Observation of lateral confinement effect in Ge quantum wires self-aligned at step edges on Si(100)

Spontaneous formation of step-edge Ge quantum wires and lateral quantum confinement effect are clearly observed in Si submonolayer-Ge/Si heterostructures grown on Si(100). By depositing submonolayer equivalent Ge (Q), the Ge atoms are found to line up in a wire-like fashion at the 〈01̄1〉 step edges as revealed by plan-view transmission electron microscopy. Photoluminescence (PL) peak energy shift with Q due to lateral quantum confinement of holes is clearly observed, and PL features characteristic of the quasi-one-dimensional system are also addressed.