For InAs Stranski–Krastanov (SK) island growth on GaAs by molecular‐beam epitaxy, we show that the in‐plane island diameter varies exponentially with the growth temperature over the range of 390–540 °C. A transition region in SK growth between isolated island growth and island coalescing is investigated as functions of growth temperature and equivalent InAs layer‐by‐layer monolayer (ML) coverage in order to extend the isolated island regime for quantum confinement applications. InAs islands of 150 A˚ in diameter have been grown. Growth of In0.5Ga0.5As islands indicates an increased 2D epitaxial region before island nucleation and a decreased island concentration compared to growth of InAs islands. ©1995 American Institute of Physics.