Evidence of stress dependence in the diffusion of point defects in GaAs/GaAlAs heterostructures

We present experimental results on the selective interdiffusion of GaAs/GaAlAs quantum well heterostructures induced by SiO₂ and Si₃N₄ capping and annealing. Comparative studies show that interdiffusion occurs under SiO₂ in the case of patterned Si₃N₄ strips coated with SiO₂, while interdiffused areas surprisingly appear below Si ₃N₄ in the reversed case where patterned SiO₂ strips are coated with Si₃N₄. Our work demonstrates that the diffusion of the excess gallium vacancies, which are responsible for the enhanced interdiffusion, is driven by the stress field generated by the dielectric patterned layers