FORMATION OF SEGREGATED CELL STRUCTURE FOR MBE GROWTH OF MISMATCHED SEMICONDUCTORS

In this work the cellular structure is proposed as a buffer layer for defect-free heteroepitaxial growth of mismatched materials. The micro- cellular buffers were formed by 80 keV In+ ion implantation into singl e-crystalline (001) silicon wafers (2 X 10(16) cm(-2)) followed by Q-s witched laser annealing at an energy density of about 1.2-3.5 J/cm(2). The structure of the obtained surface was investigated by plan-view a nd cross-section transmission electron microscopy. It has been found t hat the In-implanted, and subsequently laser annealed, Si surface exhi bits a structure consisting of a system of 'seed' pads (cells) separat ed by indium filled trenches (walls of the cell). The linear dimension s of the pads and trenches are measured to be 15-100 and 3-5 nm, respe ctively, which is close to the optimal values for defect-free epitaxia l growth of mismatched materials. The obtained Si[In]/Si buffer layers were used for heteroepitaxial growth of GaAs films. The density of ex tended defects in GaAs grown on these buffers was found to be consider ably lower as compared to conventional GaAs/Si structures grown at sim ilar conditions. (C) 1997 Elsevier Science S.A.