Raman determination of uniformity of multilayer Si/Ge structures with Ge quantumdots

Abstract

Spectra of Raman scattering by optical phonons of multilayer Si/Ge structureswith Ge quantum dots (QDs) grown by means of low-temperature (Ts = 250 °C) molecular beam epitaxy are studied. Two types of Ge islands are observed:pseudomorphic to a Si matrix, and those in which the strains are relaxed non-uniformly.Application of polarization measurements allows us to separate the phonon linescorresponding to these two components of a QD array. A method for the quantitativeestimation of the degree of uniformity of the QD array, determining the integratedelectron–hole spectrum of the structure, is proposed.