Mb. Johnson et al., ATOMIC-SCALE VIEW OF ALGAAS GAAS HETEROSTRUCTURES WITH CROSS-SECTIONAL SCANNING-TUNNELING-MICROSCOPY/, Applied physics letters, 63(9), 1993, pp. 1273-1275
Atomically resolved cross-sectional scanning tunneling microscope topo
graphic images of heterostructures that include a sequence of 1, 2, 5,
and 10 nm AlGaAs and GaAs layers are presented. These layers clearly
show alloy fluctuations and interface roughness on an atomic scale. In
the thick AlGaAs layers a mottled structure with regions of higher Al
content about 2 nm wide and elongated in [112BAR] or [112BAR] directi
ons are observed. Similarly, the interfaces are rough on a 2 nm length
scale. These results suggest that, for the conditions used for the ep
itaxial growth of the ternary layers, Al-rich regions nucleate and gro
w anisotropically.