The interface of direct bonded GaAs to GaAs has been studied by scanning tr
ansmission electron microscopy and electron energy loss spectroscopy. Voids
are seen along the boundary with most being partially filled with a galliu
m particle. Two general sizes of voids are seen. The large voids (d similar
to 45 nm) are distributed in an approximately linear relationship and the
smaller (d similar to 12 nm) randomly. In compliant substrates, one of the
layers is made thin (less than or equal to 10 nm) and twisted similar to 45
degrees. The larger voids often extend past this thin compliant layer, but
no evidence of granularity of the epitaxial film is observed. (C) 2000 Ame
rican Institute of Physics. [S0003-6951(00)00119-4].