The physical origin of InAs quantum dots on GaAs(001)

We propose that large heteroepitaxial stress causes InAs to melt when deposited on GaAs(001) at approximately 770 K. This leads to mixing with the substrate in order to realize a local minimum in the Gibbs free energy of the liquid phase, producing an approximate liquid composition of In0.8Ga0.2As.The liquid phase facilitates mass transport, leading to quantum dot formation. Dot formation occurs after 2.0 monolayers of liquid material accumulate in order to minimize the surface tension but without reducing the net coordination of the liquid phase atoms. Ge quantum dots on Si(001) are also discussed, and the influence of viscosity effects is inferred.