Papers by Keyword: N2O

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Authors: Ming Jin Wang, Hong Wang, Cui Qing Li, Fu Chen Ding, Yong Ji Song, Ka Sha Cai
Abstract: Nitrous oxide (N2O) is a kind of important greenhouse gas,which has the potential damage on the ozone layer and people’s physical health. A series of RPSA loading metals catalysts were prepared by impregnation. The catalysts were characterized by XRD, TG-MS, NH3-TPD, SEM method. The catalytic performance for N2O decomposition was evaluated. Cu-based catalyst is the best activity for N2O decomposition, T95 is 540°C.
666
Authors: Aurore Constant, Philippe Godignon
Abstract: Gate oxides for SiC lateral MOSFETs have been formed in N2O by rapid thermal processing (RTP) as an alternative to the conventional furnace process. This innovative oxidation method has not only the advantage to significantly reduce the thermal budget compared to a standard oxidation, but also to produce oxide layers with quality comparable to the one grown in a conventional furnace. Moreover, a significant improvement of the oxide quality and MOSFET performance is observed when performing in-situ a H2 anneal prior to oxidation as surface pretreatment. The channel mobility and the breakdown field of the gate oxide are considerably increased.
221
Authors: Christian Strenger, Anton J. Bauer, Heiner Ryssel
Abstract: Metal-oxide-semiconductor (MOS) capacitors were formed on 4H-silicon carbide (SiC) using thermally grown silicon dioxide (SiO2) as gate dielectrics, both with and without nitrogen incorporation within the oxide. The field dependence of the charge trapping properties of these structures was analyzed and linked to the observed Fowler-Nordheim current degradation. Furthermore, first considerations were presented that indicate an electron impact emission induced generation of positive oxide trapped charge.
382
Authors: Shuji Katakami, Manabu Arai, Kensuke Takenaka, Yoshiyuki Yonezawa, Hitoshi Ishimori, Mitsuo Okamoto, Kazutoshi Kojima, Kenji Fukuda
Abstract: We investigated the effect of post-oxidation annealing in wet O2 and N2O ambient, following dry O2 oxidation on the SiC MOS interfacial properties by using p-type MOS capacitors. The interfacial properties were dramatically improved by the introduction of hydrogen or nitrogen atoms into the SiO2/SiC interface, in each POA process. Notably, the N2O-POA process at 1200 °C or higher reduced the interface state density more effectively than the wet-O2-POA process, and offers a promising method to further improve the inversion channel mobility of p-channel SiC MOS devices.
709
Authors: Lukas K. Swanson, Patrick Fiorenza, Filippo Giannazzo, Fabrizio Roccaforte
Abstract: This work reports on the morphological, structural and electrical effects of a nitrous oxide (N2O) ambient post-oxidation annealing (POA) of the SiO2/4H-SiC interface. In particular, a conventional electrical characterization of MOS capacitors showed that nitrous oxide POA reduces the presence of both fixed oxide charge and the density of interface states. A local atomically flat interface was observed by transmission electron microscopy with only a moderate step bunching observed at a macroscopic scale. A novel nanoscale characterization approach via scanning spreading resistance microscopy resolved local electrical changes induced at the SiC surface exposed to N2O POA. This result subsequently revealed additional insight into the mechanism for the improved device performance subjected to N2O POA treatment.
719
Authors: Lukas K. Swanson, Patrick Fiorenza, Filippo Giannazzo, S. Alessandrino, S. Lorenti, Fabrizio Roccaforte
Abstract: This work reports on the morphological, structural and electrical effects of a nitrous oxide (N2O) ambient post-oxidation annealing (POA) of the SiO2/4H-SiC interface. In particular, a conventional electrical characterization of MOS capacitors showed that nitrous oxide POA reduces the presence of both fixed oxide charge and the density of interface states. A local atomically flat interface was observed by transmission electron microscopy with only a moderate step bunching observed at a macroscopic scale. A novel nanoscale characterization approach via scanning spreading resistance microscopy resolved local electrical changes induced at the SiC surface exposed to N2O POA. This result subsequently revealed additional insight into the mechanism for the improved device performance subjected to N2O POA treatment.
715
Authors: Ryouji Kosugi, Kenji Fukuda, Kazuo Arai
Abstract: A high temperature rapid thermal processing (HT-RTP) above 1400oC was investigated for use in the gate oxide formation of 4H-SiC by a cold-wall oxidation furnace. The gate oxide film of ~50nm can be formed for several minutes in the oxidizing atmospheres such as N2O and O2, where the oxidation rates were 8-10nm/min. After the initial oxide formation, the HT-RTPs in various ambient gases were conducted, and the dependences of their MOS interface properties on the gases were evaluated by a capacitance-voltage (CV) measurement. Based on the results, the process sequence of gate oxidation was determined as follows; the initial oxide was formed by the HT-RTO (oxidation) in N2O or in O2 with subsequent post annealing in Ar ambient, and then the HT-RTN (nitridation) in NO was conducted. The total process time becomes 20-50min. The interface trap density (Dit) of fabricated MOS capacitor shows 3-5x1011cm-2eV-1 at Ec-E~0.2eV. The field-effect channel mobility of fabricated 4H-SiC lateral MOSFETs was ~30cm2/Vs.
669
Authors: Hong Yu Zhang, Guo Xue Li, Hong Fei Wei
Abstract: Because of high moisture content and compact structure, composting kitchen waste would discharge by-products such as leachate, ammonia (NH3), and greenhouse gases, and these can cause secondary environmental pollution. In this study, continuous measurements of gas emissions were carried out and detailed gas emission patterns were obtained using forced aeration system at aerations of 2·10-4 (T1), 4·10-4 (A2) and 6·10-4 ( (A3) m3·kgDM-1·min-1. During the experiment, temperature and oxygen content were determined, and continuous measurements of NH3 and gaseous emissions (CH4, N2O, and NH3) were taken. The results indicated that the aeration had a significant effect on NH3, CH4 and N2O emission (p<0.05). The highest concentration of NH3, CH4 and N2O were all observed in the treatment of T2. The productions of NH3 were reduced by 59.6% and 33.7%, and greenhouse gases (GHG) were reduced by 50.8% and 40.5% for T1 and T2 that compared to T3, respectively. Obviously, the aeration has great influence on NH3 and GHG emissions. In this study, the aeration was 2·10-4 m3·kgDM-1·min-1 in favor of NH3 and GHG reduction.
1904
Authors: Antonella Poggi, Francesco Moscatelli, Andrea Scorzoni, Giovanni Marino, Roberta Nipoti, Michele Sanmartin
Abstract: Many investigations have been conducted on the growth conditions of SiO2 on SiC to improve the oxide quality and the properties of the silicon carbide-silicon dioxide interface. In this work a comparison between a wet oxidation and an oxidation in N2O ambient diluted in N2 is proposed. The interface state density Dit near the conduction-band edge of SiC has been evaluated by conventional C-V measurements obtaining results similar or better than the literature data. Furthermore, the slow trapping phenomena have been studied and preliminary results are reported.
979
Authors: Min Wang, Jie Chen, Niu Liu, Ya Wang
Abstract: Mid-infrared lasers are very suitable for high-sensitive trace-gases detection for their wavelengths cover the fundamental absorption lines of most gases. Quantum-cascade (QC) lasers have been demonstrated to be ideal light sources with its special power, tuning and capability of operating in room-temperature. All these merits make it appropriate for the high resolution spectrum analysis. The absorption spectrum monitoring technology based on the QC laser pulsed operating in the room temperature, combining with the strong absorption of the gas molecule in the basic frequency, has become an effective way to monitor the trace gas with the characteristic of high sensitivity, good selectivity and fast response. In this paper, the inter-pulse spectroscopy based on a room-temperature distributed-feedback pulsed QC laser was introduced. Our approach to trace gas monitoring with QC lasers relies on short current pulses which are designed to produce even shorter light pulses. Each pulse corresponds to a single point in a spectrum. The N2O absorption spectrum centered at 2178.2cm-1 was also obtained.
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