Nanoindentation investigation of solid-solution strengthening in III-V semiconductor alloys

Abstract III-V semiconductor alloys have been grown onto lattice-matched substrates. These systems correspond to In x Ga 1 – x As with x ≈ 0.5 grown on InP, and to In y Ga 1 – y P with y ≈ 0.5 grown on GaAs and were used in order to produce epitaxial layers free of structural defects (threading dislocations). InGaP alloys, in contrast to InGaAs, are known to order partially to a degree η that can be controlled by the growth temperature and substrate orientation (here, η could be adjusted in the range 0 – 0.5). Nanoindentation tests were carried out to measure the mechanical response of the heteroepitaxial layers. Transmission electron microscopy was used to characterize the structure as well as the plastic zones generated into the specimen by nanoindentation. Comparison of the alloys with binary references (InAs, InP, GaAs, GaP bare substrates) showed strengthening, with the hardness and flow-stress values being much larger than those of binary softer reference materials (InP and InAs).