Epitaxial growth of EuS on InAs(100) and InP(100)

We studied the growth of thin europium sulfide films on InAs and InP substrates. The EuS layer thickness varied from 2 to 20 nm. The substrates were chosen due to a close matching with the EuS lattice constant and because of the zinc-blende structure compatible with GaAs technology. Deposited films were characterized by means of low-energy electron diffraction (LEED) and atomic force microscopy (AFM). The measurements provide evidence for epitaxial growth of EuS. A high crystalline order is present in the EuS layer. Islands are formed on both substrates. They are larger on InAs than on InP for the same EuS film thickness. The size of the islands decreases for both substrates from several hundred to around 50 nm beyond thicknesses of 4 and 20 nm on InP and InAs, respectively. AFM measurements corroborate these findings revealing more details about the morphology of the EuS layers. The islands are denser on InP completely covering the underlying substrate. On InAs, the islands are more widely spaced, forming broad terraces. Analysis of the terrace edges revealed a minimum step height in accordance with a monolayer of EuS along the 〈100〉 direction.