Stability of AlAs in AlxGa1-xAs-AlAs-GaAs quantum well heterostructures

Data are presented on the long‐term (≳8 yr) degradation of AlxGa1−xAs‐AlAs ‐GaAs quantum well heterostructure material because of the instability of underlying (internal) AlAs layers. Material containing thicker (>0.4 μm) AlAs ‘‘buried’’ layers (confining layers) is found to be much less stable than material containing thinner (≲200 A) AlAs layers. Hydrolysis of the AlAs layers because of cleaved edges and pinholes in the cap layers leads to the deterioration.