Particulates: An origin of GaAs oval defects grown by molecular beam epitaxy

Abstract

We present micrographic evidence that particulates which inadvertently adhere to the wafer surface during substrate preparation result in the formation of oval defects in GaAs layers grown by molecular beam epitaxy (MBE). With elimination of particulate contamination, we simultaneously reduce the total defect density in 1-μm-thick GaAs MBE layers from a few thousand to about 300 cm−2. Further evidence indicates that most of these remaining defects also originate from the surface particulates which adhere during the process of wafer transfer and layer growth.