UNIAXIAL LATTICE EXPANSION OF SELF-ION-IMPLANTED SI

Lattice strain in self-ion-implanted Si is investigated. Under certain irradiation conditions, a unique strain field is shown to form over the range of the ions. This strain field is one-dimensional and expands the lattice along the direction normal to the surface of the crystal. This phenomena is investigated over a wide range of ion energy (100 keV and 1.25 MeV) and at different implantation temperatures. The presence of uniaxial strain is shown to correlate with a particular damage morphology in Si. This ion-induced morphology and the irradiation conditions under which it forms are discussed, as well as the mechanism which leads to uniaxial, lattice strain. Both ion channeling and x-ray diffraction analyses are used to characterize the strain field.