(C-AS)(2)-HYDROGEN DEFECTS IN GAAS - A FIRST-PRINCIPLES STUDY

Hydrogen-related local vibrational modes at 2643, 2651, 2688, 2725, 27 29, and 2775 cm(-1) are thought to arise from C-H stretch modes from d efects similar to the hydrogen-passivated carbon acceptor complex CAsH . These lines appear in samples that are grown using trimethylgallium metalorganic precursors, and it has been suggested that the 2688-, 272 5-, 2729-, and 2775-cm(-1) bands may be due to C-As dimers decorated w ith one or more H atoms. We present here the structures. energies, and vibrational modes of (C-As)(2), (C-As)(2)H, and (C-As)(2)H-2 complexe s obtained from ab initio local-density-functional cluster calculation s to investigate these assignments.