OPTICAL STUDIES OF GE ISLANDING ON SI(111)

We report an experimental study of the optical properties of island la yers resulting from molecular beam epitaxial deposition of Ge on Si(11 1) substrates. The combination of electroreflectance spectroscopy of t he E(1) transition and Raman scattering allows us to separately determ ine the strain and composition of the islands. For deposition at 500 d egrees C a deposited layer of 1.36 nm of Ge assembles into 80 nm diame ter islands 11 nm thick. The average Si impurity content in the island s is 2.5% while the average in-plane strain is 0.5%. Both strain and S i impurity content in islands decrease with increasing Ge deposition. (C) 1997 American Institute of Physics.