Size control of self-assembled InP/GaInP quantum islands

Two types of coherently strained InP islands were found for the self-organi zed MOVPE growth of InP on Ga0.51In0.49P. This is in contrast to the well e xamined InAs/GaAs system. In this paper we give an explanation for this obs ervation. We attribute the coexistence of two types to the fact that the la rger islands (h = 20 nm) are energetically favorable whereas the smaller is lands (h = 5 nm) represent the initial non-equilibrium state. Further incre ase of the size of the larger islands is suppressed by an energy barrier re sulting from an activation energy for the onset of dislocation formation. T he amount of smaller islands was increased for growth conditions with reduc ed surface diffusion, i.e. low growth temperatures or high growth rates. It is also shown that beside the growth parameters the orientation of the sub strate played an important role in the control of the island size. For subs trates with high misorientation combined with low growth temperatures we we re able to suppress the formation of the larger islands. AFM- and PL-measur ements were used to demonstrate this behavior. (C) 1998 Published by Elsevi er Science B.V. All rights reserved.