MATERIALS CHARACTERIZATION OF SI1-X-YGEXCY SI SUPERLATTICE STRUCTURES/

Pseudomorphic Si1-x-yGexCy/Si superlattice structures on Si were prepa red by molecular beam epitaxy in the compositional range: 8 < x < 44% and 0 < y < 4.4%, with layer thicknesses between 5 and 35 nm. Comprehe nsive materials characterization was carried out by Rutherford and C-r esonance backscattering combined with ion channeling. Complementary an alysis was provided by secondary ion mass spectrometry (SIMS) and high -resolution transmission electron microscopy. The Si1-x-yGexCy layer c omposition was derived by measuring the average Ge and C concentration s by ion backscattering and the layer thicknesses from electron microg raphs. Carbon depth profiles of good sensitivity were derived from SIM S profiling. The superlattice strain was measured by X-ray diffraction and usually found to be compressive. However, lattice-matched and ten sile superlattice films were obtained for alloys with similar to 10% G e. The tensile him bad growth defects - microtwins and stacking faults - which could be observed by TEM and detected by ion channeling. (C) 1997 Elsevier Science S.A.