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Epitaxial layers of monoclinic β‐Ga2O3 were successfully grown on (0001) sapphire and ($ \bar 1 $11)As GaAs substrates using metal‐organic vapor‐phase epitaxy (MOVPE). Triethylgallium (TEGa) and N2O were used as precursors for gallium and oxygen, respectively. Growth conditions could be determined, where β‐Ga2O3 grows epitaxially on c ‐plane sapphire and ($ \bar 1 $11)As GaAs substrates. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) measurements identify a epitaxial relationship with ($ \bar 2 $01) β‐Ga2O3 || (0001) sapphire and ($ \bar 2 $01) β‐Ga2O3 || ($ \bar 1 $11)As GaAs. The observed sixfold rotational in‐plane symmetry results from differently oriented rotational domains of monoclinic β‐Ga2O3 with twofold symmetry. Thin films deposited on substrates of other orientation show the formation of the low‐temperature modification α‐Ga2O3. Optical transmission spectra measured in the spectral range from 200 nm to 2000 nm show a well‐distinct absorption edge at about 5 eV for layers grown on c ‐ and a ‐plane sapphire. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Velocity distributions of mass-identified evaporation residues produced in the Si+ Ca reaction have been measured at bombarding energies of 309, 397, and 452 MeV using time-of-flight techniques. These distributions were used to identify evaporation residues and to separate the complete-fusion and incomplete-fusion components. Angular distributions and upper limits for the total evaporation-residue and complete-fusion evaporation-residue cross sections were extracted at all three bombarding energies. The complete-fusion evaporation-residue cross sections and the deduced critical angular momenta are compared with earlier measurements and the predictions of existing models. The ratios of the complete-fusion evaporation-residue cross section to the total evaporation-residue cross section, along with those measured for the Si+ ' C and Si+ Si systems at the same energies, support the entrancechannel mass-asymmetry dependence of the incomplete-fusion evaporation-residue process reported earlier.PACS number(s): 25.70.Jj

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