Foreword

This work reports on the performances of ohmic contacts fabricated on highly p-type doped 4H-SiC epitaxial layer selectively grown by vapor-liquid-solid transport. Due to the very high doping level obtained, the contacts have an ohmic behavior even without any annealing process. Upon variation of annealing temperatures, it was shown that both 500 and 800 °C annealing temperature lead to a minimum value of the Specific Contact Resistance (SCR) down to 1.3×10−6 Ω⋅cm2. However, a large variation of the minimum SCR values has been observed (up to 4×10−4 Ω⋅cm2). Possible sources of this fluctuation have been also discussed in this paper

A retrosynthetic biology approach to therapeutics: from conception to delivery

International audienceDe novo biosynthetic pathways are designed, assembled and optimized to produce high-value compounds such as drugs and chemical building blocks from renewable resources. Microorganisms are used as synthetic platforms of systems biology where biochemical pathways are engineered into the host metabolic network. Retrosynthetic biology offers a creative pathway design concept that has gained interest because of its potential to identify novel metabolic ways for therapeutic production. Retrosynthetic biology uses the backward search of retrosynthetic analysis to devise and optimize tailor-made pathways. The retrosynthetic process can be seamlessly integrated into a complete circuitry system for therapeutic applications where production, sensing and delivery act as constitutive interconnecting parts. The aim of this review is to highlight recent efforts toward synthetic design for therapeutic development

High-Voltage SiC-JFET Fabrication and Full Characterization

International audienceThis paper reports the design, the processing, the static characterisation, the switching behaviour and the high current stress test of 10 kV aimed 4H-SiC bipolar diodes. The actual breakdown voltage of the selected devices is between 7 kV and 8 kV. The switching characterisations show a good behaviour with a t rr of only 90 ns. No degradation was observed after the application of 10 000 high current pulses during the stress tests

High-Voltage SiC-JFET Fabrication and Full Characterization

International audienceThis paper reports the design, the processing, the static characterisation, the switching behaviour and the high current stress test of 10 kV aimed 4H-SiC bipolar diodes. The actual breakdown voltage of the selected devices is between 7 kV and 8 kV. The switching characterisations show a good behaviour with a t rr of only 90 ns. No degradation was observed after the application of 10 000 high current pulses during the stress tests

Very low specific contact resistance measurements made on a highly p-type doped 4H-SiC layer selectively grown by vapor-liquid-solid transport

This work reports on the performances of ohmic contacts fabricated on highly p-type doped 4H-SiC epitaxial layer selectively grown by vapor-liquid-solid transport. Due to the very high doping level obtained, the contacts have an ohmic behavior even without any annealing process. Upon variation of annealing temperatures, it was shown that both 500 and 800 °C annealing temperature lead to a minimum value of the Specific Contact Resistance (SCR) down to 1.3×10−6 Ω⋅cm2. However, a large variation of the minimum SCR values has been observed (up to 4×10−4 Ω⋅cm2). Possible sources of this fluctuation have been also discussed in this paper

Selective growth of p-doped SiC on diamond substrate by vapor–liquid–solid mechanism from Al–Si liquid phase

International audienceThis works deals with the localized growth of SiC on monocrystalline (100) diamond surface. It describes an attempt of selective epitaxy using vapor–liquid–solid (VLS) transport. Patterns of Al–Si stacking were melted and fed by propane. Morphology, structure and doping type of the SiC deposit were evaluated. The deposit was found to be successfully selective but polycrystalline, with the 3C-SiC polytype. Study of the initial step of growth showed that SiC nucleation occurs without any propane addition but just through the interaction of liquid Al–Si and diamond via a dissolution/precipitation process. The VLS transport mainly assists the growth of these nuclei by providing a secondary carbon source. This explains the random nucleation and the polycrystalline growth. Despite this, the deposit was dense enough to perform some preliminary electrical measurements which show encouraging results

Influence of process parameters on electrical properties of PiN diodes fabricated with a highly p-type doped layer selectively grown by VLS transport

International audienceSiC Selective Epitaxial Growth (SEG) by Vapor-Liquid-Solid (VLS) transport on a bowl-shaped geometry appears to be a promising solution to perform deep, highly doped and high quality p-type doped area. Such SEG-VLS growth of highly p-doped (> 5x1019 cm-3) SiC layer was successfully demonstrated recently on large and small areas fabricated by Reactive Ion Etching (RIE). Moreover, a high quality P++(VLS)-N junction can be achieved by using this technique that offer new prospects for the achievement of new power electronics devices, including deeply buried peripheral protection zones such as guard-rings or JBS structures

Towards the fabrication and measurement of high sensitivity SiC-UV detectors with oxide ramp termination

International audienceThe paper is focused on the fabrication and measurement of the high UV detection performances 6H-SiC pn photodiodes with an efficient planar termination. The oxide ramp technology used for these photodetectors is extensively presented.. Two oxide layers with a total thickness of 1µm, were grown onto the epilayer. In order to obtain an oxide ramp profile, a suitable etching process was used. Experimental measurements indicate that a ramp angle of less than 4° was achieved. The p + layer was obtained by Al implantation. Ni and Pt were deposited on the back side and on the p layer, respectively. The OBIC technique was used for optical measurements of the samples. The diode's surface was scanned left to right and up to down by a 4 µm laser spot modulated at 70 Hz by a chopper. A computer controls the movement of the test device, and registers the current measurement as a function of the position of the UV spot. The impact of diode's bias as well as their photoresponse on some incident light power values has been revealed by extensive measurements and numerical simulations. The measurement show a stronger diode's bias effect on its optical properties than the simulation data. We propose this paper for poster presentation at C2 Optical devices and system

A comparative study of high temperature Aluminium post-implantation annealing in 6H and 4H-SiC, non-uniformity temperature effects

International audience4H- and 6H-SiC small samples were implanted by keV Al+ ions at room temperature and annealed in an induction heating furnace, at the center of the susceptor, for different temperatures and times in the range 1600-1800°C and 5-60 min, respectively. The implanted layers were amorphous but the SiC crystalline structures were recovered after annealing, as measured by Rutherford Back-Scattering analyses in Channeling geometry.Al+ electrical activation determined by sheet resistance and Hall effect measurements increases with the annealing temperature or time, on both polytypes. When whole SiC wafers were annealed in the same induction heating furnace, sheet resistance mapping systematically presented a radial gradient from the center to the periphery of the wafer. The measured linear dependence between sheet resistance and temperature allowed us to rebuild the radial temperature gradient at the crucible-susceptor furnace during the annealing process