Effect of surface encapsulation and As4 overpressure on Si diffusion and impurity-induced layer disordering in GaAs, AlxGa1-xAs, and AlxGa1-xAs-GaAs quantum well heterostructures

Abstract

Data are presented demonstrating that the surface encapsulant and the As4 overpressure strongly affect Si diffusion in GaAs and AlxGa1-xAs, and thus are important parameters in impurity-induced layer disordering. Increasing As4 overpressure results in anincrease in diffusion depth in the case of GaAs, and adecrease in diffusion depth for AlxGa1-xAs. In addition, the band-edge exciton is observed in absorption on an AlxGa1-xAs-GaAs superlattice that is diffused with Si and is converted to bulk crystal AlyGa1-yAs via impurity-induced layer disordering. In contrast, the exciton is not observed in absorption on GaAs diffused with Si in spite of the high degree of compensation. These data indicate that the Si diffusion process, and the properties of the diffused material, are different for GaAs and for AlxGa1-xAs-GaAs superlattices converted into uniform AlyGa1-yAs (0 ≤y ≤x ≤ 1) via impurity-induced layer disordering with the amphoteric dopant Si.