The role of strain in hydrogenation induced cracking in Si∕Si1−xGex∕Si structures

Hydrogenation induced cracking in molecular beam epitaxy grown Si∕Si1−xGex∕Si heterostructures is studied. The Si1−xGex layer buried between an ∼200nm thick Si capping layer and the Si substrate is ∼5nm thick. After plasma hydrogenation, long range H migration and H trapping at the Si1−xGex layer are observed. With increasing Ge concentrations, the amount of H trapping increases, cracking along the Si1−xGex layer is smoother, and fewer defects are formed in the Si capping layer. The study suggests maximizing the interfacial strain to achieve the smoothest cracking with minimized radiation damage for ultrathin silicon-on-insulator technology.