Improvement of GaAs crystal quality grown on Si by metalorganic chemical vapor deposition through twohyphen;dimensionalhyphen;like nucleation with aninsituH2/AsH3plasma cleaning at 450thinsp;deg;C

摘要

We demonstrate thatinsituSi cleaning techniques prior to low‐temperature GaAs buffer layer growth affect the morphology of the GaAs buffer layer in the early stages of growth and the crystal quality of 3‐&mgr;m‐thick GaAs grown epitaxially afterward on the buffer layer at 650 °C. Both thermal cleaning and hydrogen/arsine plasma cleaning at 650 °C result in a bimodal distribution of GaAs nuclei on Si, although the number of larger nuclei with {111} facets decreases with the plasma cleaning. No such larger islands are observed with hydrogen/arsine plasma cleaning at 450 °C, and this makes possible a two‐dimensional‐like nucleation of the buffer layer. This two‐dimensional‐like nucleation of the buffer layer, in contrast to the bimodal nucleation behavior observed in other cleaning conditions, leads to a significant improvement in GaAs crystal quality with a reduction of full width at half maximum from 755 to 306 arcsec as measured by double‐crystal diffractometry.