High-quality epitaxial Bi(111) films on Si(111) by isochronal annealing

Bi(111) films grown on Si(111) at room temperature show a significantly higher roughness compared to Bi films grown on Si(100) utilizing a kinetic pathway based on a low-temperature process. Isochronal annealing steps of 3 min duration each with temperatures up to 200 °C cause a relaxation of the Bi films' lattice parameter toward the Bi bulk value and yield an atomically flat Bi surface. Driving force for the relaxation and surface reordering is the magic mismatch of 11 Bi atoms to 13 Si atoms that emerges at annealing temperatures above 150 °C and reduces the remaining strain to less than 0.2%.

► Heteroexpitaxial growth of single crystalline epitaxial Bi(111) films on Si(111). ► Post-growth isochronal annealing yields to high quality Bi(111) films. ► Strain state analysis shows relaxation of lattice parameter during annealing. ► ‘Magic mismatch’ determines strain state.