Elimination of ‘‘pair’’ defects from GaAs layers grown by molecular beam epitaxy

Abstract
In addition to ‘‘oval’’ defects, ‘‘pair’’ defects are observed on molecular beam epitaxially grown GaAs wafers. In this letter it is demonstrated that these defects originate from sulfur on the substrate surface caused by a 4:1:1 (H2SO4:H2O2:H2O) etch. The defects can be completely eliminated by dipping the substrate in 30% HCl solution for 5 min following a sulfuric acid etch.