Control of silica cap properties by oxygen plasma treatment for single-capselective impurity free vacancy disordering

By exposing the SiO2 films used as annealing caps in the process of impurit y free vacancy disordering (IFVD) to an oxygen plasma, which is produced in a reactive ion etching machine, the effect of the exposed caps on quantum well intermixing can be substantially controlled. The effect of the oxygen treatment is manifested in inhibiting the Ga outdiffusion from GaAs/AlGaAs heterostructures. A selective IFVD process using identical silica caps has been obtained by selective exposure of the caps to oxygen plasma. Different ial band gap shifts in excess of 100 meV were achieved with control samples exhibiting band gap shifts less than 10 meV. (C) 1999 American Institute o f Physics. [S0003-6951(99)02805-3].