The isovalent indium delta-doping of LT-GaAs films, performed additionally to a uniform one with shallow donors (Si) and acceptors (Be), is shown by TEM to provide As cluster arrays ordered along the growth direction. At the appropriate growth and annealing conditions As/GaAs layered insulating-semiconducting structures have been obtained with GaAs spacers free of clusters between As cluster sheets as thick as 30 nm. In parallel, the indium diffusivity in LT-GaAs is estimated to be 5x10~(-18) cm~2/s in the temperature range from 500 to 600 deg C.
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