Optical phonon spectrum of germanium quantum dots

We have observed additional lines, shifted in both directions relative to t he frequency of the bulk phonon of Ge, in the Raman scattering spectra from optical phonons in germanium quantum dots. The observed phonon modes are s hown to be due to the straining of the quantum dots as a result of the latt ice mismatch of the Ge and Si matrices. The observed frequency shifts, with allowance for optical-phonon localization effects, make it possible to det ermine the sizes of the regions with different strain states in the quantum dots. (C) 1999 American Institute of Physics. [S0021-3640(99)01016-6].