Indium surface segregation in InGaAs-based structures prepared by molecular beam epitaxy and atomic layer molecular beam epitaxy

We present a comparative study on In surface segregation in InGaAs/GaAs structures prepared by molecular beam epitaxy (MBE) and atomic layer MBE (ALMBE) at different growth temperatures. The effect of segregation is evaluated by the energy position of exciton transitions in pseudomorphic 10 ML thick In_xGa_1−xAs/GaAs (0.15≤x≤0.30) and in 1 ML thick InAs/GaAs quantum wells. We show that: (i) In segregation decreases with the growth temperatures and is minimized at ALMBE and MBE growth temperatures lower than 260 and 340°C, respectively, and (ii) the segregation is more effective in ALMBE structures than in the MBE counterparts. The growth conditions that have been singled out allow the preparation of structures with high photoluminescence efficiencies even at the low growth temperatures required to minimize In segregation.