Size control of self-assembled InP/GaInP quantum islands

Two types of coherently strained InP islands were found for the self-organized MOVPE growth of InP on Ga0.51In0.49P. This is in contrast to the well examined InAs/GaAs system. In this paper we give an explanation for this observation. We attribute the coexistence of two types to the fact that the larger islands (h = 20 nm) are energetically favorable whereas the smaller islands (h = 5 nm) represent the initial non-equilibrium state. Further increase of the size of the larger islands is suppressed by an energy barrier resulting from an activation energy for the onset of dislocation formation. The amount of smaller islands was increased for growth conditions with reduced surface diffusion, i.e. low growth temperatures or high growth rates. It is also shown that beside the growth parameters the orientation of the substrate played an important role in the control of the island size. For substrates with high misorientation combined with low growth temperatures we were able to suppress the formation of the larger islands. AFM- and PL-measurements were used to demonstrate this behavior. (C) 1998 Published by Elsevier Science B.V. All rights reserved.