Defect reduction of GaAs/Si epitaxy by aspect ratio trapping

Abstract

We report on the metallorganic chemical vapor deposition growth of GaAs on patterned Si (001) substrates, which utilizes the aspect ratio trapping method. It was found that when growing GaAs above the ${\text{SiO}}_2$ trenched region, coalescence-induced threading dislocations and stacking faults originated on top of the $\text{GaAs}/{\text{SiO}}_2$ interfaces. These defects were found to be indirectly related to the initial defect-trapping process during trenched GaAs growth. Causes of coalescence defect formation and its reduction were experimentally investigated by employing a two-step growth optimization scheme. Improvement of material quality has been characterized by cross-sectional and plan-view transmission electron microscopy and x-ray diffraction.