Effect of MOVPE growth interruptions on the gallium arsenide interior interface morphology

We have studied MOVPE-grown interior GaAs/AlAs interfaces using highly sele ctive etching combined with atomic force microscopy. We observe substantial restructuring for samples grown on both (100) exact and vicinal substrates . Interface structures differ significantly fi om sample surfaces after coo l-down. On (100) exact substrates, the macroscopic monolayer island and ter race structure smoothes during growth interruptions over the whole 2 min pe riod of time studied. A new, mesoscopic scale of roughness is detected for the first time. This structure does not depend on growth interruption time but does change its typical size at different growth temperatures. On vicin al substrates, we observe and quantify step bunching during growth interrup tion. The sowing surface itself is smooth, in sharp contrast to the corresp onding macrostepped GaAs sample surface obtained after cooling down.