SIMS study of Al thermal diffusion in MBE-grown sandwiched-ZnSTe structures

Sandwiched structures that consist of ZnSTe/ZnSTe: Al/ZnSTe were fabricated by the molecular beam epitaxy technique on three GaAs substrates oriented along (1 0 0), (5 1 1) and (7 1 1), respectively, to study the thermal diffusion of Al dopant in ZnS 0.986 Te 0.014 matrix by secondary ion mass spectroscopy depth profiling. The relative sensitivity factor of Al with respect to Zn was determined to be 4.5 ± 0.5 x 10 19 cm -3 . The Al diffusion coefficients at annealing temperature of 450 and 550°C were found to be 2.1 x 10 -15 cm 2 /s and 2.1 x × 10 -14 cm 2 /s, respectively, and the diffusion seems to be isotropic, regardless of the crystallographic orientation.