The evolution of the surface morphology and reconstruction during growth by
molecular beam epitaxy of InAs on the GaAS(001)-(2 x 4) surface has been s
tudied using rapid-quench scanning tunnelling microscopy. At a growth tempe
rature of 500 degreesC and with an As :In flux ratio of 2:1 (growth rate 0.
068 ML s(-1)), the two-dimensional islands formed at sub-monolayer (ML) cov
erages exhibit an In-terminated locally (3 x 1) reconstruction, in contrast
to the (2 x 4) reconstruction of islands grown at higher flux ratios. The
island size distributions exhibit scaling behaviour for all flux ratios, wh
ich also matches the scaling form for GaAs homoepitaxy on the (2 x 4) surfa
ce. Deposition of more than 1 ML InAs results in the formation of a disorde
red and alloyed wetting layer whose characteristics are independent of the
flux ratio and which exhibits a (1 x 3) reconstruction. The role of heteroe
pitaxial strain in these changes is discussed. (C) 2001 Elsevier Science B.
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