Optical and photoelectrical properties of GeSi nanoislands

Raman and lateral photoconductivity spectra of self-assembled SiGe nanoislands with heights of ∼1 to 2 nm and bases of 10–20 nm were studied. Investigated heterostructures formed at a temperature 300 °C after deposition of Ge with a nominal layer thickness of d Ge ⩽ 8 monolayers have the shape of the so-called hut clusters. It was estimated that the value of elastic deformation (ε xx ) is −0.028 ± 0.002 (ε zz = 0.015 ± 0.002), the germanium content in islands ( x ) is 0.87 ± 0.05. It was determined that the value of the valence band energy offset in the heterojunction between the strained Si 0.13 Ge 0.87 layer of nanoislands and adjacent stretched Si is ∼0.47 eV.