved. At VG = 0, a finFET with 21 μm gate-drain spacing achieved a three-terminal breakdown voltage exceeding 600 V without a field-plate.

Cubic silicon carbide is a promising material for medium power electronics operating at high frequencies and for the subsequent growth of gallium nitride for more efficient light emitting diodes. We present a new approach to produce freestanding cubic silicon carbide (3C-SiC) with the ability to obtain good crystalline quality regarding increased domain size and reduced defect density. This would pave the way to achieve substrates of 3C-SiC so that the applications of cubic silicon carbide material having selectively (111) or (001) oriented surfaces can be explored. Our method is based on the combination of the chemical vapor deposition method and the fast sublimation growth process. Thin layers of cubic silicon carbide grown heteroepitaxially on silicon substrates are for the first time used for a subsequent sublimation growth step to increase layer thicknesses. We have been able to realize growth of freestanding (001) oriented 3C-SiC substrates using growth rates around 120 μm/h and diameters of more than 10 mm. The structural quality from XRD rocking curve measurements of (001) oriented layers shows good FWHM values down to 78 arcsec measured over an area of 1 × 2 mm2, which is a quality improvement of 2–3 times compared with other methods like CVD. Funding agencies|Angpanneforeningen Research Foundation||Swedish Energy Agency||Bundesministerium fur Bildung und Forschung (BMBF)| 03SF0393

In this work we analyzed the radiation hardness of SiC p/sup +//n diodes used as minimum ionizing particle (MIP) detectors after very high 1 MeV neutron fluences. The diode structure is based on ion implanted p/sup +/ emitter in an n-type epilayer with thickness equal to 55 /spl mu/m and donor doping N/sub D/ = 2/spl times/10/sup 14/ cm/sup -3/. The diode breakdown voltages were above 1000 V. At 1000 V the leakage currents are of the order of 1 nA for all the measured diodes. The full depletion voltage is near 220-250 V. The charge collection efficiency to minimum ionising particle has been investigated by a /sup 90/Sr /spl beta/ source. At 250 V the collected charge of the unirradiated diodes saturates near 3000 e/sup -/. At bias voltages over than 100 V the energy spectrum of the collected charge was found to consist of two peaks clearly separated. At around 250 V the signal saturates, in agreement with CV results. These devices have been irradiated considering 6 different fluences, logarithmically distributed in the range 10/sup 14/-10/sup 16/ 1 MeV neutrons/cm/sup 2/. The leakage current after irradiation decreases. The collected charges decrease for increasing fluences, remaining very high only until some 10/sup 14/ n/cm/sup 2/.

In this work we analyzed the radiation hardness of SiC p/sup +/ n diodes used as minimum ionizing particle (MIP) detectors after very high 1 MeV neutron fluences. The diode structure is based on ion implanted p/sup +/ emitter in an n-type epilayer with thickness equal to 55 /spl mu/m and donor doping N/sub D/=2/spl times/ 10/sup 14/cm/sup -3/. The diode breakdown voltages were above 1000 V. At 1000 V the leakage currents are of the order of 1 nA for all the measured diodes. The full depletion voltage is near 220-250 V. The charge collection efficiency to minimum ionizing particle has been investigated by a /sup 90/Sr /spl beta/ source. At 250 V the collected charge of the unirradiated diodes saturates near 3000 e/sup -/. At bias voltages over 100 V the energy spectrum of the collected charge was found to consist of a signal peak well separated from the noise. At around 250 V the signal saturates, in agreement with CV results. These devices have been irradiated at 6 different fluences, logarithmically distributed in the range 10/sup 14/-10/sup 16/ (1 MeV) neutrons/cm/sup 2/. The leakage current after irradiation decreases. The collected charges decrease for increasing fluences, remaining very high only until some 10/sup 14/ n/cm/sup 2/.

The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 1035 cm-2 s-1 will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10 ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration ''Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders'' is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi- 3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented.

P type silicon layers for photovoltaic applications have been deposited on low cost multicrystalline silicon substrates prepared by directional solidification or by electromagnetic casting with solar grade charges. The thickness is between 4 to 20 μm. The layers were characterized by Light Beam Induced Current (LBIC) mappings at different wavelengthes. Collecting structures are p-n junctions or Al-Si semitransparent diodes. The layer and the substrate can be investigated separately by changing the wavelength of the LBIC maps, or/and by realizing a collecting structure on the free surface of the substrate.It is found that the same extended crystallographic defects are detected by LBIC in the layer and in the substrate. However their recombination strength in the layer is less marked probably due to a higher purity of the layer. The computed values of minority carrier diffusion length are close or larger than the film thickness and the investigated layers could be used to make solar cells.

We investigate the crystalline and electrical quality of thin layers epitaxially grown on polycrystalline substrates from metallic solution by the method of electron beam induced current, transmission electron microscopy and etching experiments. We observe a reduced recombination strength of dislocations and small angle grain boundaries, i.e. an improved electrical quality of the epitaxial layer compared to the substrate. The improved quality can be attributed (i) to an altered structure of grain boundaries and dislocations and (ii) to a reduced defect density in the epitaxial layer.