Modified strain and elastic energy behavior of Ge islands formed on high-miscut Si(0 0 1) substrates

Abstract

We investigate here the influence of Si substrate miscut on the strain and elastic energy of Ge islands. We show how the morphology, composition and the elastic energy for 4 and 13 monolayers (ML) Ge islands grown at 600 °C and 730 °C on vicinal Si(0 0 1) surfaces change with miscut angles ranging between 0° and 10°. Scanning Tunneling Microscopy is used to determine the island morphology. Resonant x-ray diffraction near the Ge-K absorption edge allows the determination of the Ge concentration as well as the elastic energy stored on such structures from their dependency on the lattice parameter. Simulations using the Finite Elements Method indicate that the enlargement of the SiGe broad peak retrieved from the x-ray diffraction measurements is actually caused by the asymmetrical faceting induced by large miscut angles. Such faceting has a strong effect on island density and elastic energy, producing differences that are proportional to those observed in conditions with distinct SiGe content.