Impurity-free interdiffusion in GaAs/Al0.54Ga0.46 As multiple quantum wells capped with PECVD SiOx: effect of nitrous oxide flow

Impurity-free vacancy interdiffusion of GaAs/Al_0.54Ga _0.46As quantum wells (QWs) was achieved using SiO_x capping followed by rapid thermal annealing at 950°C. The SiO_x films were plasma deposited using N₂O/SiH₄ flow at 300°C and 20 W rf power. The stoichiometry of capping layers were altered by varying the flowrate of N₂O. In the samples studied, the above process allows continuously variable energy shifts as high as ~15O meV while still maintaining clearly resolved excitonic behavior. The degree of intermixing is not controlled by x only but, also, by the density of the SiO_x layers, Our results, therefore, suggest that, in addition to the solid solubility of Ga in SiO_x, intermixing in SiO_x capped MQW heterostructures depends on the mobility of Ga atoms in the oxide caps