Influence of inserting AlN between AlSiON and 4H-SiC interface for the MIS structure

A control of interface between gate insulating film and semiconductor is required to achieve high-power field effect transistors (FET) using SiC. To improve the interface between the high-k layer and SiC, we propose inserting an AlN layer as an interfacial layer. The reason for selecting AlN film is that it has a wide bandgap, as well as almost the same lattice constant as that of 4H-SiC. The insertion of AlN film between 4H-SiC and the insulating film effectively reduces the interfacial roughness. The roughness of the interface between AlN and SiC can be suppressed compared with that of the thermal oxidized SiC. Moreover, the AlSiON film was deposited on the AlN layer as a high dielectric gate insulating film with low leakage current at high temperature and low space charge. The C-V characteristics of the AlSiON/AlN/SiC MIS structure with an AlN buffer layer are improved by increasing the deposition temperature of the AlN film. This demonstrates that AlSiON/AlN/SiC is one of attractive MIS structures for SiC devices.     

Synthesis of multisubstituted 1H-pyrrole: selenium-catalyzed reaction of γ-nitro substituted carbonyl compounds and carbon monoxide

The novel and efficient selenium-catalyzed reductive N-heterocyclization of γ-nitro substituted carbonyl compounds with carbon monoxide has been developed. Various multisubstituted 1H-pyrroles can be easily prepared by this protocol. The one-pot synthesis of ethyl 1H-pyrrole-3-carboxylate derivatives was also successfully attained by the selenium-catalyzed reaction of β-ketoester, vinyl nitro compounds and carbon monoxide.     

A direct method for the decontamination of a fly ash amended wet soil,artificially polluted with dioxins

We report hereby the first method of direct treatment of a wet soil containing toxic polychloroderivatives. Using a system with metallic Ca and 5% Rh fixed on charcoal in methanol, soil samples artificially polluted with fly ash containing polychloro-dibenzodioxins (PCDDs), polychloro-dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (co-PCBs), and having 69.2% to 84.6% moisture content, were successfully treated and decontaminated. This treatment afforded excellent hydrodechlorination yields for the 29 most toxic congeners of PCDDs, PCDFs and PCBs (98.3% degradation yield based on toxic equivalent quotient — or TEQ) after a 24 h treatment, at room temperature.      

Parallel Fock matrix construction with distributed shared memory model for the FMO‐MO method

A parallel Fock matrix construction program for FMO‐MO method has been developed with the distributed shared memory model. To construct a large‐sized Fock matrix during FMO‐MO calculations, a distributed parallel algorithm was designed to make full use of local memory to reduce communication, and was implemented on the Global Array toolkit. A benchmark calculation for a small system indicates that the parallelization efficiency of the matrix construction portion is as high as 93% at 1,024 processors. A large FMO‐MO application on the epidermal growth factor receptor (EGFR) protein (17,246 atoms and 96,234 basis functions) was also carried out at the HF/6‐31G level of theory, with the frontier orbitals being extracted by a Sakurai‐Sugiura eigensolver. It takes 11.3 h for the FMO calculation, 49.1 h for the Fock matrix construction, and 10 min to extract 94 eigen‐components on a PC cluster system using 256 processors. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010