Optical transitions of infinite and finite strained Si/Ge superlattices

A systematic study of the optical transitions of pseudomorphically strained (Si)n/(Ge)n superlattices grown on Si1−xGex(001) buffers is presented. The influence of period (n+m), synthesis (n/m), and strain on the transition energies and transition probabilities at the Γ point is studied. This is performed with the use of a realistic tight-binding model in the three-center representation. The transition energies and probabilities for the finite superlattices (Si)4/(Ge)4 inside Si and (Si)5/(Ge)5 superlattice inside Ge are also studied. It is proposed that the most promising material for optoelectronic applications is the strain-symmetrized (Si)4/(Ge)6 strained layer superlattice.