Detailed transmission electron microscopy (TEM) and transmission electron d
iffraction (TED) examination has been made of metalorganic molecular beam e
pitaxial GaAsN layers grown on (001) GaAs substrates. TEM results show that
lateral composition modulation occurs in the GaAs1-xNx layer (x < 6.75%).
It is shown that increasing N composition and Se (dopant) concentration lea
ds to poor crystallinity. It is also shown that the addition of Se increase
s N composition. Atomic force microscopy (AFM) results show that the surfac
es of the samples experience a morphological change from faceting to island
ing, as the N composition and Se concentration increase. Based on the TEM a
nd AFM results, a simple model is given to explain the formation of the lat
eral composition modulation.