The effect of hydrogen and oxygen surface termination atoms on the visible luminescence of porous Si was investigated for underlying physical mechanism. Atmospheric thermal treatment up to 1000 °C was carried out to study the functional relationship between the surface coverage and photoluminescence (PL). The results show that oxygen incorporation induces surface modification that enhance the PL efficiency after the removal of all SiHx (x=1–3) species. The presence of oxygen atoms can also account for the observed PL redshift along with the usual blueshift. The molecular orbital calculations on the cluster modeling showed the significance of oxygen atoms in modifying the electronic structure of porous Si.

A new design and processing concepts have been applied to develop practical SiC trench MOSFETs for high power applications. The designed trench MOSFET has a MOS structure consisting of epitaxially grown n‐type SiC trench sidewall layers. The current flows via an accumulation mode through the channel defined in the epitaxially grown SiC sidewall layer. The channel is depleted by the built‐in fields of the p‐type SiC base layer and the p‐poly‐Si gate, that control the channel conditions. The simulation based investigations revealed that the formed channel can withstand up to the avalanche breakdown condition. The structure of the n‐type SiC trench sidewall epi‐layer has been optimized to realize the blocking voltage of more than 1000 V for SiC MOSFETs with low on‐state resistance. Moreover, our designed structure can address most of the open issues related to the MOS interface, viz., high surface state density, low channel mobility and high electric field at the trench base of the MOS structure. We have fabricated the first 2 mm square large size 6H‐SiC trench MOSFET chip, in which 2380 hexagonal structural microcells of 23 μm pitch were integrated. The fabricated 6H‐SiC trench MOSFET on (0001‐) C‐face wafers feature the on‐state resistance as low as 23.84 m Ω cm2 with blocking voltage of more than 450 V.

Transfection of an immortalized cell line (AE), derived from Syrian hamster embryo cells, with human papillomavirus type 18 (HPV 18) DNA induced morphological transformation and these transformed cells were tumorigenic in nude mice. Southern blot analysis revealed that the transfected viral DNA was retained in all the cell lines tested, however, all these transformed cells contained only less than one copy per cell of viral genome. Eleven cloned cell lines were established from a tumor cell line obtained after explantation of a tumor into a nude mouse. Two lines revealed no viral sequences by both Southern blot hybridization and polymerase chain reaction, whereas the nine others contained the remaining viral sequences. These results are highly suggestive of a 'hit and run' oncogenesis by this virus.

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