Analysis of twin defects in GaAs(111)B molecular beam epitaxy growth

The formation of twin is common during GaAs(111) and GaN(0001) molecular be am epitaxy (MBE) metalorganic chemical vapor deposition growth. A stacking fault in the zinc-blende (ZB)(111) direction can be described as an inserti on of one monolayer of wurtzite structure, sandwiched between two ZB struct ures that have been rotated 60 degrees along the growth direction. GaAs(111 )A/B MBE growth within typical growth temperature regimes is complicated by the formation of pyramidal structures and 60 degrees rotated twins, which are caused by faceting and stacking fault formation. Although previous stud ies have revealed much about the structure of these twins, a well-establish ed simple nondestructive characterization method which allows the measureme nt of total aerial density of the twins does not exist at present. In this article, the twin density of AlCaAs layers grown on 1 degrees miscut GaAs(1 11)B substrates has been measured using high resolution x-ray diffraction, and characterized with a combination of Nomarski microscopy, atomic force m icroscopy, and transmission electron microscopy. These comparisons permit t he relationship between the aerial twin density and the growth condition to be determined quantitatively. (C) 2000 American Vacuum Society.