The in situ, heteroepitaxial growth of Ge films grown on (100) n-GaAs, followed by in situ deposition of a Si3N4/Si insulator to form a Ge metal-insulator-semiconductor structure, is reported. The growth of the Ge, Si, and Si3N4 is carried out in an ultrahigh vacuum, chemical vapor deposition system which is vacuum connected to an adjacent III-V molecular beam epitaxy machine in which the GaAs is grown. The Ge is grown at low temperature (250 °C) using GeH4 and excited He from a remote plasma. After a rapid thermal annealing step, a marked reduction in hysteresis is observed in the capacitance-voltage characteristics and the density of interface trap states at the Si3N4/Si/Ge interface, as determined from the magnitude of the conductance peak, is found to decrease by a factor of 5, to 1×1011 eV−1 cm−2.
3 ) were studied in homometathesis of hex 1 ene, metathesis polycondensation of deca 1,9 diene, and ring opening metathesis polymerization of cy clooctene. The nature of the carbene fragment in the tungsten catalysts substantially affects their catalytic activity. Silicon containing catalysts 1 and 2 were found to be 3-5 times less active than their hydrocarbon analogs 3 and 4. Metathesis polymerization of cyclooctene in the bulk with initiators 1-4 completed within a few minutes to form a block. Stereoregularity of the formed polyoctenamers depends to a considerable extent on the nature of the carbene fragments in the starting initiators. Initiators 1-2 lead to polyoctenamers mainly containing the cis units, whereas the use of complexes 3 and 4 affords polyoctenamers mainly containing the trans units. The structures of novel compound 2 and known complexes 1, 3, and 4 were determined by X ray diffraction analysis.
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