COLUMN-III VACANCY-INDUCED AND IMPURITY-INDUCED LAYER DISORDERING OF ALXGA1-XAS-GAAS HETEROSTRUCTURES WITH SIO2 OR SI3N4 DIFFUSION SOURCES

Experiments are described determining the critical parameters for vacancy- and impurity-induced layer disordering of AlxGa1-xAs-GaAs quantum-well heterostructure (QWH) crystals that utilize SiO2 and Si3N4 diffusion source layers. The SiO2- or Si3N4-capped QWH crystal surface reaches equilibrium with the external annealing ambient by diffusion of Ga and As through the encapsulant layer, thus determining the crystal-surface deviation from stoichiometry and the column III vacancy concentration for layer disordering. By proper design of the QWH crystal, encapsulant layer thickness, and annealing ambient, the SiO2 (Si3N4) can be employed as a column III vacancy source (or mask) or as a Si and O (or N) diffusion source to effect impurity-induced layer disordering.